Copyright: Copyright © Ligos Corporation 2000.


Table of Contents
LSX-MPEG Encoder

Help Table of Contents

LSX-MPEG Encoder

Introducing LSX-MPEG Encoder

What is the LSX-MPEG Encoder?

What’s New in LSX-MPEG Encoder?

Quick Start Tutorial

Using LSX-MPEG Encoder

Main Menu

Toolbar

Main Program Window

Profile Manager

Advanced Parameters

Encoding

Batch Processing

Achieving Best Results:

Optimizing Topics

Beginner’s Guide to MPEG Encoding

Achieving Fastest Encoding

Achieving Best Picture Quality

Balancing Quality and Performance

Encoding with Low Bitrates

Frequently Asked Questions

FAQ Topics

Understanding MPEG

What is MPEG?

MPEG Constrained Parameters, Profiles & Levels

Appendix

LSX-MPEG Player

MPEG Resources

Glossary


Introduction - What is LSX-MPEG Encoder?
Introducing LSX-MPEG Encoder

LSX-MPEG Encoder

What is LSX-MPEG Encoder?

LSX-MPEG Encoder is an application for transcoding AVI files into MPEG files. Specifically, the LSX-MPEG Encoder can create multiplexed MPEG-1 and MPEG-2 video and audio streams.

The LSX-MPEG Encoder is optimized to achieve very fast encoding for most standard frame sizes and frame rates of video required in multimedia applications.

Advantages:

LSX-MPEG Encoder utilizes Intel MMXTM technology for maximum MPEG encoding speeds. The LSX-MPEG Encoder automatically detects if it is running on MMX compatible processors and will utilize those instructions for faster encoding, if available.

LSX-MPEG Encoder utilizes our revolutionary motion estimation algorithm for fastest MPEG encoding available in software. Due to our LightSpeed algorithm, the LSX-MPEG Encoder works several times faster than other software encoding solutions, while providing virtually the best possible compression and quality. Our super fast algorithm of motion estimation is available for licensing for software and hardware implementations of image compression and recognition.

The LSX-MPEG Encoder is flexible. Our simple and intuitive interface is easy for new users, but still allows video professionals to control a number of MPEG encoding parameters. A special mode for creating very low data rate MPEG video files makes the program great for creating low-bandwidth MPEG files for the Internet. New features such as Variable Bitrate control allow the user to produce better MPEG files than ever before.

If you are new to MPEG encoding and the LSX-MPEG Encoder, you can get started immediately with our newest Quick Start Tutorial. Using an AVI clip available from our website at  http://www.ligos.com/products/sample_clips.shtm , you’ll be able to quickly familiarize yourself with the powerful but simple interface of the LSX-MPEG Encoder, and immediately see the advantages MPEG has over AVI codecs for producing smaller, better looking video.

Contacting Us:

Ligos Technology

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Suite 450

San Francisco, CA  94108

Ligos Corporation Home Page:  http://www.ligos.com/

Technical Support:

Technical support is provided to registered users only. At Ligos, we try to provide the fastest and most accurate technical support possible. Please submit bugs, problems and suggestions with our Tech Support Form on our website at http://www.ligos.com/support/report.shtm .

Comments and suggestions:

E-mail -	info@ligos.com

Sales inquiries:

E-mail -	sales@ligos.com

Phone -	1-888-464-8765

Fax -	(415) 437-6139


What's new in LSX-MPEG Encoder?
Introducing LSX-MPEG Encoder

LSX-MPEG Encoder

What’s new in LSX-MPEG Encoder?

1)	Single pass Variable Bitrate control with three modes of control and operation

2)	Support for 48 kHz audio input and output

3)	Custom controls for adding MPEG Sequence Headers

4)	Ability to specify “Closed GOPs” for increased compatibility with MPEG editing applications

5)	Full implementation of Video Buffer Verifier (VBV), including protection from overflow and underflow errors

6)	New "Edges" filter allows users to cover up edge garbage and noise that often accompanies source files captured from VHS

7)	18 new and revised encoding Profiles that are more flexible and easier to use. Encode anything from exceptionally low variable bitrate MPEG video for the Internet, to MPEG for VideoCD, to full-blown MP@ML MPEG-2, all with just a few clicks

8)	Improved deinterlace function that creates higher quality progressive video from originally interlaced source

9)	LSX-MPEG Encoder now includes the LSX-MPEG Player, a software filter that provides quality playback of MPEG-2 video directly through Microsoft's Windows Media Player

10)	Improved, more efficient interface

11)	New Quick Start Tutorial

Supported MPEG Output Formats:

MPEG-2 program streams (ISO/IEC 13818-1)

MPEG-2 video elementary streams (ISO/IEC 13818-2)

MPEG-1 system streams (ISO/IEC 11172-1), including White Book VideoCD

MPEG-1 video elementary streams (ISO/IEC 11172-2)

MPEG-1 audio layer II elementary streams (ISO/IEC 11172-3)

Specifications for MPEG-1 Encoding Support:

1)	Supports user-defined frame sizes per the "constrained parameter bit stream" section of the MPEG-1 specification:

a)	Horizontal frame sizes less than or equal 768 pixels

b)	Vertical frame sizes less than or equal 576 pixels

c)	Picture area less than or equal 396 macroblocks/picture

d)	Supports user-defined frame rates less than or equal 30 frames/sec

e)	Supports user-defined data rates less than or equal 1812 Kbits/sec

f)	Motion vectors less than or equal 64

2)	Supports creation of audio only streams. (via *.mp2 temporary files)

3)	Supports encoding of MPEG-1 files at either constant bitrate or variable bitrate

4)	Supports creation of multiplexed MPEG-1 streams with audio stream (Layer 2 only) compression. The bit rate range follows ISO/IEC 11172-3 standard. It also supports mono, stereo, dual channel, and joint stereo mode

5)	Supports creation of “White Book” compliant MPEG-1 streams for VideoCD

Specifications for MPEG-2 Encoding Support:

1)	Support for the following MPEG-2 Profiles and Levels

a)	Main Profile and Low Level

b)	Main Profile and Main Level

c)	High Profile and High-1440 Level

d)	High Profile and High Level

2)	Supports user-defined aspect ratios of 1:1, 4:3, 16:9, 2.21:1

3)	Supports encoding of MPEG-2 files at either constant bitrate or variable bitrate

4)	Supports creation of multiplexed MPEG-2 streams with audio streams (MPEG-1 Layer II) compression. The bit rate range follows ISO/IEC 11172-3 standard. It also supports mono, stereo, dual channel, and joint stereo mode

Specifications for MPEG-2 Decoding (LSX-MPEG Player):

-	Works directly with the Windows Media Player as a Direct Show filter, giving you a fully powered media player (DirectShow and ActiveMovie compatible)

-	Support for real time decoding of MPEG-2 Program Streams (up to Main Profile@Main Level and 10 Mbps)

-	Support for full screen playback of up to Full D-1 resolution files, NTSC (720x480, 30fps) or PAL (720x576, 25 fps) on a Pentium II 450 MHz system with a DirectX compatible video card supporting YUV overlay mode, and Half D-1 on a 300 MHz Pentium II

-	Optimized for most efficient use of processor

-	Support for re-routing MPEG-1 System Stream video decode through our filter


Quick Start Tutorial

LSX-MPEG Encoder

To get started immediately with the LSX-MPEG Encoder, we’ve provided this Quick Start Tutorial. Detailed information is provided throughout this Help file for additional features such as Variable Bitrate control, skipping frames for lower bitrate encoding, and Batch Processing.

In order to reduce the download size of the LSX-MPEG Encoder, no media clips are provided with the application. If you plan on using these tutorials (highly recommended if you’re new to MPEG encoding), you’ll want to download the referenced AVI files from our website at:

http://www.ligos.com/products/sample_clips.shtm

From the website, get one AVI file each for The Balloon and The Dolphin. They are available in a number of different codec options, so download the one that will work best with your system.  If you have your own AVI clips, you can use those and save yourself the download, but try to use clips that match the specifications provided below. The tutorials will reference these clips specifically and your results could vary significantly if you’re using clips that differ in content, file size, and frame size.

The Balloon is a YUV compressed AVI, 3 seconds, 352x240, 2960 KB/Sec video, 44.1 kHz 16 bit stereo audio, balloon_yuv.avi when it’s unzipped. It will be used for the tutorial below.

The Dolphin is YUV compressed AVI, 5 seconds, 352x240, 2953 KB/Sec video, 44.1 kHz 16 bit stereo audio, dolphin_yuv.avi when it’s unzipped. It will be used in later tutorials, so you can download it later if you prefer.

Create a subdirectory called “Media” in your “C:\Program Files\LSX-MPEG Encoder 3.0\” directory, and save the files there. Now you can get started with MPEG encoding!

Encoding with the Profile Manager

When using the LSX-MPEG Encoder, the parameters used to encode an MPEG file are kept in a Profile. You can use the default Profile, use a predefined Profile selected from the Profile Manager, or you can create your own custom Profile. In this Tutorial we’ll show you how to quickly encode a file using the Profile Manager, and then take you through the steps of creating a custom Profile.

Start LSX-MPEG Encoder by choosing the program from the Start menu or clicking on the icon for the application in the program group.

The Encoder will automatically load a set of default parameters that are displayed in the Main Window, such as Frame Rate, Video Stream data rate, Frame Size, etc.. This is the information that will control the encoding process and determine the characteristics of the output file we’ll generate. Together, this information is known as a Profile. The top portion of the interface will remain blank until we actually start encoding some video.

Balloon_yuv.avi is a 3 second, 8.67 MB AVI file, and we want to encode it to MPEG to reduce the file size, but retain the quality. The easiest way to do this when first starting out with the LSX-MPEG Encoder is to use the Profile Manager. The Profile Manager includes predefined recommended Profiles, and allows you to create and store Profiles for later use. Open it from either the pulldown File menu item, or the Open Profile Manager button [image] on the toolbar.

When the Profile Manager is opened, you’ll see a two-part interface. The left side is a list box that displays predefined and custom MPEG-1 and MPEG-2 Profiles with descriptive names. When a Profile is selected, the right side displays the characteristics that make up that Profile (Format, Frame Rate, Data Rate, etc.). Either you can select a Profile based on the recommendation, or based on the goal you are trying to achieve. For instance, if you want something that is a good choice for a SIF resolution (352x240) AVI source file, you should get good results using the Profile “MPEG-1 (Recommended for SIF, 352x240 NTSC)”. If, however, you have a specific goal of taking a large AVI file and making it small enough for quick download over the Internet, you’d probably want to select “MPEG-1 (low bitrate, 10 fps simulated)” due to its optimized low data and frame rates. The choice is yours, and you can always choose one that’s close and customize it later.

We have a goal for Balloon_yuv.avi (reduce file size, keep the quality), so it is best to choose the recommended Profile. Select “MPEG-1 (recommended for SIF, 352x240 NTSC)” , and click Load Profile.

Now we need to select our Input File to convert and encode to MPEG. Near the Input File box, click on the Browse button. A standard Windows file dialog is displayed, prompting you to choose an AVI file for encoding. Select the file “Balloon_yuv.avi” from the “Media” sub-directory, and click the Open button.

An Information popup appears with an analysis of the Balloon_yuv.avi file. Click OK to continue. In addition to the Input File box being filled in, the Output File is now automatically named "Balloon_yuv.mpg", saved in the same folder. This can be changed, but we’ll leave it like this for now.

Let’s Preview the file… click on the Preview button [image] to the left of the Input File box. A window appears and plays back the clip. Close the movie window.

That’s all there is to it! As you can see, the parameters in the Main Window have been adjusted to match the Input File and the Profile we chose. If we don’t have any other changes to make, we can encode the file. Click on the Start MPEG Encoding button on the toolbar [image]. The application will display and begin encoding the video portion of the stream. A new section of the interface, MPEG Video Encoding in Progress, will appear. A meter will display a frame by frame accounting as each is encoded, and show information on image quality, current frame quality and elapsed encoding time. The application will then show a meter for the encoding progress of audio, followed by a meter for the multiplexing of audio and video. When finished, the Multiplexing Completed box is displayed, presenting a summary of information regarding the process. Close the dialog.

Let’s Play the finished file… click on the Play [image] button to the left of the Output File box. A media player should open to play the clip. Click play. As you can see, it is the same quality as the AVI file we input. A quick check on the file size (using Windows Explorer) shows that the resulting file is only about 500 kilobytes, 6% the size of the original! Close the movie window.

Next, we’ll look at some advanced options, and creating a custom profile.


Quick Start Tutorial, Part 2
Creating a Custom Profile

LSX-MPEG Encoder

Suppose that we felt 500 KB was still a bit large for Internet distribution and a 28.8 modem user. By sacrificing some quality, we can create a much smaller file that will download in less than a minute by customizing the data for our current Profile.

For this particular clip audio isn’t important, and audio can consume quite a bit of data. We can turn off audio by unchecking the Encode Audio box.

Next, we can customize the video data rate by specifying a lower value. Change the MPEG Video data rate from 1198 Kbits/sec (kilobits per second) to 400 Kbits/sec.

We can also customize our current Profile by modifying information contained in the Advanced Parameters pages. Click on the Advanced button on the Main Window.   The Advanced Parameters dialog appears with 12 tabbed areas, giving you detailed control over the application and the encoding process. If this looks overwhelming, don’t worry. We’ll go into detail on a few sections here, and each section elsewhere in this documentation.

First, a little technical background. At its simplest, MPEG files achieve their superior compression by encoding only the changes from one image (frame) to the next, eliminating the encoding of redundant information. In a typical video clip, there are 25 – 30 frames per second (fps). An MPEG file is made up of three types of frames: Intra (I frames), Predicted (P frames), and Bi-directional (B frames).

Consider a clip of a person from the shoulders up, looking forward and speaking into the camera (commonly referred to as a “talking head” clip). The I frame is a frame (generally the first in a sequence) that contains all the information about the current image. In this case, it would contain information about the face, the hair, the shoulders, the background – every detail of the picture.

The next frames probably look much like the first, with only a slight change in the picture (for instance, lips moving, eyes blinking). There’s no need to re-encode information about the background because it hasn’t changed. P frames are used for this type of information, to express only the change from previous frames to the present.

After looking forward and backward at a few I and P frames, the MPEG encoder can create an even smaller frame type in-between. These B frames are an expression of the changes from both the previous frames as well as the frames ahead.

This IPB frame structure and the elimination of redundant information is what makes MPEG superior to other forms of video compression. You can see the current sequence of I, P and B frames by clicking on the Sequence Parameters tab.

LSX-MPEG Encoder has a special feature to “skip” encoding the B frames, thus reducing the apparent frame rate and reducing file size. Go to the Special Parameters tab. This tab gives you options on skipping B frames to reduce frame rate. By clicking on Skip All B frames, we can eliminate B frames and reduce the file size without degrading image quality a great deal.

Finally, you can set the performance speed of the application to achieve faster encoding. This will affect quality, but usually not much. If getting your encoding done as quickly as possible is a priority, you can reset the speed in the Performance Parameter tab. Click on Performance and change Program performance from Normal speed to Fast.

Click OK to return to the Main Window.

We may want to use these settings in the future, so save them as a Custom Profile of your own. Go to the File menu, and choose Save profile As… When prompted for a descriptive name, type in something like “MPEG-1 for 28.8 Internet”, and click on Save. Now you’ll have these settings available to you in the Profile Manager.

Congratulations! At this point you have modified some advanced characteristics for the encoding of an MPEG file. Click on the Start MPEG Encoding button on the toolbar. The application will encode the video portion of the stream, and “MPEG Video Encoding in Progress” will appear. When finished, the Video Encoding Completed box is displayed. Note that encoding time was reduced by about 30 - 40% this time. Close the dialog.

Now we’ll Play the output file. Your media player will open to playback the MPEG file. Click play. As predicted, it’s a little blockier and the motion is not as smooth as 30 fps, but the video is still easily recognizable. A check on the file size (using Windows Explorer) shows that the resulting file is now 150 kb, less than 2% the size of the original! It would take about 40 seconds to download that from the Internet at 28.8kbps, so we’ve achieved our goal.

Now you’re beginning to see how impressive MPEG compression can be, and how easy and flexible the LSX-MPEG Encoder is for making these files. As you continue through this documentation, you’ll find many other ways to customize your encoding for different situations. You’ll also see how features such as Batch Conversion can make you more productive, and find plenty of information regarding MPEG itself.


Main Menu
Main Menus

LSX-MPEG Encoder

There are several pull-down menus in the LSX-MPEG Encoder main window. They are related to managing encoding Profiles, controlling the MPEG encoding process, and setting viewing parameters.

File Menu	When selected, the File pull-down menu displays the following options:

Reset Profile (Ctrl+R)	Reset all Profile parameters to default values.

Profile Manager (Ctrl+P)	Opens the Profile Manager dialog allowing the user to load an existing Profile (see Profile Manager section)

Import profile file… (Ctrl+O)	Allows the user to directly load the text *.prf file for a Profile into the main window (this is for those users of previous versions of LSX-MPEG Encoder who have legacy profiles not yet added to the Profile Manager).

Save Profile (Ctrl+S)	Saves the active encoding parameters for the current Profile

Save Profile As…	Same as Save option, but it will prompt the user with the Save Profile dialog box to let them specify a different Profile description.

Batch Processing (Ctrl+B)	Opens the Batch Processing dialog allowing the user to specify and encode a long series of input files automatically (see Batch Processing section)

Recent Files (select #)	This list represents the 5 most recently used profile files. Select any of these file names to open that profile file.

Exit	Exits the application. If the program is in the process of encoding an MPEG file this option will stop the encoding, but will not exit the program. When encoding is completed or stopped, you can safely exit the program.

Action Menu	When selected the Action pull-down menu displays the following options:

START Encoding (Alt+R)	Starts encoding an MPEG file. This option is activated only when an input file is selected or an existing profile file is loaded.

STOP Encoding (Alt+S)	Stops encoding an MPEG file.

PAUSE Encoding (Alt+P)	Suspends the MPEG encoding process. To continue encoding, press this option one more time or press the Pause button on the toolbar.

Preview input file	Opens a media player that plays the AVI file currently specified as the Input File.

Play output file	Opens a media player that plays the MPEG file currently encoded as the Output File.

View Menu	Displays options that determine how the program will display input and output during encoding. These options do not affect the output file, only the display of the interface, and display during encoding. They may affect the speed of encoding, as noted.

Show Input Stream Frames (Alt+I)	This option enables the MPEG Encoder to show input frames during encoding, OFF by default. You will find that leaving this disabled can increase the speed of encoding.

Show Output Stream Frames (Alt+O)	This option enables the MPEG Encoder to show output frames during encoding, ON by default. You will find that disabling this can often give you an increase in the speed of encoding.

Scale Images To Window (Alt+W)	This option enables the program to rescale input and/or output frames to fit entirely into a window (otherwise the program may crop the image), ON by default. Rescaling the image does significantly slow the encoding process.

View Toolbar (Alt+T)	This toggle selection will turn on or off the toolbar, ON by default.

Show AVI File Information	Displays a box with the currently selected AVI file’s information.

Save current settings as Default	When selected, this will save current parameters (including settings in the Main window) upon exit.

Suppress warning messages	Turns off pop-up warning messages during the encoding process.

Help Menu	Displays the following information options:

Help Topics (F1)	Activates on-line help.

About LSX-MPEG Encoder…	Displays the About dialog box and version info


Toolbar
Toolbars

LSX-MPEG Encoder

The program toolbar contains buttons for several application functions. Some buttons may appear grayed out if they are not available in the current program mode of operation. Holding the cursor over the buttons will result in a pop-up description of the function.

Below is a description of each button, listed left to right.

Reset Profile	Press this button to clear the current stream encoding Profile settings and reset to the default parameters.

Open Profile Manager	Press this button to bring up the Profile Manager dialog in which you can view and load MPEG stream encoding profiles.

Save current Profile	Press this button to save all current settings under the Profile name currently loaded.

View AVI Information	Displays a box with the currently selected AVI file’s information.

Batch Processing 	Press this button to bring up the dialog for Batch Processing, in which you can set up a list of files in a queue to be encoded.

Start MPEG Encoding	Press this button to start the encoding process. This button is not enabled (grayed out) when the program is started. It will be activated either when the user selects an input and output file name, or when the user loads an existing Profile.

Stop MPEG Encoding	This button stops the encoding process.

Pause MPEG Encoding	This button pauses the encoding process. To resume the encoding process, press this button again.

Help Topics	This button will activate on-line help.


Main Program Window

LSX-MPEG Encoder

The Main Program Window allows the user to specify input and output file names and some other general parameters necessary for encoding. The main window displays: input file name, output file name, frame width and height, amount of frames to encode, number of the first frame to encode, output file format (VideoCD, MPEG-1, MPEG-2), frame rate, and data rate in kilobits per second. When the application first opens, the Output Video Stream display will show the LSX-MPEG logo. Once you start encoding, this image will be replaced by the video you are encoding.

The first step in encoding a new file is to select the input file to be encoded. To do so, press the Browse button near the Input File field. The standard Open File dialog box will appear.

Select an input AVI file to encode and press OK. If this is a valid AVI file and the system can read the header of that file, then a small information message with the parameters of this AVI file will appear. This popup displays the following information if it is available: frame format, frame rate, number of frames, playback duration, compression type (format code), compression ratio, audio format, and audio frequency.

LSX-MPEG Encoder works significantly better if the input AVI video has little or no compression and low noise level. When creating the input AVI file with a capture card or editing software, try to provide a non-compressed AVI file. If the file must be compressed by some codec, choose the highest possible quality factor and bitrate to avoid artificial noise and distortions on the image.

If the specified file cannot be opened, is not a valid AVI file, or cannot be transcoded to a compliant MPEG file, the appropriate error message will appear. Possible reasons for error messages are:

-	files without an AVI extension

-	files that are invalid or corrupted AVIs

-	files compressed with a codec not present on the system

-	files that do not contain audio data, or contain unsupported audio data

-	files that don’t have frames of even width and height

The boxes for Number of First Frame and Frames to Encode automatically receive values of the first frame (1) and the number of frames to encode from the input file. LSX-MPEG Encoder will allow you to encode a portion of the input file by changing the values in these boxes. Changing the value in the Number of First Frame will cause the Frames to Encode value to change accordingly. For instance, in a 90-frame file, specifying a First Frame of 2 will cause Frames to Encode to adjust to 88. The Number of First Frame must be greater than zero and less than the number of the last frame in the AVI file. The number of the Frames to Encode must then be less than or equal to the number of the last frame in the AVI file, minus the value for First Frame.  If the values entered do not meet these conditions, an error message will be generated.

Only one interval of starting and ending points may be selected. If you need a more complicated operation, like specifying multiple In and Out points, merging several AVI files, or changing Frame Size, use a video editing application to create the appropriate AVI file prior to using the LSX-MPEG Encoder.

Important Note! If you will be using the Batch Processing feature of LSX-MPEG Encoder, you must change Frames to Encode to a value of “1” and save the current Profile before entering Batch mode. This is equivalent to setting the number of frames to “all”. Since all the files you encode will probably be of different lengths (in terms of frames and time), it is important to reset this so the Encoder knows to encode the entire length of all the files in the Joblist.

The user has the choice of multiplexing (retaining video and audio as a single output file) if the source file contains audio. This choice is given by the Audio checkbox. LSX-MPEG Encoder multiplexes both MPEG-1 and MPEG-2 files. The LSX-MPEG Encoder reads audio streams from input AVI files with uncompressed PCM audio format, 8 or 16 bits/sample, mono or stereo, and sample frequency 48000, 44100, 22050 or 11025 Hz. This covers most audio formats used in AVI files. If the LSX-MPEG Encoder cannot accept an audio compression format, it is still able to compress the video stream. If the program cannot accept an audio compression format and audio compression is required, the AVI file audio format can be easily changed to one of the standard acceptable audio formats by using any second party video-editing program.

48 kHz source audio (such as that from DV source) will transcode to a 48 kHz MPEG output audio stream. Audio sample rates of 11.25 kHz, 22.05 kHz, or 44.1 kHz will be encoded as a 44.1 kHz MPEG output audio stream. At this time, LSX-MPEG Encoder does not support conversion between Mono and the three Stereo modes (though the data rate may still be adjusted in the Advanced Audio tab).

When the user selects a new input file, the output file name is created automatically in the Output File edit box. The default output file name will be the same as the input file, but with the extension “.mpg”. The output directory is a global setting that LSX-MPEG Encoder “remembers” from session to session whenever the Browse button is used, even when the application is exited. You can always browse to or type a new output directory.

To change the output file name and/or destination, press the Browse button near the output file field. The standard Save dialog box will appear. The appropriate filename extension for MPEG streams are available here (*.m1v for video only MPEG-1, *.m2v for video only MPEG-2, *.mpg for general MPEG files, or whatever extension you choose for MPEG-2 upon installation) depending on the properties of your current Profile. Select the output file name and directory and press OK. You can also enter the output file name directly into the Output File edit box. If this will result in overwriting an existing file with the same name, a warning box will appear during encoding to prompt you to choose a new filename.

Once you have chosen your input file and specified its output name and format, you are ready to adjust the parameters that will determine the size and the quality of the resulting MPEG file.  All of these parameters together (output file format, video stream data rate, frame rate and size, etc.) make up what is known as an encoding Profile. LSX-MPEG Encoder provides an easy way to name, save and retrieve these Profiles with the Profile Manager. You may choose these parameter settings by using the Profile Manager (as detailed in the following section), or set them manually as detailed here.

To change the output Format, click the MPEG-1 radio button or the MPEG-2 radio button. If you selected MPEG-1, you may also select the VideoCD checkbox, if appropriate. When selecting the standard keep in mind the different properties of these standards.

MPEG-1 is designed for medium quality video and standard CD-ROM data rate. Most existing software and hardware MPEG players on personal computers support MPEG-1. MPEG-1 is generally for video frames sizes equal to or less than 352x288, and a video data rate equal to or less than 2 Mbits/sec.

VideoCD (also known as “White Book” MPEG-1) is actually an MPEG-1 file, but conforms to a specific resolution, frame rate and bitrate to ensure universal playback from VideoCD and some consumer DVD players. This is a popular option in Asia where VideoCD players are popular, but is becoming increasingly popular worldwide now that VideoCDs play in DVD players. In order for the VideoCD option to appear, your settings must match the following requirements of a VideoCD file:

-	Frame size must be either 352x240 or 352x288;

-	Must have audio (mono or stereo), with a sampling frequency of 11, 22, or 44 kHz;

-	MPEG-1 checked as output format;

Please note than in order to complete a VideoCD compliant project, you’ll still require CD-R or CD-RW hardware, as well as software (such as EasyCD Creator by Adaptec or WinOnCD by CeQuadrat) to produce a VideoCD. LSX-MPEG Encoder only produces the MPEG file that can be used as part of the process of creating VideoCDs. Those applications may have other requirements for the MPEG file as specified in their documentation.

The MPEG-2 standard supports high quality video encoding, larger frame sizes, and higher data rates than MPEG-1. Many existing MPEG players do not support MPEG-2, so if you are concerned about compatibility and want the resulting MPEG file to play on many different systems, you should select MPEG-1. LSX-MPEG Encoder now comes with the LSX-MPEG Player for MPEG-2, so you may want to refer others to our website at http://www.ligos.com/ to obtain a Player.

The size and quality of output MPEG files are mostly determined by the MPEG Frame Rate and MPEG Video Data Rate settings.

LSX-MPEG Encoder supports the following frame rates: 23.976, 24, 25, 29.97, and 30 fps (the MPEG standard specifies the following frame rates: 23.976, 24, 25, 29.97, 30, 50, 59.94, and 60 fps -- there is no support in the MPEG specification for other frame rates). If your input AVI file has one of the frame rates in this list, then you’ll generally choose the same frame rate for the output MPEG file. To set the necessary frame rate, select an appropriate item in the MPEG Frame Rate listbox. Note that the program does not automatically reset the matching value of frame rate when a new input file is selected. Also, the number of frames in the output file will not generally match the input file if Frames to Encode or MPEG frame rate has been adjusted.

In the default Constant Bitrate mode, video data rate is set and displayed in the MPEG video data rate box in the main menu. Variable Bit Rate mode is selected and controlled from the Bitrate Control tab of the Advanced Parameters dialog (detailed in the Advanced section on Bitrate Control in this help file). When the user has selected Variable Bitrate, the main window will display “Variable Bitrate Mode” instead of a value.

Video and audio data rate is generally measured in kilobits (Kbits) or megabits (Mbits). Don’t confuse this with kilobytes (KB) or megabytes (MB), which are generally used to denote file size. For future reference, remember that 8 bits = 1 byte. Set the constant video data rate by entering the desired value (in kilobits/sec) in the MPEG Video Data Rate edit box.

Some commonly used video data rates are:

-	“ DVD Quality”; 704x480, 29.97 frames/sec: @4096 Kbits /sec

-	Half D1 (or HHR); 352x480, 29.97 frames/sec: @2048 Kbits / sec

-	VideoCD; 352x240, 29.97 frames/sec: 1123 Kbits/sec

-	Quarterscreen, Internet; 160x120, 24 frames/sec: @400 Kbits/sec

A positive integer between 1 and 102400 Kbits/sec must be entered for the video stream data rate. LSX-MPEG Encoder may not always be able to maintain the specified data rate in Constant Bitrate mode, but will try to keep the average data rate as close to the required as possible. There is always some minimum and maximum limit of data rate that can be achieved with MPEG encoding, depending on frame size, frame rate and content of a particular video file.

Again, all of these parameters together (output file format, video stream data rate, frame rate and size, etc.) make up what is known as an encoding Profile. LSX-MPEG Encoder provides an easy way to save and manage these Profiles in the Profile Manager.

LSX-MPEG Encoder has the ability to call an external application to Preview the Input file currently selected, or Play the Output of an MPEG file once it has been encoded. If you have software capable of playing back the encoded stream (i.e., ActiveMovie, Windows Media Player), you can click on the appropriate button in the Main Window, or from the Action file menu item. A video player window will open and play the stream. The video display windows in the Main Window are not for previewing clips, only for display during the encoding process.


Profile Manager

LSX-MPEG Encoder

The Profile Manager of LSX-MPEG Encoder allows you to use predefined encoding parameters, and create and store your own Profile parameters for later use. It can be accessed from either the pulldown File menu item, or the Open Profile Manager button on the toolbar from the Main Program window.

When the Profile Manager is opened, you’ll see a two-part interface. The left side is a list box that displays predefined and custom MPEG-1 and MPEG-2 Profiles with descriptive names. Each of these individual Profiles are associated with a *.prf file saved in the “..LSX MPEG Encoder 3.0\Profiles” subdirectory (generally hidden from the user within the application). One profile can be selected at a time with the mouse. The right side, Selected Profile Info, displays information on the Profile selected in the Profiles listbox. The information corresponds to some of the settings that are displayed in the Main Program window:

-	Video Stream (format)

-	Video Frame Rate

-	Audio format, layer, frequency and mode

-	Total Data Rate (in kilobits per second)

-	Video Data Rate

-	Audio Data Rate

(Note to users of LSX-MPEG Encoder previous to version 3.0: Each Profile has a matching *.prf file located in the subdirectory “..Profiles”. Users of some earlier versions of the LSX-MPEG Encoder had to manage these *.prf files manually. If you have older Profiles you wish to use in LSX-MPEG Encoder 3.0, they should already be displayed in the Profile Manager. Installation of LSX-MPEG Encoder 3.0 did not overwrite these older Profiles. As a result, you may have some older and newer Profiles with similar/same names or parameters. You may want to rename or delete any duplicates to avoid confusion. If you have older profile files that were kept in another location, you can use the File/Import profile file function on the pulldown menu to add them to the Profile Manager.)

Four buttons along the bottom of the box execute Profile Manager functions:

-	Load Profile (default) – opens the Profile currently selected in the Profiles window (default is first entry) into the LSX-MPEG Encoder Main Window, and returns the user to the Main Window. Double-clicking on a Profile will also load the Profile;

-	Save Current – adds the current settings as displayed in the Main window as a new Profile. The user will be prompted to provide a descriptive name for the Profile;

-	Delete Profile – deletes the Profile currently selected in the Profiles window. This action is undoable. It also clears the Profile from the Main Window if it is currently loaded;

-	Close – escapes from the Profile Manager, and returns the user to the Main Window. This does not undo actions such as Deleting or Renaming a Profile;

There are also right mouse functions in the Profile window associated with the Profile currently selected:

-	Load – opens the Profile currently selected in the Profiles window (default is first entry) into the LSX-MPEG Encoder Main Window, and returns the user to the Main Window;

-	Rename – allows the user to apply a new descriptive name to the selected;

-	Make Copy – creates a duplicate Profile with the same parameters as the Profile selected in the Profile window. The new copy automatically is given the same descriptive name preceded by the words “Copy Of:” (i.e., a copy of “MPEG-1 VideoCD NTSC” is labeled “Copy of MPEG-1 VideoCD NTSC”);

-	Delete - deletes the Profile currently selected in the Profiles window;

LSX-MPEG Encoder comes with 18 predefined Profiles that can be applied to any input source file. Once loaded via the Profile Manager, these Profiles can be easily customized and saved. We suggest that you use the “Save As” option and save customized Profiles with a new name so as not to overwrite the Profiles that originally came with the application. You may also want to make a backup copy of your “Profiles” subdirectory to preserve these settings.

Note that Profile descriptions are recommendations for the type of video that you are encoding. For instance, the Profile called “MPEG-1 (Recommended for SIF 352x240)” is simply a set of properties that work well with an input AVI of SIF resolution. There is nothing that prevents you from loading a Profile for video of a different frame size. You could also load it and change the output format to MPEG-2. The Profiles included with LSX-MPEG Encoder are based on parameters that are popular for different MPEG applications, but are not restricted to those suggestions.

In case you accidentally delete or write over one of the default Profiles, here is a list of them below with some additional information. This first set of four are MPEG-1 Profiles very suitable for Internet use. Using a combination of low data rates and our special “Skip B frames” mode, these profiles produce very compact files suitable for e-mail or web pages.

MPEG-1 (Low bitrate, 10 fps simulated)

MPEG-1, 30 fps (with special “Skip B frames” mode enabled to simulate 10 fps), 190 kbits/sec video data rate, 96 kbits/sec data rate MPEG-1 Layer II audio

MPEG-1 (Low bitrate, 15 fps simulated)

MPEG-1, 29.97 fps (with special “Skip B frames” mode enabled to simulate 15 fps), 498 kbits/sec video data rate, 96 kbits/sec data rate MPEG-1 Layer II audio

MPEG-1 (Low bitrate, 15 fps simulated, variable bitrate)

MPEG-1, 23.976 fps (with special “Skip B frames” mode enabled to simulate 15 fps), variable bitrate mode with a peak maximum of 600 kbits/sec video data rate, average bitrate of 350 kbits/sec, and 96 kbits/sec data rate MPEG-1 Layer II audio

MPEG-1 (Low bitrate, 5 fps simulated, variable bitrate)

MPEG-1, 30 fps (with special “Skip B frames” mode enabled to simulate 5 fps), variable bitrate mode with a peak maximum of 125 kbits/sec video data rate, average maximum bitrate of 75 kbits/sec, average minimum bitrate of 20 kbits/sec, and 32 kbits/sec data rate MPEG-1 Layer II audio

This next set of MPEG-1 Profiles are much more general and popular Profiles based on “good” data and frame rates for different input videos (based on frame size and frame rate).

MPEG-1 (Recommended for QSIF, 176x120)

MPEG-1, 24 fps, 600 kbits/sec video data rate, 96 kbits/sec data rate MPEG-1 Layer II audio

MPEG-1 (Recommended for SIF, 352x240 NTSC)

MPEG-1, 29.97 fps, 1198 kbits/sec video data rate, 128 kbits/sec data rate MPEG-1 Layer II audio

MPEG-1 (Recommended for SIF, 352x288 PAL)

MPEG-1, 25 fps, 1198 kbits/sec video data rate, 128 kbits/sec data rate MPEG-1 Layer II audio

MPEG-1 NTSC (General)

MPEG-1, 30 fps, 1098 kbits/sec video data rate, 112 kbits/sec data rate MPEG-1 Layer II audio

MPEG-1 PAL (General)

MPEG-1, 25 fps, 1098 kbits/sec video data rate, 112 kbits/sec data rate MPEG-1 Layer II audio

This next set of files give you “one-click” access to the settings for VideoCD, both NTSC and PAL standard.

MPEG-1 VideoCD NTSC

MPEG-1 VideoCD, 29.97 fps, 1123 kbits/sec video data rate, 224 kbits/sec data rate MPEG-1 Layer II audio

MPEG-1 VideoCD PAL

MPEG-1 VideoCD, 25 fps, 1123 kbits/sec video data rate, 224 kbits/sec data rate MPEG-1 Layer II audio

The remaining seven Profiles are best used for video larger than 352x288, and for higher data rates than listed above. They default to MPEG-2, and cover resolutions from Half-Horizontal Resolution (HHR, or Half D1) up to fullscreen. Also included is an MPEG-2 Profile using the new Variable Bitrate mode that produces excellent fullscreen quality in a compact file size.

MPEG-2 (Recommended for HHR, 352x480 NTSC)

MPEG-2, 30 fps, 2048 kbits/sec video data rate, 192 kbits/sec data rate MPEG-1 Layer II audio

MPEG-2 (Recommended for HHR, 352x576 PAL)

MPEG-2, 25 fps, 2048 kbits/sec video data rate, 192 kbits/sec data rate MPEG-1 Layer II audio

MPEG-2 (Recommended for NTSC Full Screen)

MPEG-2, 29.97 fps, 4096 kbits/sec video data rate, 224 kbits/sec data rate MPEG-1 Layer II audio

MPEG-2 (Recommended for PAL Full Screen)

MPEG-2, 25 fps, 4096 kbits/sec video data rate, 224 kbits/sec data rate MPEG-1 Layer II audio

MPEG-2 (Sample VBR profile for Full Screen)

MPEG-2, 29.97 fps, Variable Bitrate with maximum peak 6000 kbits/sec video data rate, maximum average of 3000 kbits/sec, minimum average of 1500 kbits/sec, 224 kbits/sec data rate MPEG-1 Layer II audio

MPEG-2 (Main Profile @ Low Level)

MPEG-2, 30 fps, 3906 kbits/sec video data rate, 112 kbits/sec data rate MPEG-1 Layer II audio

MPEG-2 (Main Profile @ Main Level)

MPEG-2, 30 fps, 14648 kbits/sec video data rate, 112 kbits/sec data rate MPEG-1 Layer II audio

Again, you can load the Profile, load your input video, and make any changes you wish. These Profiles are simply meant as guidelines or starting points. If you want to change any other encoding parameters (such as audio format or data rate, bitrate options, header information, etc.), press the Advanced button. The Advanced Parameters dialog box will appear. See the next section about using the Advanced Parameters dialog box.


Advanced Parameters

LSX-MPEG Encoder

The Advanced Parameters dialog box appears when the user presses the Advanced button on the main window. It contains a tabbed dialog box with combinations of up to 15 individual dialog boxes (property pages): Motion Vectors, Sequence, Performance, Input, Processes, Bitrate Control, Sync, Edges, Headers, Audio, Files, System, MPEG-1, MPEG-2 and Special. Use the tab bar or mouse to select the appropriate property page. These options are available to do two things: one, allow advanced users to finely tune their MPEG output for best results in terms of quality and compression, and; to provide parameters that help produce files compatible with the wide range of software and hardware MPEG players available on the market.

When required data is entered press OK to confirm changes and close the Advanced Parameters dialog box. The program will ensure all data values are valid, and if some are not valid then an appropriate message will appear and the dialog box will remain opened to let the user correct the data. Press the Cancel button to quit and not save changes.

Although there are a total of 15 Advanced Parameter dialogs, availability is determined by the input source file and settings in the main window. For instance, in a case where the AVI file does not have an audio component, there is no Audio or System property page displayed in the Advanced Parameters box. Likewise, if MPEG-2 encoding is selected there will not be MPEG-1 or System tabs displayed, as they apply to MPEG-1 encoding only.

Advanced Parameters tabs:

Motion Vectors

Sequence

Performance

Sync

Headers

Audio

Files

System

MPEG-1

Input

Special

Processes

Bitrate Control

Edges

MPEG-2


Motion Vectors Property Page
Advanced - Motion Vectors

LSX-MPEG Encoder

Motion Vectors Property Page

This dialog box prompts the user for maximum values of horizontal and vertical motion vectors for P and B frames. The right choice of maximum motion vector values helps to achieve the best possible quality for a particular data rate. There are no general rules on how to choose maximum motion vectors. If the motion vectors are too short, this prevents the encoding of a good quality image. If motion vectors are too long, this may also reduce the quality of the image as well as take more time to encode. For a new input file you can encode the first time with default values (32 for P frame and 16 for B frame) and later try to adjust the values. Optimum values are usually in the range 16 - 32.

The up and down arrows near the edit boxes for maximum motion vectors increase and decrease values by minimum steps equal to 8.

NOTE: maximum motion vectors must be positive values (multiples of 8). If you enter 0 or a negative value or not a multiple of 8, the Encoder will generate an error message.


Sequence Property Page
Advanced - Sequence

LSX-MPEG Encoder

Sequence Property Page

This dialog box prompts the user to set the amount of P and B frames in the output file (see Parameters that affect quality and performance). The user can increase or decrease the number of P frames between the nearest I frames and the number of B frames between the nearest P frames. Current frame sequence settings represents the sequence of frames that is specified. You can see how the string changes when you change values in the Number of P frames and Number of B frames fields. You cannot directly edit the frame sequence string. There are three buttons on the bottom of this dialog box. These buttons help the user to set P and B frame numbers for one of three possible standard sequences: I frames only, I and P frames (no B frames), and default sequence (number of P frames 3, number of B frames 2). The default sequence is suitable in most cases. The optimum value for the number of B frames is 2 or 3. If you want to achieve the best quality for a limited data rate then you may want to increase the amount of P frames up to 10 or 12.

NOTES:

-	“ I frame only” is useful to create files that may require editing. By it’s nature, full IBP MPEG is difficult to edit with frame accuracy in most editors.

-	B frames depend on P frames, so you cannot set a non-zero amount of B frames and a zero amount of P frames.

-	The maximum setting for B frames in the sequence is 30.

-	Settings of “I frames only” or “I and P only” will create a larger file that is less efficient, and may actually suffer in quality or playback.

The ability to modify GOP sequences is very useful when used in conjunction with the Special tab to utilize our special “Skip B frames” mode. For more information on how to change frame sequencing in order to achieve faster encoding, smaller file size, or higher quality, see the sections on skipping B frames in Advanced User Questions and Achieving Best Results.


Performance Property Page
Advanced - Performance

LSX-MPEG Encoder

Performance Property Page

This dialog box prompts the user to select one of the five modes for motion estimation: "Very fast, lowest quality", "Fast, low quality", "Normal speed, normal quality" (default), "Slow, higher quality", "Very slow, maximum quality". To choose an appropriate performance mode, press the corresponding radio button. “Slow” mode often provides the best quality of encoding, but our motion estimation algorithm usually provides sufficiently high quality with Normal speed. It depends on the statistics (content) of a particular video stream, data rate, and maximum motion vectors specified. In most cases, Normal mode provides great quality and sufficiently fast encoding.

The last checkbox, Calculate image quality when encoding is in progress, enables the program to calculate the average quality of the entire output video stream and quality characteristics of the last encoded frame. These characteristics may be useful when choosing the best parameters of MPEG encoding for a particular input file. Calculation of quality takes some additional processor resources, so you may prefer to disable it to achieve faster encoding. It is enabled by default. You can see the representation of values of average and last frame quality during the process of encoding if it is enabled. They are also presented in the final message box that appears when encoding is completed.

NOTE: There is no common definition of what is a measure of quality of encoded video. In this program, quality measure is based upon the sum of square values of differences between the original pixel on the input frame, and the corresponding pixel on the output frame. This value is transformed in the program so that the maximum possible quality represented to output value is 100, the minimum possible quality represented is 0. Value of quality characteristics of 40 or more usually corresponds to “Good” subjective image quality.


Sync Property Page
Advanced - Sync

LSX-MPEG Encoder

Sync Property Page

The Sync Parameters Property page has radio buttons that allow the user to choose to keep original duration time (default) or keep original number of frames.

If the user chooses to Keep the original duration, the length of time a particular segment of the original AVI file will play for the same amount of time in the output MPEG file. This is called audio-video synchronization (sync), and the user must choose to keep original duration when audio and video information must be synched. If there is no audio information to sync to the video, or if you choose not to include the audio of an AVI file into the output MPEG file, then you can choose to Keep the original number of frames. This will encode the file as you have specified, but the playback duration of the file may be different from the original AVI file. This option is disabled when audio is selected in the Main Window to be encoded.


Headers Property Page
Advanced - Headers

LSX-MPEG Encoder

Headers Property Page

The Headers Property page has dropdown boxes that allow the user to specify closed GOP (Group of Pictures) options and to add Sequence Headers to MPEG files. Use of these is optional, and related to the application you intend to use for your MPEG streams. For instance, closed GOPs make it easier for you to edit MPEG files, and DVD authoring requires the use of sequence headers. If your application is having a difficult time using your MPEG files, you may need to experiment with one or a combination of these options.

In an MPEG file, every GOP has a flag indicating whether it is an “open” GOP or a “closed” GOP. An open GOP has B frames the may be dependent on P frames outside of the GOP.  A closed GOP contains B frames that only rely on P frames within the same GOP for prediction. Although this is generally not important in decoding, it is very important in MPEG editing. Editing is often a frame-by-frame process, and the IPB structure of MPEG can make the concept of “frames” a difficult one. Closing the GOPs, or every N number of GOPs, can make editing MPEG easier.

By default, LSX-MPEG Encoder produces MPEG files where only the first GOP is closed. You can choose to close all GOPs, but it is not recommended and probably unnecessary. Suggested ranges are available to close one out of every 2 to 10 GOPs. Be aware that closing GOPs can increase file size, and reduce quality and performance. If you plan to edit your MPEG streams, we suggest a value such as closing 1 out of every 4 GOPs.

Sequence headers are codes within the MPEG stream that provide hints about the nature of the stream for MPEG decoders. A sequence header includes information such as a start code, the horizontal and vertical size, frame rate, aspect ratio, bit rate, as well as MPEG-2 extensions about profile and level information, chroma format, and other characteristics about the video to follow the header. Certain decoders look for this information, and certain applications of MPEG (for instance, systems that are always broadcasting an MPEG stream) may require sequence headers. In fact, if you are creating MPEG-2 files for use in DVD authoring, be aware that every GOP requires a sequence header.

LSX-MPEG Encoder gives you the option to put a sequence header only at the beginning of a stream (default), before every GOP, or at regularly specified intervals before N number of GOPs.


Audio Property Page
Advanced - Audio

LSX-MPEG Encoder

Audio Property Page

This dialog box prompts the user for audio mode and data rate information for the MPEG-1 Layer II portion of the output stream. This page only appears when Encode Audio is selected from the Main Window.

Mono, Stereo, Dual Channel, or Joint Stereo specifies the mode of the audio stream. Note that at this time, LSX-MPEG Encoder does not support conversion between Mono and a Stereo mode.

The Audio stream data rate is specified in kilobits per second, and generally defaults to a setting suitable for the Input stream audio.

NOTE:

- VideoCD requires a setting of 224 Kbits/sec

- MPEG for DVD requires Mono 32 to 192 Kbits/sec or a Stereo mode 64 to 384 Kbits/sec

The LSX-MPEG Encoder reads audio streams from input AVI files with uncompressed PCM audio format, 8 or 16 bits/sample, mono or stereo, and sample frequency 48000, 44100, 22050 or 11025 Hz.  48 kHz source audio (such as that from DV format source) will transcode to a 48 kHz MPEG output audio stream. Audio sample rates of 11.25 kHz, 22.05 kHz, or 44.1 kHz will be encoded as a 44.1 kHz MPEG output audio stream.


Files Property Page
Advanced - Files

LSX-MPEG Encoder

Files Property Page

This dialog box prompts the user for temporary output video and audio files. The user has the choice of browsing for a previous filename or can directly input a filename into the space provided. Since these files are used for intermediate encoding information, the user has the option to retain these temporary files or have them deleted later (default). Leaving the temporary audio file following encoding is a handy method for creating standalone MPEG-1 Level II audio stream files (*.mp2).


System Property Page
Advanced - System

LSX-MPEG Encoder

System Property Page (MPEG-1 files only)

This dialog box prompts the user for MPEG-1 system stream parameters. The user is queried about packet size, packets per pack ratio, size of video buffer, and size of audio buffer. The user is also asked if the encoding process should use a fixed bitrate in the multiplexed output stream.

The Pack Size must be less than or equal to 4096 bytes. Packets per pack ratio must be less than or equal to 4. Video buffer size must be between Pack Size/1024 and 46 Kbits. Audio buffer size should be between Pack Size/1024 and 4 Kbits.

Depending on the visual content of an input file and the intended size of the output file, it may be necessary to have the LSX-MPEG Encoder add some “padding” to the output stream to achieve a consistent, fixed bitrate. This is especially true with files with very high bitrates. If your output file has problems playing back in an MPEG player, or if you’re unhappy with the quality, you may want to try re-encoding with the Constant bitrate checkbox (off by default). Note that may increase the output stream file size by up to 20%.


Special Property Page
Advanced - Special

LSX-MPEG Encoder

Special Property Page

This dialog box prompts the user for information concerning skipping B frames to increase the image quality, especially on files with low bitrates. Options that can be chosen are Normal mode (default, no B frames skipped), Skip 1 B frame after I or P frame, Skip 2 B frames after and before I or P frame, and Skip all B frames.

AVI files may have a frame rate that does not match any of the available MPEG frame rates (for instance, 10 fps, 12, fps, 15, fps, etc.). The MPEG standard specifies the following frame rates: 23.976, 24, 25, 29.97, 30, 50, 59.94, and 60 frames/sec. There is no provision in the standard for support of frame rates lower than 23.976 frames/sec.

The LSX-MPEG Encoder program can create MPEG files with frame rates: 23.976, 24, 25, 29.97 and 30 fps. Because many AVI files have frame rates lower than these, many of the input frames will be duplicated to obtain one of the standard MPEG frame rates. The special Skip B Frame modes eliminate these duplicated frames, and reduce the data rate and apparent frame rate in the process. It does this by skipping most of macroblock data on the specified B frame. For example, when the input format is 640x480, the application codes only 60 bytes for an MPEG-1 skipped B frame, and about 288 bytes for a skipped MPEG-2 B frame. When decoded by a standard MPEG player, the skipped B frames will repeat the picture from the nearest P frame in the sequence.

The ability to skip B frames is very useful when used in conjunction with the Sequence tab. For more information on how to change frame sequencing in order to achieve faster encoding, smaller file size, and higher quality, see the sections on skipping B frames in Advanced User Questions and Achieving Best Results.


MPEG-1 Property Page
Advanced - MPEG-1

LSX-MPEG Encoder

MPEG-1 Property Page (MPEG-1 files only)

This dialog box asks the user to decide whether to enforce Constrained Parameters for encoding an MPEG-1 video file or not. Many MPEG-1 decoders (hardware and software players) may require the MPEG-1 stream to meet the requirements of the Constrained Parameters section of the MPEG-1 specification. Checking this overrides any specific settings you may have in the current Profile which do not meet those requirements. This will also allow the Encoder to provide warnings about specific settings (frame size, data rate, etc.) that may not meet the Constrained Parameters specification.

Also included is a box for a value to set the MPEG-1 aspect ratio code. Adjust this based on the aspect ratio of your input source file, as required by the target decoder (the default setting of “1” for square pixels should be used for most sources). Please note that this value corresponds to the MPEG-1 specification parameter, pel_aspect_ratio, and these values are not equivalent to the MPEG-2 aspect_ratio_information values.

It is important for these options to match settings you have made elsewhere in the application. For instance, if you set Constrained Parameters as “on”, make certain that items such as Frame Size and Video Data Rate in the Main Window match the Constrained Parameters specifications. LSX-MPEG Encoder will generate warning messages if you attempt to encode with mismatched parameters. For more information on MPEG-1 Constrained Parameters, see the section on Constrained Parameters, Profiles & Levels.


Input Property Page
Advanced - Input

LSX-MPEG Encoder

Input Property Page

This dialog box gives you options to process the input file prior to encoding to improve quality. Generally, you'll want to leave these options at their default values, but if you have an input file that results in output with unacceptable quality, you may want to experiment with changes here. Enabling these filters will generally slow down the encoding process.

The first section deals with Filter operations. Enabling prefiltering can improve picture quality by reducing visual "noise" in the stream. The program includes two different kinds of filters, Median filter and Low Pass filter. Both of them can help to reduce noise, but work differently.

The Low Pass filter removes high frequency components of the picture, It reduces noise, but also removes small image details and makes image look less sharp. It works by applying linear convolution matrix to the area near every pixel.

The Median filter usually helps to reduce random noise without removing small details or reducing sharpness of picture. It is a complicated nonlinear filter. It works by sorting values of all pixels near the specified pixel and selecting the median value. The standard method of median filtering does not allow adjustment of the partial "level" of filtering. This program uses a modified version of the median filter method that allows the user to set a numerical "level" value.

The numerical value from 1 to 100 can be specified for the Low Pass and Median filtering. This value determines the "level" of filtering. Choosing larger values result in better noise reduction, but may also result in reducing image sharpness. Experiment with these numbers against specific input files until you achieve the desired result.

The next two functions, Deinterlace input picture and Detect inverse telecine, are related to one another, and are part of the revised and improved Deinterlace functions of LSX-MPEG Encoder 3.0. The process of drawing a video frame by alternately drawing the rows of each field is known as interlaced scan, or interlacing. Two fields make up each frame, and this is the method of delivery for video over broadcast systems such as NTSC and PAL. Progressive scan, the alternative to interlaced scan, is when only complete frames are drawn on the screen. This is used on computers, where high quality is important and the application is not tied to an interlaced broadcast standard.

For instance, even though NTSC video is thought of as 30 frames per second, it is actually made up of 60 half-frames (known as fields) displayed one after the other per second. Each half-frame is consecutive black/video lines that, when interlaced, create full frames. Fullscreen video source is often captured as interlaced video, which exhibits jagged lines when played back on a computer monitor. These problematic “jaggies” appear because odd and even scanlines of the captured picture originated on different video fields of interlaced source video signal.

The new Deinterlace functions of LSX-MPEG Encoder allow the user to create better quality progressive video from the interlaced captured source. Deinterlace input picture is used to reduce jaggies that often accompany footage captured at fullscreen resolution (640x480 or larger), or SIF resolution video from an NTSC video signal. The Deinterlace function essentially interpolates odd scan lines using the pair of nearest even scan lines.

Note that Deinterlace works only when vertical image size is larger than 288 pixels, and may work best when Detect inverse telecine is also enabled (see below). It is recommended that you enable this option whenever transcoding fullscreen video source that was originally captured as interlaced (check your capture card hardware and software settings). The Encoder will not display the Deinterlace option if the vertical height of the input file is less than or equal to 288 pixels.

Detect inverse telecine refers to telecine, the process of transferring a film master (24 frames per second) to NTSC video (30 interlaced frames per second), known as “3:2 pulldown”. During that process, video fields are duplicated which can make conversion to MPEG inefficient, but may be necessary for certain types of motion in scenes. The Detect inverse telecine function (“on” by default in Profiles for NTSC source video) enables the Encoder to try to detect these duplicated frames, and approximately “undo” the telecine process. When this option is enabled, it usually results in better picture quality, reduced file size, and slightly increased speed of MPEG compression.

When Detect inverse telecine is enabled, the Encoder performs minimal encoding of B frames with no picture change information (like the “Skip B frames” modes in the Special tab). Detect inverse telecine analyzes frames for duplication caused by 3:2 pulldown, but may not always be able to do so correctly (depending on the amount of noise in the input video). You may find it more accurate (but more time consuming) to specify the number of frames in the Sequence and use one of the Special "Skip B frame" modes to ensure that the correct duplicated input frames will be skipped.

Detect inverse telecine is generally only effective (and useful) if input video was originally transferred from 24 frames per second film to NTSC video format. It is not recommended for PAL source video (25 frames per second), or video that has never been processed with 3:2 pulldown.

When both Detect inverse telecine and Deinterlace input picture are enabled, the Encoder will attempt to recreate its best approximation of the original progressive frames from the interlaced fields. In order to do so, the input AVI file must also have a vertical resolution greater than 288 pixels and a frame rate of NTSC standard 29.97 or 30 fps. Deinterlace input picture cannot rebuild the fields for telecined material if the Detect inverse telecine is disabled.

PLEASE NOTE: These Deinterlace filters do not automatically convert the 29.97/30 fps source video back to its original 24 fps. The purpose of these filters is to produce a file that is more efficient in terms of image quality and size. Even if you set the MPEG Frame Rate to 24, it is likely that the correct frames will simply be dropped to meet that reduced frame rate. Perfect detection of duplicated frames, and conversion back to the original frame rate is nearly impossible due to factors such as motion and video noise in the source. You may be able to manually convert back to 24 fps by using the “Skip B frames” modes in the Special tab. This requires careful examination of the AVI source file to locate “the pattern” of duplicated frames caused by 3:2 pulldown. If the frames are repeated on a regular basis, you can manually set Frame Rate, Sequence, and Special "Skip B frame" options to ensure that the correct duplicated input frames will be dropped.

Again, enabling any of these Input filters will generally slow the encoding process.


Processes Property Page
Advanced - Processes

LSX-MPEG Encoder

Processes Property Page

This dialog box allows the user to activate parallel processing options of the LSX-MPEG Encoder to increase the speed of encoding, or distribute other Encoder functions to other processors. The optimal combination of settings depends on the actual system configuration and encoding conditions. When a change is made to these options, the setting is saved as part of the global application settings and is not saved as part of the current Profile. These options do not affect the output file, only the speed of encoding. Clicking on Default will set all dialog options to the automatically detected recommended mode.

Single processor systems running Windows 95/98 can use the option Enable parallel read of input file. This option can especially speed up the encoding of large files that contain uncompressed raw RGB or YUV format data. All other options are grayed out in the Windows 95/98 environment.

Other options appear when the computer has two or more processors running under the Windows NT operating system version 3.51 or later. With proper use of these options on dual processor system, it is possible to nearly double encoding speed.

Setting a value for Amount of parallel threads for motion estimation allows the user to select an optimal parallel processing mode when doing the motion estimation. The optimal value is usually the number of processors in system. Larger values may possibly somewhat increase or reduce the speed, depending on system and encoding parameters. All other parallel processing options increase the encoding time, and are recommended only for systems with more than two processors.

It is possible, but unlikely, that using Parallel read of input data might cause a system error is some configurations. In that case, disable Parallel read of input data before encoding again.


Bitrate Control Page
Advanced - Bitrate Control

LSX-MPEG Encoder

Bitrate Control Property Page

LSX-MPEG Encoder has two distinct modes for controlling video data rate: the default Constant Bitrate (CBR) and Variable Bitrate (VBR). It is recommended that you reserve use of VBR for MPEG-2 files, as some MPEG-1 players are capable of playing only CBR MPEG-1 files. In CBR, video data rate is completely controlled and displayed from the MPEG video data rate setting in the Main Window. VBR mode is selected and controlled from this Bitrate Control tab. When the user selects Variable Bitrate, the main menu will display "Variable Bitrate Mode".

As the name suggests, CBR encodes the video at a fairly consistent data rate throughout the encoding process, regardless of the amount of information or motion within the video. LSX-MPEG Encoder will attempt to match the average data rate to the assigned data rate as close as possible. There is always some minimum limit of data rate depending on input frame sizes, frame rate, and content of a particular video file.

VBR mode can produce better picture quality than CBR mode for the same output file size, or a smaller file size for the same image quality. It is achieved by dynamically allocating more bits for the complex pictures or faster moving images, and less bits for simple or slow moving images. The VBR mode also allows the user control over quantization to smooth variations and prevent low quality frames in highly active video sequences, which is almost unavoidable when using CBR. In video encoding, quantization determines the extent of frequencies to be analyzed in the video.

There are three VBV (buffer Verifier) modes, each requiring the user to enter a value for Maximum bitrate, the absolute peak limit of the bitrate. It is recommended that the value be no more than the maximum bitrate associated with the appropriate MPEG-2 level and profile. There may be other considerations as dictated by the target platform for the resulting stream. For instance, MP@ML MPEG-2 video has maximum data rate specified at 15 Mbps. DVD-Video uses MP@ML MPEG-2, but the maximum data rate for DVD is specified to be 9.8 Mbps. Be sure to take your target platform into account when setting Maximum bitrate.

The three Rate Control Modes are:

-	Simple variable bitrate mode, which requires only one additional value, that of the Average bitrate you’d like the stream to maintain. This value would be similar to the value for Constant Bitrate mode.

-	Constant quantization scale mode, which does not allow you to specify an average bitrate, but rather requires a value for quantization. Lower settings here equate to less noise and fewer extreme video frequencies being encoded, and therefore better quality video. This is a somewhat experimental process, as it can result in large video files (controlled only by the Maximum bitrate setting above) and longer encoding times, but quality results are almost guaranteed. The quantization scale can be summarized as:

1 – 3: excellent image quality, results in larger video data rates

4 – 5: very good image quality

6 – 8: medium image quality

9 – 11: low image quality, lower data rates

11 – 31: very low image quality, suggested only for very low data rates

-	Optimized quantization scale mode allows you to choose both the quantization value, as well as set an Average Maximum and an Average Minimum value for the bitrate. Average minimum bitrate is the data rate that you want the encoder to maintain when dealing with simple or slow moving segments of video. Average maximum bitrate is the data rate that you want the encoder to use when dealing with complex or fast moving sequences of video. Average Maximum will always be less than Maximum bitrate and Average Minimum must be less than Average Maximum. Select quantization on the basis of the quality you’re trying to achieve. Try to keep the setting between “2” or “3” for best results, as this limits the encoding of extreme (often imperceptible) frequencies. If you find performance during encoding is suffering, try changing the value to “4” or “5”.

For more guidance on values to use in VBR mode, see the section Achieving Best Results.


Edges Property Page
Advanced - Edges

LSX-MPEG Encoder

Edges Property Page

The Edges Property page allows you to cover portions of the top and/or bottom of the image with a black line, at a thickness you specify. This feature is especially useful when dealing with video source that has annoying blinking or colored lines at the edges of the image. This is most often seen in video captured from VHS source tape, and sometimes introduced by low-priced capture cards.

It can also be used to place thick black borders along the top and bottom of your video, giving it the appearance of a “letterboxed” widescreen movie.

Specify the number of “lines” of black to be added to the bottom and/or top of your output video. Default value for both is zero. The total value for both cannot be greater than the frame height.

NOTE: This does not change the frame size or aspect ratio of your video. It simply applies a border that covers up the image underneath.


MPEG-2 Property Page
Advanced - MPEG-2

LSX-MPEG Encoder

MPEG-2 Property Page (MPEG-2 files only)

This dialog box presents choices that correspond to the MPEG-2 specification of bitstream syntax profiles (Simple, Main, SNR, Spatial, High), and levels (Low, Main, High 1440, High) representing constraints on bitstream values. These “comments” are included with the MPEG-2 output stream, and it is strongly recommended that you specify these options according to the characteristics of the input source file and the intended use of your final output file. Available choices are:

•	Main Profile at Low Level

•	Main Profile at Main Level (default)

•	High Profile at High 1440 Level

•	High Profile at High Level

Also available for customized setting are the Source video format (default NTSC) and the setting for the appropriate Aspect ratio (default 4:3).

Source video format corresponds to the MPEG-2 Sequence display extension video_format, and should be set as one of the following, based on the type of original source:

•	Component

•	PAL

•	NTSC

•	SECAM

•	MAC

•	Unspecified

Aspect ratio corresponds to the MPEG-2 aspect_ratio_information sequence header setting, and specifies either a square (1:1) Pel Aspect Ratio value of “1”, or an Image Aspect Ratio describing the ratio of picture width to height. Valid values for Aspect Ratio are:

•	1 – 1:1 (square)

•	2 – 4:3

•	3 – 16:9

•	4 – 2.21:1

Although the MPEG-2 specification does not require this information be included in the stream, many MPEG-2 decoders and applications do require that this correspondence be present and match the characteristics of the file itself. It is important for these options to match one another, and settings you have made elsewhere in the application. For instance, if you set Source video format as PAL, make certain that items such as Frame Size and Frame Rate in the Main Window match the PAL specifications. LSX-MPEG Encoder will generate warning messages if you attempt to encode with mismatched parameters. For more information on Profiles and Levels, see the section on Constrained Parameters, Profiles & Levels.

The MPEG-2 Multiplex Parameters setting (checked off by default) allows the LSX-MPEG Encoder to “pad” the file with padding packets to maintain a fixed bitrate in the multiplexed stream, often helpful with large streams with high bitrates. For MPEG-2 streams with low bitrates, or files truncated from the original source files (that is, you changed the Frames to encode box), you may wish encode the file leaving this multiplex option unchecked.


Encoding

LSX-MPEG Encoder

The LSX-MPEG Encoder takes input video streams from Windows AVI video files. A video codec appropriate to the input file must be installed on your system to decompress the particular video-encoding format. The video codec must be able to decompress video frames to RGB (24 bits/pixel) or palette-based 8 bits/pixel uncompressed bitmaps. Most video codecs in Microsoft Video for Windows can decompress to at least one of these formats. Some rarely used or older codecs cannot, however, be used as input for the LSX-MPEG Encoder. In such a case you can use any video editing software to convert that AVI video file to some other video compression format that the encoder understands. Some video codecs (for example some Motion-JPEG video codecs) may require a special kind of video compression and video capturing hardware be installed on your system to be able to decompress that particular video file format.

LSX-MPEG Encoder cannot crop or scale input video frames. If you wish to encode MPEG files with frame sizes different from the input file, then use any video editing program to convert (crop or scale) the image format before encoding.

The program can encode an AVI file with any even frame width and height values. If one of the values in the input file is not even, then the program will display an error message informing you that the file cannot be encoded.

There are some other limitations (image width/height, frame rates, etc.) that may apply due to compliance with the MPEG standard itself. In general, MPEG-1 video stream parameters must comply with the Constrained Parameters bit stream in order to be played by most MPEG-1 players. If the parameters of a file to be encoded to MPEG-2 do not correspond to certain MPEG-2 standards or Profiles and Levels, the user may receive warning messages regarding non-standard picture size, frame rate, etc.. This does not mean that the file cannot be encoded, but that the resulting file may not fall within MPEG-2 compliant standards, and may not playback in MPEG-2 players.

LSX-MPEG Encoder cannot convert audio from one format to another (for instance, stereo to mono). If the advanced settings conflict with the audio format of the source file, the application will show a warning box when it begins to encode the audio. Audio will be encoded, but only in the same format as the original.

Once all parameters have been set in the Main Window and Advanced Parameters dialog, the user can begin encoding from the pulldown Menu item or by pressing the Start MPEG Encoding button on the toolbar. If the name of the target output file already exists, the user will be prompted to rename or continue. The Encoder may also present warning messages if the options selected somehow conflict with each other, might result in a low quality file, or will result in a file that may not conform to MPEG standards. Again, these messages do not mean the file cannot be encoded, it simply means that some decoders or applications may have a difficult time with the resulting file. For best results, follow the advice presented in the warning messages.

If all conditions to begin encoding are met, the application will begin encoding the video portion of the stream. By default, the Output MPEG Video Stream display will replace the LSX-MPEG logo, and you can study the output video as encoding is taking place. If you have chosen to also display the Input Stream frames of the AVI, the two stream displays will be shown side-by-side for comparison.

A new section of the interface, MPEG Video Encoding in Progress, will appear below. Meters will display a frame by frame accounting as each frame is encoded, and show information on image quality, current frame quality and elapsed encoding time. The application will then show a meter for the encoding progress of audio, followed by a meter for the multiplexing of audio and video, if applicable.

At any time during the encoding process, the user can Stop the process by either pushing the Stop button in the progress display, the Stop button on the toolbar, or the Stop Encoding menu item. The user will be prompted to confirm. The user can also choose to pause the encoding process with the Pause button on the toolbar, or Pause Encoding from the menu. To resume encoding, press Pause again.

When finished, the Multiplexing Completed popup is displayed, presenting a summary of information regarding the process. See the section in the FAQ for a complete explanation of the calculation of image quality.

Depending on the settings of the Files property tab in Advanced Parameters, the temporary files for audio and video will be deleted at this point.

If the user has software capable of playing back the encoded MPEG stream, they may do so by clicking on the Play Output File button in the Main Window, or from the Action menu. A video player window will popup and play back the stream:

If an MPEG decoder component is not present, the following (or similar) message will be displayed:

MMSYSTEM can’t play specified MPEG file. File not found or has unsupported video format.

Possible reasons: MMSYSTEM may not have MPEG playback driver properly installed or playback device is not able to play MPEG file with specified parameters.


Batch Processing

LSX-MPEG Encoder

LSX-MPEG Encoder includes a Batch Processing feature for unattended encoding sessions (specified by a Joblist) to encode multiple files, even with multiple Profiles. That means, for instance, that you could encode a series of different videos that are output in MPEG-1, VideoCD, and MPEG-2, all in the same session!

Since multiple files will probably be of different lengths (in terms of frames and time), it is important to first reset Frames to Encode so that Batch Processing can encode the entire length of all the files specified in the Joblist. In the Main Window, change Frames to Encode to a value of “1” (if necessary). This is equivalent to setting the number of frames to “all”.

Once Frames to Encode has been set to “1”, select "Batch Processing" from the File Menu or toolbar. If you’ve made any unsaved changes to the Profile currently loaded, you will first be prompted to Save these changes. Keep in mind that saving these changes overwrites the currently loaded Profile. After the prompt, the Batch Processing dialog box will open.

The interface is broken into three sections. The left top section is where you select the Profiles and AVI files that make up the Joblist. The right top section is a display of your Joblist, and buttons to Save or Load a previously created Joblist. The bottom section specifies options for the output of the encoded files.

The first section is a three-step process that allows you to first select a previously defined Profile, and then select multiple AVI files from multiple locations with that Profile. You can then repeat those steps if you wish to use more than one Profile.

To Create the Batch Conversion Joblist, begin with Step 1 – Select Profile to be used. The dropdown box contains the list of Profiles in your library, including those you may have custom created. Select a Profile with the mouse cursor and click on the Add current Profile to the Joblist button. You’ll see that the name of the Profile now appears in the list to the right. If the required Profile does not exist, a new one will have to be created by leaving Batch Processing mode. If no Profile is selected at all, the Profile currently loaded into the Main Window will be used.

Next, Step 2- Select AVI files for encoding to this Profile by clicking on the Browse button. A file dialog opens to allow you to browse around drives to locate files. Select specific files (only AVI files are a valid input format for LSX-MPEG Encoder) by browsing and left clicking on them. Click on the Add button to include them in the Joblist.

Multiple files can be selected. Press <SHIFT> to select contiguous (side-by-side) files. Press <CTRL> to select non-contiguous files.

Clicking on the “Add” button will add the selected file(s) to the Joblist window in the Batch Processing dialog box, indented underneath the Profile. You may continue to browse to different directories to choose your source files.  Be certain not to select files with the same names from different directories, as this will cause the conversion utility to overwrite those files. When finished, click on the Done button to return to the Batch Processing dialog.

At this point, Step 3, you can return to Steps 1 and 2 to add more Profiles and accompanying AVI files. The user can delete any files from the Joblist by selecting them and hitting the Delete key. If you delete a Profile, it does not automatically delete its accompanying AVI files.

Once you finish a Joblist, you can Save your Joblist as a Batch List file (*.btc). You can also Load a different Joblist into the display window (overwriting the current contents). This is especially useful for long encoding projects, tasks that have to be repeated, or projects that need to be interrupted. It also gives you some room for experimentation without losing time trying to recreate a Joblist you’ve already used before. For instance, you may come back from a long Batch Processing session to find out that you’re not happy with the quality of a few of the output files. You can make changes to the Profiles involved, then run parts of that Joblist again.

Note: The saved Joblist is simply a collection of the filenames in a text file, not the AVI or Profile files themselves. If you make a change to a Profile outside of a Batch session, or rename/relocate and AVI file, the Batch List may need to be adjusted to reflect changes to the files it’s referencing.

Now the user must select or create the Output Folder. Click on the Browse Button, and LSX-MPEG Encoder will open the Select Folder dialog box. Use the dialog box to select or create the destination folder for the new files. If left unspecified, the application will generate an error message. Alternatively, you may directly type a destination path into the Output Folder box.

To override any error messages and pauses during the conversion, check off the Suppress Error Messages checkbox. If this option is not checked off, batch processing will proceed unless the application encounters a problem file. An error message dialog will be displayed, and the user will need to click OK to continue. Although Suppress Error Messages will keep error messages from being displayed, an error log is created as a text file (message.log) in the output folder, listing any warnings that may have been encountered. This file is overwritten each time a new batch conversion job is initiated. An option to view it following a completed conversion session is presented to ensure that encoding was successfully completed, or report possible problems.

To begin Batch Conversion of the files selected, click on the Start Button.

LSX-MPEG Encoder will begin the batch conversion and display status bars and view windows for each file to be encoded, one after the other. To abort the batch conversion, click on the Stop button.

Files are saved with the name of the original file, but with the appropriate Profile extension (i.e., source input file “myclip.avi” will create an output file called “myclip.mpg” in the specified directory). If the application encounters a case where the saving of an MPEG file will result in a duplicate name, the original file will be overwritten.

When the conversion is complete, the last of the files to be encoded will be the active file in the Output Video Stream Display, and the option to view the message log is displayed.

A Cancel button is provided to exit Batch Processing mode at anytime. The Joblist will not be lost until you exit the application, allowing you to temporarily exit Batch Processing mode to do other work (for instance, to create a new Profile). You will not be prompted to save changes made to a Joblist, so save it if you expect to use it again.


Achieving Best Results

LSX-MPEG Encoder

To achieve the best results from encoding, the user has to find a set of parameters most adequate to the purposes of a particular task. There is no general rule on how to find the best combination of parameters. The following sections, however, are recommendations based upon experimentation by developers using the LSX-MPEG Encoder. Treat them not as rules, but as helpful guidelines for a variety of encoding situations and needs.

Beginner’s Guide to MPEG Encoding

Achieving Fastest Encoding

Achieving Best Picture Quality

Balancing Quality and Performance

Encoding with Low Bitrates


Beginner's Guide to MPEG Encoding
Beginner’s Guide to MPEG Encoding

LSX-MPEG Encoder

Here are some general guidelines to keep in mind when setting the parameters for your MPEG files:

Know Your Target

Before you begin encoding with LSX-MPEG Encoder, it is important to have some idea of the target audience for your encoded video, and what kind of platform they will have. Having some idea of how (and by whom) your video will be watched will help you make good choices on options like format (MPEG-1 or MPEG-2), bitrate, frame size, and so on. In many cases, you may be your only audience, so you’ll be able to be more flexible with your choices. Other situations may require you to consider not only who will be watching your video, but also what platform they will be using.

For instance, distribution to many people over the Internet means you’ll have to take a number of factors into consideration. How fast is their connection to the Internet (even small video files are big at 28.8k)? Will they be using multiple operating systems, and what kind of media player (software or hardware) will they have? Do they have fast processors, or are there still a few Pentium II 200 MHz users out there?

Resolution (frame size)

In many ways, resolution can be one of the most important choices you make when encoding video, because it will determine what settings are best for other parameters. There is a great temptation to process video at a resolution as high as the system will allow, in the belief that this will result in a better picture.

The resolution of computer video, however, doesn't generally equate to the video world of televisions, VCRs, and camcorders. These devices have standards for resolution that are generally focused on the horizontal resolution (the number of scan lines from top-to-bottom that make up the picture). Here are some numbers for comparison:

Video Format	Horizontal Resolution

Standard VHS	210 Horizontal Lines

Hi8	400 Horizontal Lines

Laserdisc	425 Horizontal Lines

DV	500 Horizontal Lines

DVD	540 Horizontal Lines

With these numbers in mind, it is important to remember this rule when bringing the worlds of computer and video together: the quality of an image will never be better than the quality of the original source material.

We suggest capturing at a resolution that most closely matches the resolution of the video source. For video sources from VHS, Hi8, or Laserdisc, SIF resolution of 352x240 will give good results. For better sources such as a direct broadcast feed, DV, or DVD video, Half D1 resolution of 352x480 is fine. There are other advantages to following these guidelines. Your files will be smaller, consuming less space on the hard drive or on recordable media like CD-R and DVD-RAM. You'll also be able to encode more quickly.

Format - MPEG-1 or MPEG-2?

Although you can choose format according to the resolution you choose (as outlined in the performance table above), the most important factor is the purpose of your video. MPEG-1 is supported on many more desktops at this time than MPEG-2. Although software and hardware DVD players are technically MPEG-2 players, the reality is that many of them are tuned specifically for DVD and not the broader category of "all MPEG-2". If you are encoding video for personal use on your MPEG-2 enabled system, and targeting high-quality, larger resolution video, MPEG-2 is a good choice. If you are working with smaller resolutions, or plan on distributing your project to a wide variety of viewers, you may want to choose MPEG-1. Although MPEG-1 is often associated with low quality video at 1.5 Mbps for older CD-ROMs, you can still set the bitrate and quality settings twice as high to get video that looks very impressive.

Video Data Rate

The video data rate setting determines the quality of your video and the resulting file size more than any other setting. The larger the allotted bitrate, the more information the encoder can use for the video information. Here is a table with some suggested target data rates, depending on what you're trying to accomplish:

QUALITY RATING	RESOLUTION	SUGGESTED

DVD Quality	720x480	5000 Kbps

High Quality	640x480	4000 Kbps

Television Quality	352x480	3000 Kbps

VideoCD Quality	352x240	1500 Kbps

Internet Quality	176x140	500 Kbps

LSX-MPEG Encoder has two distinct modes for controlling video data rate: Constant Bitrate (CBR) and Variable Bitrate (VBR). It is recommended that you reserve use of VBR for MPEG-2 files, as some MPEG-1 players are capable of playing only CBR MPEG-1 files.

As the name suggests, CBR encodes video at a fairly consistent data rate throughout the encoding process, regardless of the amount of information or motion within the video. The encoder will attempt to match the average data rate to the assigned data rate as close as possible. There is always some minimum limit of data rate depending on input frame sizes, frame rate, and characteristics of a particular video file.

VBR mode can produce better picture quality than CBR mode for the same output file size, or a smaller file size for the same image quality. It is achieved by dynamically allocating more bits for the complex pictures or faster moving images, and less bits for simple or slow moving images. The VBR mode also uses a process called quantization to smooth variations and prevent low quality frames in highly active video sequences, which is almost unavoidable when using CBR.

Whether using CBR or VBR, the values in the table above still apply. In CBR mode, simply use the value (or a value near it) for the video data rate. In VBR mode, the value will help you choose three settings. Maximum bitrate is the absolute peak bitrate that the encoder cannot exceed, no matter how complex the video. Average minimum bitrate is the average value that you want the encoder to use when dealing with simple or slow moving segments of video. Average maximum bitrate is the average value that you want the encoder to use when dealing with complex or fast moving sequences of video.

For example, suppose you are encoding a sequence of high quality video at 640x480. In CBR mode, you may wish to assign a video data rate around 4 Mbps. In VBR mode, you might set the absolute maximum bitrate to 8 Mbits (for really complex scenes), average minimum bitrate around 2 Mbps (for slower material), and average maximum around 4 Mbps (for more complex material). Depending on the video source, you could actually end up with a slightly smaller, better-looking file with VBR than with CBR.

VBR mode also has a setting for quantization that can affect the quality and size of the video output. Try to keep the setting between 1 and 3 for best results, as this limits the encoding of extreme (often imperceptible) frequencies.

Audio Data Rate

This setting controls the bitrate assigned to audio, which in turn affects the quality of the audio output. In most cases, a bitrate of 64 Kbps for Mono audio or 128 Kbps for Stereo will be sufficient. If smaller file sizes are important, adjust the bitrate down to 32 Kbps for Mono audio or 64 Kbps for Stereo.

Performance (Motion Estimation)

Along with video data rate, the Performance setting in LSX-MPEG Encoder has the greatest effect on the quality of the video output. The quality setting equates to how much of your processor resources are given to the Motion Estimation algorithm during encoding. Slow modes of motion estimation should generally provide better quality. The results can be simply defined as follows:

- “Very fast” encoding, low quality, lowest processor utilization

- "Fast" encoding, normal quality, low processor utilization

- "Normal" encoding, high quality, default processor utilization

- "Slow" encoding, very high quality, more processor utilization

- "Very Slow" encoding, maximum quality, maximum processor utilization

The rating you choose will depend how much time you have to encode, what processor you are using, and what frame size you are recording.

Sequence

With LSX-MPEG Encoder, you can set the amount of P and B frames in the output. The user can change the number of P frames between the nearest I frames, and the number of B frames between the nearest P frames. ). The default sequence of one I frame followed by 3 P frames and 2 B frames (I BB P BB P BB P BB,  I ...) is suitable in most cases. There may also be two additional options: I frames only (no P or B frames), and I and P frames only (no B frames).

Keep in mind that an MPEG file having only I frames or only I and P frames will be much larger than files taking advantage of the full IPB structure. The optimum value for the number of B frames is "2" or "3". If you want to achieve the better quality at the expense of data rate, you may want to increase the amount of P frames to some value between "6" and "10". If these suggestions are still not providing the desired results, you may want to try adjusting the video data rate instead or increasing the motion estimation quality settings.

Many other parameters can also be specified, but these are the major ones. See the section Advanced parameters dialog box to learn how to enter the required parameters in the LSX-MPEG Encoder program.


Achieving Fastest Encoding

LSX-MPEG Encoder

This section provides some recommendations on how to encode an MPEG file as fast as possible (but with acceptable quality) with the LSX-MPEG Encoder. There is no universal recommendation for the best choice of all these parameters as speed varies according to source video, processor speed, etc.. Test different MPEG encoding settings until the fastest encoding is obtained. The following choices of parameters are suggested (in some cases the possible range of parameters is shown).

Maximum motion vectors

P frame maximum horizontal motion vector	16, 24, 32

P frame maximum vertical motion vector	8, 16

B frame maximum horizontal motion vector	8, 16, 24

B frame maximum vertical motion vector	8, 16

Frames

In most cases, the default sequence (3 P frames between I frames and 2 B frames between P frames) provides suitably fast encoding.

If you want faster encoding, reduce the amount of B frames as the encoding of B frames takes more time than P frames. Set one B frame between P frames.

Performance mode

Set "Fast" or "Very fast" performance mode. Tests show that even in "Very fast” mode, quality is often close to the best possible quality achieved in slow modes of operation. There is usually no significant subjective difference in image quality between files created in fast and slow modes of encoding. However, it may depend on a particular input video stream and other conditions of encoding.

Preprocessing Filters

The filters of the Input Property Page  (Low Pass, Median Pass, Deinterlace, and Detect Inverse Telecine) always require more processing when turned on. If speed is a primary consideration, turn one or more of them off.

Picture options

Drawing of input and output frames takes significant time during encoding, especially computers with slower processors. This application has been optimized for true color modes (24 bit pixel values), use of other color modes may affect the speed and picture quality.

If you want faster encoding, disable drawing input and output frames. By default, the program displays the output video stream. You will find that disabling one or both of these can often give you an increase in the speed of encoding by up to 10 to 20%. The only disadvantage is that you will not be able to visually study the process during encoding.

You can also disable calculation of image quality because it also consumes processor time during encoding.


Achieving Best Picture Quality

LSX-MPEG Encoder

This section provides some recommendations on how to encode an MPEG file with the best possible picture quality. The following choice of parameters is suggested (in some cases a possible range of parameters is shown).

The video stream data rate is one of the main parameters affecting the output picture quality. So if picture quality is not satisfactory, increase the data rate, if it is acceptable for the particular application. The picture quality also depends on such encoding parameters as maximum motion vector values, frame sequence and performance mode. If the video stream data rate is limited and you cannot increase it, try to adjust other parameters.

There is no universal recommendation for the best choice of all these parameters. Test different MPEG encoding settings until the best possible image quality is obtained.

Maximum motion vectors

Optimum values of motion vectors depend upon the statistics of a particular input video file.

Here is a possible range of maximum motion vector values. To achieve the best results, the user may need to encode with different values of maximum motion vectors.

P frame maximum horizontal motion vector	16, 24, 32, 40

P frame maximum vertical motion vector	16, 24, 32

B frame maximum horizontal motion vector	16, 24

B frame maximum vertical motion vector	16, 24

Frames

Since encoded I frames are much larger than P and B frames and P frames are larger than B frames, you should increase the amount of P frames between I frames. Usually 3 or 5 P frames between I frames give good results if the data rate is limited. The optimum number of B frames is usually 2 or 3. If a very low data rate (8 Kbits/sec or less) is required, then sometimes another choice of sequence parameters may help to achieve better results: One B frame between P frames and one P frame between I frames.

Select this link to see more about Encoding with Low Bitrates.

Performance mode

As was already mentioned in the section about performance parameters, theoretically, slow mode must provide better motion estimation and result in better quality. In practice, however, it is not always true. In some cases "slow" and "very slow" modes do not provide a significant gain in quality. It depends on the content of a particular input video file. Try "Normal speed" and "Slow" modes.

Preprocessing Filters

Enabling prefiltering (via the Input tab of Advanced Parameters can improve picture quality by reducing visual “noise” in the stream.

The Low Pass filter removes high frequency components of the picture. It reduces noise, but also removes small image details and makes image look less sharp. The Median filter usually helps to reduce random noise without removing small details or reducing sharpness of picture. It works by sorting values of all pixels near the specified pixel and selecting the median value. The numerical value from 1 to 100 can be specified for the Low Pass and Median filtering. This value determines the "level" of filtering. Choosing a larger value results in better noise reduction, but may also result in reducing image sharpness. Experiment with these numbers against specific input files until you achieve the desired result.

Deinterlace should be enabled whenever transcoding fullscreen video. Such video source is often captured as interlaced video, which exhibits jagged lines when played back on a computer monitor.  The problem of these “jaggies” appears because odd and even scanlines of the captured picture originated on different video fields of interlaced source video signal. The Deinterlace functions of LSX-MPEG Encoder allow the user to create better quality progressive video from the interlaced by interpolating odd scan lines using the pair of nearest even scan lines.

Bitrate options

Proper use of variable bitrate mode can produce much better quality MPEG-2 video than the same size video encoded at constant bitrate. VBR mode gives the encoder flexibility to dynamically allocate more bits for complex scenes, avoiding “patches” of low quality video in highly active sequences.

Each of the three VBV (buffer verifier) buffer modes requires the user to enter a value for Maximum bitrate, the absolute peak limit of the bitrate. It is recommended that the value be no more than the maximum bitrate associated with the appropriate target platform, or MPEG-2 level and profile. For full screen video, we have had excellent results in the 8000 to 9000 Kbits/sec range. Once this value is set, you must choose which of the VBV modes you will use:

-	Simple VBR mode requires only one additional value, that of Average bitrate. This value will probably be similar to what bitrate you might select in Constant Bitrate mode. For full screen video, we’ve had good results in the 3000 to 4000 Kbits/sec range.

-	Constant quantization mode does not allow you to specify an average bitrate, but rather requires a value for quantization. Lower settings here equate to less noise and fewer extreme video frequencies being encoded, and therefore better quality video. This is a somewhat experimental process, as it can result in large video files (controlled only by the Maximum bitrate setting above) and longer encoding times, but quality results are almost guaranteed. This mode is a good one to use if file size and encoding time are not your primary concern. The quantization scale can be summarized as:

-	1 – 3: very good image quality

-	4 – 5: good image quality

-	6 – 8: medium image quality

-	9 – 11: low image quality

-	11 – 31: very low image quality, suggested only for low data rates

-	Optimized quantization scale mode allows you to choose both the quantization value, as well as set Average Maximum and Average Minimum values for the bitrate. Select quantization on the basis of the quality you’re trying to achieve. We have had excellent quality results with quantization set to “1”, Average Maximum set to ½ of the Maximum Bit rate (for full screen, around 4000 Kbits/sec), and Average Minimum around ½ of the Average Maximum (for full screen, around 2000 Kbits/sec).


Balancing Quality and Performance

LSX-MPEG Encoder

This section provides some recommendations on how to encode MPEG files achieving optimum balance between picture quality and performance requirements.

Maximum motion vectors

P frame maximum horizontal motion vector	16, 24, 32

P frame maximum vertical motion vector	16, 24

B frame maximum horizontal motion vector	8, 16, 24

B frame maximum vertical motion vector	8, 16

Frames

In most cases the default sequence of 3 P frames between I frames and 2 B frames between P frames gives fast encoding.

If you want faster encoding then reduce the amount of B frames, because encoding B frames takes more time than encoding P frames. Set 1 B frame between P frames.

Performance mode

Set "Normal speed" performance mode. Tests show that "Normal" mode quality is often very close to the best possible quality achieved in "Very slow" mode of operation. However, it may depend on a particular input video stream and other conditions of encoding.

Picture options

Drawing of both input and output frames takes significant time during encoding, especially computers with slower processors. If you want to achieve faster encoding while still analyzing your video, disable the drawing of input frames. By default, the program displays the output video stream. You will find that disabling one or both of these can often give you an increase in the speed of encoding by up to 10 to 20%.

Bitrate options

In VBR mode, performance is generally determined by changes made to the quantization value. As shown in the section on Achieving Better Picture Quality, a lower quantization value equates to better quality, but it also results in larger files and larger consumption of processor resources. To summarize:

-	1 – 3: very good image quality, highest data rate, slower encoding

-	4 – 8: good or medium image quality, medium data rate, medium encoding speed

-	9 – 11: low image quality, low data rates, fast encoding

-	11 – 31: very low image quality, very low data rates, fastest encoding


Encoding with Low Bitrates

LSX-MPEG Encoder

A special set of skip frame modes in the LSX-MPEG Encoder is designed to help create MPEG files with very low data rates.

The MPEG standard specifies the following frame rates: 23.976, 24, 25, 29.97, 30, 50, 59.94, and 60 frames/sec. There is no provision in the standard for support of frame rates lower than 23.976 frames/sec.

It is usually not possible to transmit a video sequence with a high frame rate and a high image quality with very low data rates suitable for modem communication over telephone lines and other applications. It is, however, often acceptable to sacrifice visible frame rate, but keep better visible picture quality.

There is a way to reduce apparent frame rate by creating a special "skipped" frame, which is essentially a B frame with no picture change information. When a standard MPEG player plays a file with skipped frames, these frames repeat the picture of the nearest P frame.

The use of skipped frames allows the encoder to allocate more bits of data for encoding of other non-skipped frames improving the visible picture quality. The more skipped frames allocated in the frame sequence the better the visible quality of the remaining non-skipped frames will be. The maximum possible allocation of skipped frames is achieved by selecting the "Skip all B frames" option in the Special property page of the Advanced dialog window.

To increase the amount of skipped frames in this mode make the total amount of B frames larger in frame sequence settings. Do not make the amount of B frames too large because the effective visible frame rate may drop below the acceptable value. Also, try to keep some reasonable correspondence between the visible frame rate and visible picture quality for a particular video source and required data rate.

For example, selecting the "Skip all B frames" option, when the frame rate is 25 frames/sec, with  5 B frames and 3 P frames in the sequence, will effectively result in a visible frame rate of 5 frames/sec. This may be sufficient for some low data rate applications (and is a common frame rate for, say, streaming video over a 28.8 connection to the Internet).

In some special video applications, like multimedia presentations or training materials it could be acceptable to reduce the visible frame rate even more. The program allows a maximum of 30 B frames in the sequence. A special video application used in combination with the special "Skip all B frames" mode could theoretically allow the user to have a visible frame rate less than 1 frame/sec.

The ability to skip B frames is very useful when used in conjunction with the Sequence tab. For more information on how to change frame sequencing in order to achieve faster encoding, smaller file size, and higher quality, see the sections on skipping B frames in Advanced User Questions.

NOTE: The use of skipped frame modes is consistent with the MPEG encoding standards. A standard MPEG player should play these files correctly, but some MPEG video players may fail to decompress files with skipped frames. This is a limitation of the particular MPEG video player.

Other measures that can be used to obtain a very low data rate, but still keep acceptable picture quality are applying the best-suited combination of:

-	maximum motion vector values

-	frame sequence settings

-	program performance settings

-	filtering options

Usually shorter maximum Motion Vector values should be selected for small frame sizes and/or little motion in the image. A general rule is to increase motion vectors for the video with fast motion, or reduce motion vectors for the video with less motion.

Increasing the amount of P and B frames in the Sequence tab in a subgroup may help to improve the picture quality in a low data rate file.

Reducing the encoding speed to "Slow" or "Very Slow" in the Performance tab modes may improve picture quality, depending on the input file.

Finally, use of the Median or Low Pass prefilters in the Input tab may reduce unwanted noise in low bitrate or small frame images. The numeric value of the filter (1..100) is a representation of the frequency range being scanned. Just keep in mind that the use of filters will slow down the encoding process.


Frequently Asked Questions

LSX-MPEG Encoder

General Encoder Questions

New User Questions

Advanced User Questions

Error and Warning Messages


General Encoder Questions

LSX-MPEG Encoder

What is LSX-MPEG Encoder?

The LSX-MPEG Encoder is an application that allows you to transcode AVI format video files to MPEG files.

What are the advantages of the LSX-MPEG Encoder program over other software MPEG encoders?

The unique features of LSX-MPEG Encoder are:

1. Intel MMXTM processor support for maximum speed of MPEG video encoding.

2. The revolutionary LightSpeed motion estimation algorithm for fastest encoding of MPEG in software available. Due to this new algorithm, the LSX-MPEG Encoder works several times faster than any other software MPEG encoding programs, while still providing virtually the best possible compression and image quality.

3. A simple, flexible interface that is easy for new users, but still allows experienced users control over a number of advanced MPEG encoding parameters. The Batch Processing and Profile Manager features not only make the encoding process easier, but also automate tasks to make you more productive.

4. A special mode for creating very low data rate MPEG video files, which makes the program great for creating MPEG files for Internet applications.

5. A new single-pass Variable Bitrate that can produce better picture quality than Constant Bitrate mode in the same file size, or a smaller file with the same image quality

6. Multiplexed output of MPEG-1, VideoCD and MPEG-2 formats.

What video compression formats in the input AVI video files are supported?

The LSX-MPEG Encoder reads input AVI files with almost any kind of video compression, including Indeo, Cinepak, Intel Video Interactive 4.1, Power! Video, Fractal FIF by Iterated Systems, Intel Video Raw (uncompressed YUV), YUV9, most M-JPEG codecs, uncompressed RGB with 8, 16, 24, and 32 bit/pixel, and many others. The program will accept video frames from almost any AVI file if your system has an appropriate video codec installed and can play that AVI file. If the program can’t read the video stream from the AVI file, then you need to install an appropriate Video for Windows video codec.

What audio compression formats in the input AVI video files are supported?

The LSX-MPEG Encoder reads audio streams from input AVI files with uncompressed PCM audio format, 8 or 16 bits/sample, mono or stereo, and sample frequency 48000, 44100, 22050 or 11025 Hz. This covers most audio formats used in AVI files. If the LSX-MPEG Encoder cannot accept an audio compression format, it is still able to compress the video stream. If the program cannot accept an audio compression format and audio compression is required, the AVI file audio format can be easily changed to one of the standard acceptable audio formats by using any second party video-editing program. Note that at this time, LSX-MPEG Encoder does not support conversion between Mono and the three Stereo modes (though the data rate may still be adjusted).

What output files can it create?

The LSX-MPEG-Encoder can create multiplexed video and audio MPEG-1 and MPEG-2 streams. LSX-MPEG Encoder also supports creation of “White Book”-compliant VideoCD MPEG-1 streams. It can also create MPEG-1 Level II audio stream files by changing the settings in the Files tab in the Advanced Parameters dialog to retain the temporary audio files.

Who should use the LSX-MPEG Encoder?

Anyone who wants to create MPEG files on a personal computer without investing in expensive hardware encoding solutions. It is the fastest and most flexible software MPEG encoder available today. On PCs with an Intel MMXtm processor, this program works as fast as some hardware MPEG encoding boards at a fraction of their cost.

Applications of the LSX-MPEG encoder are:

1. Creation of multimedia CD and DVD production, improving the appearance of games, presentations, kiosks, and educational titles.

2. Creation of libraries and databases of digitized video clips.

3. Delivery of highly compressed, cross platform video files for Internet applications such as video e-mail, online catalogs, training and promotional material, or movie trailers. The LSX-MPEG Encoder has unique modes for creating bandwidth-friendly files with high-quality and very low data rates.

4. Reduce disk space occupied by larger AVI video files, and even produce VideoCDs that can be played back on computers or most DVD players.

5. Study the fundamentals of digital video compression without the expense of a hardware-based system.

6. Creation of high-quality video assets for DVD-Video production.

What is the difference between MPEG-1 and MPEG-2?

MPEG-1 and MPEG-2 are international standards for encoding digital video information. They are created by the Moving Picture Coding Experts Group (MPEG) of the Joint ISO/IEC Technical Committee (JTC 1) on Information Technology. MPEG-1 is formally known as ISO/IEC 11172 and MPEG-2 is formally known as ISO/IEC 13818.

MPEG-1 is suitable for low and medium data rate applications producing image quality comparable to VHS tape. Such applications include computer multimedia CD-ROM titles, computer games, video training materials, video databases, and networked video applications. It is generally used for video of resolutions up to 352x288 and data rates up to 2 Mbits/sec.

MPEG-2 is designed for higher quality video applications like DVD, video on demand, and digital broadcasting. It is generally used for resolutions and data rates greater than those listed above for MPEG-1.

What are the advantages of storing digitized video in MPEG format over the other known video compression file formats like AVI and QuickTime?

MPEG-1 and MPEG-2 are international standards. The MPEG files are operating system independent, unlike formats such as AVI and QuickTime. MPEG-1 playback is now standard on most systems sold today. With the proliferation of DVD players on PCs, the same is happening with MPEG-2. In most cases, MPEG provides better quality video in a smaller file size than AVI or QuickTime codecs. In the past few years, it has become very easy to capture analog input video as an AVI file with an inexpensive video capturing card on a PC, optionally edit the AVI video file, and then convert the AVI file to MPEG using our LSX-MPEG Encoder.

How does the LSX-MPEG Encoder change the process of creating MPEG files?

Until recently, creating MPEG files was not very practical for anything except high-end applications. MPEG required expensive hardware for capture, editing and playback. The first software MPEG encoders were very slow at converting input video files to MPEG at speeds of less that one frame per second. The situation has now changed due to the introduction of newer and faster processors in personal computers. These faster systems, along with our new LSX-MPEG Encoder, allow you to create MPEG video files at the same speed of some hardware encoders for a fraction of the cost. By using the LSX-MPEG Encoder on processors with MMX technology, maximum video encoding speed can be obtained.

What is MMX and what does it do for MPEG encoding?

MMX is the media enhancement technology introduced in Intel's Pentium II line of processors. The instruction set of Intel's processors is extended by 57 powerful instructions specifically designed for manipulating and processing video, audio, and graphical data more efficiently. These instruction sets are oriented to the parallel, repetitive sequences often found in multimedia operations. The MMX instructions can operate simultaneously, improving the speed of many multimedia applications by several times.

LSX-MPEG Encoder is specifically designed to fully take advantage of this new technology, and was one of the first applications for digital video production that fully utilized MMX technology. When the application is started, it automatically recognizes if the processor has MMX support and uses the MMX instructions for the maximum encoding speed of MPEG video streams.

What speed gain is obtained by using MMX technology with the LSX-MPEG Encoder?

According to our tests, using MMX technology increases speed 2 to 3 times faster for MPEG video compression.

Can users without MMX processors use the LSX-MPEG Encoder?

The LSX-MPEG Encoder program does not require an MMX processor. If the computer has MMX capability, the program will recognize and use it. The output MPEG file will be exactly the same, with or without MMX processor support. The only difference will be in the speed of encoding. Even without MMX technology, the LSX-MPEG Encoder compresses video streams faster than other software MPEG encoders.

Can I turn off the MMX instruction support when running the LSX-MPEG Encoder?

Yes. The MMX instructions within the LSX-MPEG Encoder can be turned off by adding to the command line of the LSX-MPEG Encoders' execution command line the following /notmmx, which will tell the LSX-MPEG Encoder to not use the MMX instructions during the encoding of your files.


New User Questions

LSX-MPEG Encoder

I used to use LSX-MPEG Encoder with my monitor set at 640x480. I installed LSX-MPEG Encoder 3.0, but cannot open the application anymore.

This latest version of LSX-MPEG Encoder requires your display screen area setting to be 800x600, minimum. If you are running at a lower resolution, or with large fonts enabled, you’ll need to change your display settings when using LSX-MPEG Encoder.

I upgraded from a previous version of LSX-MPEG Encoder, and used to see two video windows (Input Video Stream and Output MPEG Video Stream). Now when I open, I only have one viewing window for the video while encoding. What happened?

In LSX-MPEG Encoder 3.0, the default setting is for display of video output only while encoding (this can be changed).  This is less confusing than the previous interface, and eliminates the problems associated when encoding larger frame sizes on small screens. In addition, fewer processing resources are required to display only the Output MPEG Video Stream, resulting in slightly faster encoding. To re-enable the display of Input Stream video, enable “Show input stream frames” in the View Menu. If you want the change to be permanent, select “Save current settings as Default”. Until encoding actually begins, the windows will display the LSX-MPEG logo.

There are many complicated options in the "Advanced" dialog box. Do I need to specify all of these parameters before I start encoding an MPEG file?

No. When the program is started and a new input AVI file is selected, the program will set all advanced parameters by predetermined default values. These values are acceptable in most cases and produce highly compatible MPEG files. In the main dialog window, just set the format (MPEG-1 or MPEG-2), audio, frame rate and data rate options.

LSX-MPEG Encoder comes with a number of common, predefined Profiles that can be applied to any input source file. Once loaded via the Profile Manager, these Profiles can be easily used or customized. Descriptive names such as “MPEG-1 VideoCD NTSC” and “MPEG-2 Main Profile @ Low Level” will help you select the proper Profile for your intended application of the encoded file.

I created an MPEG video file. How can I play it?

The Preview function of LSX-MPEG Encoder brings up Active Movie or the Windows Media Player (depending on which is on your system), and will playback the file. MPEG-1 decoding and playback is handled by the default Windows MPEG-1 decoder. For MPEG-2, LSX-MPEG Encoder now includes the LSX Player, a software filter that provides quality playback of MPEG-2 video directly through Microsoft's Windows Media Player.

I don’t use Active Movie or Windows Media Player for my MPEG playback. What should I do if I created an MPEG file using the LSX-MPEG Encoder and it does not play on my favorite MPEG player?

Although the output MPEG files created by the LSX-MPEG Encoder are compliant with MPEG standard specifications, most MPEG players can only play MPEG files that are within a limited subset of encoding parameters. Many free software and low-cost hardware MPEG players play only MPEG-1 files that meet the MPEG-1 specification of Constrained Parameters. It is a good idea to create MPEG-1 files that are compliant with Constrained Parameters whenever possible. In the case of MPEG-2, some PC DVD players can playback MPEG-2 streams, but not all. Although DVD video is a subset of MPEG-2, many players were only designed to decode the narrow parameters of DVD, not all MPEG-2 files. See the particular MPEG player documentation for more information. If changing encoding parameters does not help, you may need to choose another MPEG player.

I have the opposite problem! I have a DVD, and the LSX Player will not play it!

LSX Player is not a software DVD player. There is more to DVD-Video than just MPEG-2 video, and LSX Player is not designed to decode DVD “vob” files, AC-3 audio, DVD menus, etc.. It is simply an MPEG-2 software decoder than can play MPEG-2 files produced by LSX-MPEG Encoder and other MPEG-2 encoders. You will need to use the DVD decoder supplied with your DVD drive, or obtain an application specifically for DVD playback.

What should I do if I created an MPEG file using the LSX-MPEG Encoder and the picture quality is not good enough?

The LSX-MPEG Encoder allows you to set many different encoding parameters that affect picture quality. The most significant parameter is the video stream data rate. Increase the data rate if it is suitable for your application. You may want to slow the speed of encoding to allow a more extensive search for Motion Estimation. You may also want to try encoding in Variable Bitrate mode and setting the quantization value lower to produce higher quality. As there are a number of factors that affect quality, be sure to see the section on Achieving Best Picture Quality.

It is also possible that your MPEG player caused the low picture quality during playback.  Some MPEG players allow you to set playback quality options depending on the system capabilities.

What should I do if I created an MPEG file using the LSX-MPEG Encoder and the quality of the audio is not good enough?

The LSX-MPEG Encoder allows you to set several audio encoding parameters that affect sound quality. These parameters are selected from the Audio property page in the Advanced dialog window. The most significant parameter is the audio stream data rate. The default audio data rate is 64 Kbits/sec for mono and 128 Kbits/sec for stereo sound. The maximum available audio data rate is 192 Kbits/sec for mono and 384 Kbits/sec for stereo sound. If the input AVI file has a mono audio stream, then the output MPEG file also has mono audio. If the input file has a stereo audio stream, then the output MPEG file may have one of 3 possible encoding modes; stereo, dual, or joint stereo mode. The stereo mode is preferable for best sound quality with high data rates. The joint stereo mode may improve sound quality on low data rates.

It is also possible that your MPEG player caused the low audio decoding quality during playback. Some MPEG players allow you to set the audio quality options depending on the system capabilities. Usually software MPEG players use low audio decoding quality options by default. If you have a fast system (a Pentium II processor or higher), then you may be able to set a higher quality audio decoding option for your player.

I want to transcode long AVI clips (about 18 minutes or 1 gigabyte) but when I try it doesn't work.

This is a limitation of the Video for Windows software and the AVI file format itself. The LSX MPEG Encoder uses Video for Windows to decode the input file while encoding and it has a limitation of 1 GB. Recent versions of Microsoft’s DirectShow remedy this a bit, raising the limit to 2 GB. You may also use special hardware or software from third-party vendors that allows larger AVI files. As long as your system can decode these files in Active Movie or Windows Media Player, LSX-MPEG Encoder should be able to work with that file. The 1 and 2 GB limits do not apply to the MPEG files you create. For more information on the AVI file format and how to get around the file size limit, see our MPEG Resources page.

I want to encode full screen PAL MPEG-2 video but LSX-MPEG Encoder gives me an error that the horizontal size is greater than permitted in the specified level.

The pixel rate for PAL Main Profile at Main Level MPEG-2 (MP@ML) is specified as a maximum frame size of 720x576 at 25 frames per second. Make sure your Frames/Second in the Main Window is set to 24 or 25 fps, and that your Source Video Format in the MPEG-2 tab is set to PAL.

How can I crop or rescale the frame size (in pixels) of my video clip?

Since LSX-MPEG Encoder is not a video editor, you will need to change the input AVI file before you load it for encoding. Most video editors will allow you to adjust the resolution of the clip.

I tried to encode a number of files using the Batch Processing feature, but they all came out too short with the wrong number of frames.

You must change Frames to Encode to a value of “1” and save it in the current Profile before entering Batch mode. This is equivalent to setting the number of frames to “all”. Since all the files you encode will probably be of different lengths (in terms of frames and time), it is important to reset this so the Encoder knows to encode the entire length of all the files in the Joblist.

What should I do if the input file frame rate is different from any of the output MPEG file frame rates listed in the main program window?

The MPEG standard specifies the following frame rates: 23.976, 24, 25, 29.97, 30, 50, 59.94, and 60 frames/sec. There is no support for other frame rates. Currently, the LSX-MPEG Encoder supports the following frame rates 23.976, 24, 25, 29.97, and 30 frames/sec. If your input AVI file has one of the frame rates in this list, then just set the same frame rate for the output MPEG file. If the input AVI file does not have one of the frame rates in the list, you will need to create an MPEG file with a different frame rate. The frame rate conversion procedure will be applied as described below.

The LSX-MPEG Encoder has two different modes of frame rate conversion to encode files with frame rates different from the frame rates in the input file. The first option is to keep the original playback time the same as the input file. This is the default mode and is the only available option when encoding video and audio. In this mode, the program may duplicate or skip some input video frames to ensure proper synchronization. The second option is to keep the original frame sequence. In this case the playback time and speed of the output MPEG file will be different from the original. Both of these options are available when compressing video streams without audio. This option can be selected from the "Sync" property dialog window in the "Advanced" dialog box. When the user opens a "new" AVI file and the new file has an audio stream, the default option is selected automatically.

I am encoding an MPEG file and often change the video (audio) encoding or multiplexing parameters without changing the audio (video) parameters.  Can I skip a step in the video (audio) stream encoding every time?

Yes. The LSX-MPEG Encoder creates MPEG streams in 3 steps: 1) Encodes the video stream to a temporary file, 2) Encodes the audio stream to a temporary file, and 3) Multiplexes the video and audio into a system stream in the output file. The program allows you to skip the first and/or second step of encoding if the video or audio stream file already exists. To use this option with an existing video (audio) stream file, the temporary file name in the "Files" property page must be the same as the existing file. If you do not want the temporary file with the video or audio stream to be deleted after the encoding (default mode), then disable this option in the ‘Files" property page. When encoding with the existing audio or video stream temporary file, answer "No" on the warning message to skip the encoding of this video (audio) stream and use the existing file. Note: You may set the temporary file name to any filename.

I am encoding an MPEG file and the number of frames in the output file is different from the number of input video frames. Why?

The number of output video frames will be different from the number of input video frames if the frame rate in the output MPEG file is different from the input frame rate. In the default encoding mode ("keep original duration"), the program may duplicate or skip some input frames to ensure proper playback time and audio synchronization. If only the video stream is compressed (no audio), then you may choose the other mode ("keep original number of frames") in the "Sync" property page of the "Advanced" dialog window.

I encoded an MPEG file using LSX-MPEG Encoder and the output file size is larger than the input AVI file size. Why?

The size of the output file depends on the specified data rate. To reduce the size of the output file, simply reduce the specified video and audio stream data rate. The video stream data rate is specified in the main program window (in the amount of Kbits/sec), and the audio stream data rate is specified in the "Audio" property page of the "Advanced" dialog window (in the amount of Kbits/sec). The data rate is the main parameter affecting the output picture quality. If the selected data rate is too low for a particular video file, the picture quality may be reduced. If you need to create very small MPEG files (for Internet applications, for instance), see the section Encoding with Low Bitrates.

I see only a fraction of the input and output video frames in the program window during the video encoding. Can the program scale the images up or down to the maximum extent of the window area?

The program has 2 modes of picture drawing; with or without scale. The default mode is to draw pictures without scale. In this mode, the program shows the largest image area possible. If the picture is larger than the window area, the program will crop the central portion of the image area. The program does not scroll (move) pictures inside the window. To be able to see the entire picture, enlarge the main program window.

The second drawing mode is to scale images up or down to the maximum extent of the image window. The program will try to keep the aspect ratio of the original picture. To set this mode, click on the item "Scale images to window" or simply press "ALT+W". A checkmark will appear beside the menu item to show that the scaling mode is activated. This mode may be useful when compressing files with very large image sizes to see the whole image area or when compressing files with very small image sizes to enlarge the small details on the picture. The disadvantage of using the scaling mode is that it may significantly reduce program performance due to the extra time required for image scaling operations.

What is the definition of compression ratio that the program reports for input and output files?

When reporting the input AVI file properties, the program calculates compression ratio as a ratio between the estimated size of an uncompressed 24 bit/pixel RGB frame, multiplied by the number of input frames and the actual size of video stream data in the AVI file. The input file compression ratio calculated this way may be approximate, and is provided only for the user’s convenience.

The program calculates output MPEG file compression ratios as a ratio between the estimated size of an uncompressed 24 bit/pixel RGB frame multiplied by the number of input and the actual size of the output MPEG video stream file.

What formula was used for the calculation of picture quality that the program reports?

The quality measure is based on mean square error (MSE) value, measured in YUV 411 color space between input and encoded frames. For the user’s convenience, we scale this value to the intuitive range from 0% to 100% using a nonlinear function. A value of 100% corresponds to the maximum possible quality, i.e. MSE=0. This quality measure does not relate to any standard and is provided for the user’s convenience.

What are the *.prf files in the Profile sub-directory?

The profile file (*.prf) is a convenient way to store MPEG encoding parameters for particular applications (such as Video frame rate, data rate, output file format, etc.). These files are used to save and retrieve frequently used sets of parameters. For the most part, though, these files are hidden from the user, but are represented by the individual Profiles in the Profile Manager. If you were a user of earlier versions of the LSX-MPEG Encoder, you had to manage these *.prf files manually. If you have a number of older profile files you wish to use in LSX-MPEG Encoder, you can use the File/Import profile file function on the pulldown menu to add them to the Profile Manager, or copy them into this directory.


Advanced User Questions

LSX-MPEG Encoder

What are the Skip B Frames modes, and when should I use one?

A special set of “Skip frame” modes is available with the LSX-MPEG Encoder in the Advanced Parameters section, under the Special tab. These are designed to help create MPEG files with low data and frame rates. Using skip frames may also help to increase picture quality of the output MPEG file when the input AVI file has a frame rate lower than any of the standard MPEG frame rates.

In digital video, AVI files may have a frame rate that does not match any of the available MPEG frame rates (for instance, 10 fps, 12, fps, 15, fps, etc.). The MPEG standard specifies the following frame rates: 23.976, 24, 25, 29.97, 30, 50, 59.94, and 60 frames/sec. There is no provision in the standard for support of frame rates lower than 23.976 frames/sec.

The LSX-MPEG Encoder program can create MPEG files with frame rates: 23.976, 24, 25, 29.97 and 30 fps. Because many AVI files have frame rates lower than these, many of the input frames will be duplicated to obtain one of the standard MPEG frame rates. The special Skip B Frames modes of LSX-MPEG Encoder eliminate these duplicated frames, and reduce the data rate and apparent frame rate in the process.

There are four options in the Special property page to control skipped frames: "Normal mode, no skipping frames" (default), "Skip 1 B frame", "Skip 2 B frames", and "Skip all B frames”. Other options specify how many B frames in a subgroup sequence will be skipped.

The “skipped” B frame is essentially a frame with no picture change information. LSX-MPEG Encoder does this by skipping most of the macroblock data on the specified frame. For example, when the input format is 640x480, the application codes only 60 bytes for an MPEG-1 skipped B frame, and about 288 bytes for a skipped MPEG-2 B frame. When decoded by a standard MPEG player, the skipped B frames will repeat the picture from the nearest P frame in the sequence.

The effect of using skipped frames depends on the specified sequence settings.

Skip B Frames Example:

An AVI file has a frame rate equal to 12 fps, so it’s logical to encode the output MPEG file as 24 fps, a low value and a multiple of 12. Unfortunately, each of the 12 frames in the input file will be duplicated to make 24 frames.

With a Skip B frames mode, there is no reason to encode information for duplicated frames. We can first reset the frame sequence in the Sequence page of Advanced parameters to easily fit into the 24 fps structure. Set “Number of P frames” to 3, and “Number of B frames” to 3, and we get a GOP of 12 frames that looks like this:

(I BBB P BBB P BBB P BBB)

One second, therefore, looks like this:

(I BBB P BBB P BBB P BBB, I BBB P BBB..)

By going into the Special page and setting the encoder to Skip 2 B frames, the new structure will be:

(I _B _ P _B _ P _B _ P _B _, I _B _ P _B _..)

resulting in an apparent frame rate of 12 frames in a second.

It should be noted that, in order to meet the MPEG specification of a valid frame rate, all 24 frames are technically still there. The skipped B frame is essentially a B frame with no picture change information, so skipped frames are essentially encoded as empty. The result is a valid MPEG file that appears to be 12 fps like the source, requires less data than a 24 fps clip, and is smaller than both the AVI and the default MPEG file.

Specifying a sequence with 3 P frames and 1 B frame could also achieve the same apparent frame rate of 12 fps. A second of this sequence would look like this:

(I B P B P B P B, I B P B P B P B, I B P B P B P B..)

Select the option to "Skip 1 B frame" (or any larger skip option), and the sequence becomes:

(I _ P _ P _ P _, I _ P _ P _ P _, I _ P _ P _ P _..)

and you still end up with 12 fps. Compare this with our original 12 fps sequence:

(I _B _ P _B _ P _B _ P _B _, I _B _ P _B _..)

The two files ended up with different GOP structures, and therefore different types of frames representing the same information. The “green” stream has I and P frames only. The “blue” stream will probably be smaller and provide better quality, because it was able to take advantage of smaller B frames.

NOTE: Files with skipped frames are compliant with the MPEG standard specification. Nevertheless, some MPEG players may fail to play MPEG-1 files with skipped frames. If the maximum system compatibility with any player is required, use of skip frames is not recommended.

What is this “VideoCD” I keep hearing about? How is it different from MPEG?

The VideoCD format (also known as "White Book") is a specific type of MPEG-1 file. VideoCD (VCD) itself is a type of player and the CD that contains movies encoded with a specific set of MPEG-1 parameters. They are extremely popular with consumers in Asia, where dedicated VCD players are widespread, and in video kiosks worldwide. They are becoming much more popular in North America because VCDs can now be played in the most recent generation of consumer DVD players. With the proliferation of recordable CD drives on PCs, it is now inexpensive and easy to record your favorite video projects onto CD, and distribute it to anyone with a PC or DVD player for viewing.

The resolution and quality of VCDs are roughly near VHS tape. When viewed on a PC (through a VCD application or an application like Windows Media Player), the quality will probably look very blocky with a great deal of visible artifacting. This is due to the low resolution and bitrate of these files, and the high-resolution display of PC monitors. When viewed on a television monitor, however, you'll find the picture quality nearly as good as VHS video.

Can I make VideoCDs with LSX-MPEG Encoder?

LSX-MPEG Encoder makes VCD compliant MPEG files for use in VideoCDs, but you’ll still require software to format and burn the VCD. Adaptec’s EasyCD Creator and CeQuadrat’s WinOnCD are two popular applications to finish your VCD project.

What is the VideoCD specification?

The specifications of the VideoCD format can be found in the VideoCD Specification Version 2.0 by Phillips Consumer Electronics, and MPEG Standard (ISO/IEC 11172) documents. In summary, they are:

- MPEG-1 system stream (ISO/IEC 11172-1), or video elementary (ISO/IEC 11172-2)

- Maximum bit rate (total) is 1,377,600 bits per second

- Maximum video data rate is generally 1151929.1 bps (depending on audio)

- Video pack size is 2324 bytes

- One of the following three formats:

NTSC - 352x240, 29.97 fps

Film - 352x240, 29.976 fps

PAL - 352x288, 25 fps

- MPEG 1 audio layer II elementary streams (ISO/IEC 11172-3)

Sampling Frequency - 44.1 kHz

Bitrate - 224 Kbits/sec for audio/video track

- 0 to 384 Kbits/sec for segment only

Mode - stereo, dual channel, intensity stereo; mono allowed for segment

Audio pack size is 23304 bytes.

Do I need to make all of these settings in LSX-MPEG Encoder?

LSX-MPEG Encoder includes a "one click" feature to create compliant VideoCD White Book files. With MPEG-1 selected, check off the VideoCD box. In order for the VideoCD option to appear, your input AVI file must match the following requirements of a VideoCD file:

- Frame size must be either 352x240 (NTSC) or 352x288 (PAL);

- Must have audio (mono or stereo). The sampling frequency can be 11, 22, or 44 kHz

Note that there are now VideoCD Profiles (one for NTSC, one for PAL) available in the Profile Manager. To get the best quality out of your video, make sure that your original source AVI is as noise-free as possible, with as little compression as possible. Because you won't be able to adjust the bitrate to increase quality, set Performance to "Very Slow" to allow Motion Estimation to provide the best quality.

For more information on making and playing VideoCDs, see our MPEG Resources page.

What is DVD? Aren’t MPEG-2 files DVD files?

"DVD" stands for Digital Versatile Disc, but is more commonly known as Digital Video Disc. Like VideoCD, DVD is a specification for a player and a disc that delivers video content.  The DVD disc looks similar to a CD, but is capable of holding much more data (@4.7 GB for DVD vs. @650 MB for CD). As a result, DVD is capable of delivering much more video content at higher quality than CD.

DVD-Video primarily uses a restricted subset of ISO 13818-2 MPEG-2 constant or variable bit rate video. It can also use MPEG-1 video, but is primarily associated with MPEG-2.  DVD-Video also utilizes MPEG-1 audio layer II elementary streams (ISO/IEC 11172-3) 48 kHz/s, or Dolby Digital ™ AC-3 5.1 channel audio at 48 kHz/s. Although DVD supports a data rate transfer of up to 9.8 Mb/s, DVD-Video is generally a variable data rate of 4.7 Mb/s .

Although MPEG-2 is a part of DVD, it is by far not the only element. DVD authoring packages import MPEG files and create “vob” (video object) files for use in DVD Video. In addition, DVD Video includes a great deal of other data types such as multiple languages, subtitles, parental control, region codes, encryption, navigation tools, etc.. All of these must be synchronized and organized under a very specific set of parameters.

Can LSX-MPEG Encoder make DVDs, DVD-Video, or VOB files?

LSX-MPEG Encoder makes MPEG files that are compliant for use in the DVD authoring process, but DVD specific authoring tools and systems are still required to complete a DVD project. At this time, LSX-MPEG Encoder does not output VOB files. For more information DVDs and DVD production, see our MPEG Resources page.

What are the specifications of DVD Video? How can I make my MPEG files compliant for import into DVD authoring applications?

The DVD specification is a closely held document, available only for purchase from Toshiba. Some information is public, however, and will help you produce video that can be considered “DVD complaint”:

- MPEG-1 (SIF) or MPEG-2 (MP@ML)

- Video data rate is generally an average of 4.7 megabits per second, but never any greater than 9.8 Mb/s

- MPEG-2 video may be CBR or VBR, but MPEG-1 is CBR only

- Video packet size is 2048 bytes

- Buffer size 1.8535008 Mbits for MPEG-2 max, 327689 bits for MPEG-1

- One of the following three formats:

NTSC - 720x480, 704x480, 352x480, 352x240 (MPEG-1), 29.97 fps

PAL - 720x576, 704x576, 352x576, 352x288 (MPEG-1), 25 fps

- GOP structure:	Max of 36 fields or 18 frames (NTSC)

 	Max of 30 fields or 15 frames (PAL)

Max distance between I frames,  3   (i.e.  IBBPBBPBBP, ...)

Every GOP must have a Sequence Header

- Aspect ratio: 4:3 or 16:9 (2.21:1 not permitted)

- MPEG 1 audio layer II elementary streams (ISO/IEC 11172-3)

Sampling Frequency - 48 kHz, 16 bits per sample

Mono (32 to 192 kb/s) and Stereo (64 to 384 kb/s)

These are only general guidelines. In most cases, your DVD authoring application will guide you through these settings automatically, or provide documentation regarding specific requirements it has for your MPEG streams. Ligos is beginning testing on a number of DVD authoring applications with LSX-MPEG Encoder, and will post results and tips on our website in the near future. For more information DVDs and DVD production, see our MPEG Resources page.

How do I ensure maximum compatibility of the output MPEG file with different hardware and software MPEG players?

The output MPEG files created by the LSX-MPEG Encoder are compliant with the MPEG standard specification. Most MPEG players, however, can play only those MPEG files that are within some limited subset of encoding parameters. Most free software and low cost hardware MPEG players, for instance, play only Constrained Parameters MPEG-1, or MPEG-2 files that meet the constraints of a certain Profile and Level. It is a good idea to try to create only MPEG-1 files that are compliant with the constrained parameters whenever possible. There could be some other limitations for different players.

For example, some hardware players fail to play MPEG files if frame sizes (width and height) are not a multiple of 16. The MPEG standard specification itself does not have any limitation on possible width and height values other than a value less than some particular maximum value. The LSX-MPEG Encoder can accept AVI files and create MPEG files with any even value of frame width and height. But taking into account the problem with some players mentioned above, it may be a good idea to create files with a frame width and height that is a multiple of 16, for example 320 x 240 or 160 x 112.

Some hardware MPEG players fail to decode MPEG system streams with a pack size larger than a CD-ROM sector size of 2324 bytes, even though the MPEG standard specification itself allows pack sizes up to 4096 bytes. So for compatibility with such players, set the system stream pack size less than or equal to 2324 bytes. The default value of the pack size in the LSX-MPEG Encoder is 2048 bytes.

LSX-MPEG Encoder has two distinct modes for controlling video data rate: the default Constant Bitrate (CBR) and Variable Bitrate (VBR). It is recommended that you reserve use of VBR for MPEG-2 files, as some MPEG-1 players are capable of playing only CBR MPEG-1 files.


Error and Warning Messages

LSX-MPEG Encoder

Failed to decompress AVI video stream. Possible reason: cannot find appropriate video codec. AVI file may be corrupted or uses an unsupported video compression format. Please specify valid input file name and directory.

This error is generated when Windows is unable to decode the AVI input file. The most common cause is that the AVI was compressed with a codec that is not installed on the system being used. You can check this by trying to play the file with Active Movie or Windows Media Player, or by checking for the codec in the Windows Control Panel Multimedia settings. In order for LSX-MPEG Encoder to decode the file for the transcoding process, the same AVI codec must be properly installed on the same system.

Output directory "..." does not exist or not available. Please set valid output file name or directory. Temporary file names will be changed according to new output name.

The output file must be specified in an existing directory. If you need to specify the output file in a new directory, create a new directory before setting a new file name.

Output file "..." can’t be created. Possible reason: device is a network drive that does not support long file names or available for read only access. Would you like to specify another temporary file name?

or

Temporary audio (video) file ".." cannot be created. Possible reason: device is a network drive that does not support long file names or available for read only access. Would you like to specify another temporary file name?

These error messages may appear when the user selects a new output file name or after the user selects a new input file name. The temporary file names for video and audio streams are assigned based on their specified output file name and directory. The system may not be able to create a temporary file on a network drive if  the specified drive does not support long file names or file names containing illegal characters.

Output device or directory "..." is read only. Please set valid output file name. Temporary file names will be changed according to new output file name.

Generally, you’ll get this message if the system cannot create the specified output file because it is located on a read only or CD-ROM drive. This error message commonly appears when the user selects an input AVI file from a CD-ROM drive. Select an alternate location for the correct output file.

File name "..." already exists and does not have write permission. Would you like to specify another output file name?

A file with the output file name already exists and has read only access permissions.  Select an alternate output file name in this dialog box. Alternatively you may prefer using the File Manager or some other system tool to change access permissions of the specified file if it is possible.

Fatal error during multiplexing: cannot open file "..." for write operation. Permission denied. File or device is read only.

This error message may appear during MPEG encoding when the Encoder combines the temporary audio and video files. The directory or device may have read only permission, or have become unavailable during encoding. Specify a different output file name or directory.

Maximum P (B) frame horizontal (vertical) motion vector must be positive, multiple of 8. Please correct maximum horizontal motion vector.

The maximum motion vector must be a positive integer value, multiple of 8. Reset to correct values in the Motion Vectors tab.

Illegal number of input frames <1. Please set correct number of frames to encode.

The specified number is negative or an incorrect character has been entered. Reset to a legal number of frames.

The first frame number is greater than the number of frames in the input file. Valid 1st frame number must be from 1 to n please correct first frame number.

The maximum first frame number must equal the (number of frames in the input file) -1. Set the correct number for the first frame to encode.

The last frame (first frame + number of frames to encode) is greater than the number of frames in the input file. There are a maximum of n frames.

The number of the first frame plus the number of frames to encode must be less than or equal to the number of frames in the input file.

Constrained parameters error: Encoding parameters for the MPEG video stream do not satisfy constrained parameters specification: [description of particular error, example 1] image area > 396 macroblocks (W*H>101376, where W and H are width and height rounded up to the nearest multiple of 16). The program cannot encode an MPEG-1 constrained parameters video stream with these parameters. Open the "Advanced" property sheet and disable the "constrained parameters" option in the MPEG-1 property page or change some video stream parameters before encoding. Warning: Some MPEG-1 players may not be able to play MPEG video streams that do not satisfy the constrained parameters specification.

This error message appears when the user specifies encoding parameters that do not satisfy the MPEG-1 Constrained Parameters specification. This particular error appears because the frame Width * Height is larger than the maximum value specified by constrained parameters. LSX-MPEG Encoder can create MPEG-1 files with parameters that exceed the limitations of Constrained Parameters, but you must disable the "constrained parameters" option in the Advanced options MPEG-1 property page. Note: some software MPEG players and low-end hardware players will not play MPEG files if some parameters exceed the limitation of constrained parameters.

Constrained parameters error: Encoding parameters for the MPEG video stream do not satisfy constrained parameters specification: [description of particular error, example 2] video stream data rate > 1856000 bits/sec (approximately equals to 1812 kbits/sec). The program cannot encode MPEG-1 constrained parameters video stream with these parameters. Open the "Advanced" property sheet and disable the "constrained parameters" option in the MPEG-1 property page or change some video stream parameters before encoding. Warning: Some MPEG-1 players may not be able to play MPEG video streams that do not satisfy the constrained parameters specification.

This particular error appears because the specified video stream data rate exceeds the MPEG-1 Constrained Parameters limit. You can reduce the specified data rate to the maximum value 1812 Kbits/sec allowed by the Constrained Parameters specification, or disable the "Constrained Parameters" option in the MPEG-1 Advanced property page


Understanding
What is MPEG?

LSX-MPEG Encoder

MPEG-1 and MPEG-2 are motion video compression standards created by the Moving Picture Experts Group. This group is a joint committee of the International Standardization Organization and the International Electrotechnical Commission.

The MPEG-1 Standard, completed as a draft in 1992, defines a bit stream of compressed audio and video data with a data rate of 1.5 Mbits/sec as being suitable for CD-ROMs and VideoCD applications. It is possible to generate MPEG-1 streams with other data rates. The MPEG-1 Standard is formally described in ISO/IEC 11172.

The MPEG-2 Standard was designed later for digital transmission of broadcast quality video with data rates from 2 to 10 Mbits/sec. It was written to be more “generic”, that is to address a broader range of applications, and is the compression standard for DVD and various digital television systems. The MPEG-2 Standard is described in ISO/IEC 13818 documents.

MPEG-1 and MPEG-2 motion video compression standards are based on the interframe method of compression. This means that some frames are encoded based on representing changes comparatively to another previously encoded frame(s). Since usually only a small portion of the frame changes, it helps to reduce the amount of data to be stored.

Take for example, an AVI file of 30 frames per second. Each frame is a standalone picture, and does not reference any other frame. If we use the letter “I” to represent a frame, a single second could then be represented like this:

(I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I)

…with 30 “I”s representing each individual frame.

An MPEG stream can have three types of frames: Intra (I) frames are coded without any references to any other frames. Predicted (P) frames reference previously encoded P or I frames, and encode only the changes. Predicted frames provide significantly better compression than Intra coded (I) frames. Bi-directional interpolated (B) frames contain references to both previous P or I frames and the next P or I frame. Bi-directional frames provide the best compression. The three frame types and their sequence (for instance, I BB P BB P BB P BB), represent a Group of Pictures (GOP).

Using the superior compression of GOP structures, therefore, the same second in MPEG might be represented like this:

(I BB P BB P BB P BB P BB,  I BB P BB P BB P BB P BB)

…with two GOPs. Both of the examples contain 30 frames, but the MPEG file will be significantly smaller due to the use of P and B frames.

An MPEG encoder can gather most of the information for the group of similar pictures from the first frame in a scene and encode that as an I frame. The encoder could continue to encode each of these frames as an I frame, but it is much more efficient to only record data about the pixels that have changed. The encoder might then look ahead to the fourth frame, note only the things that changed in #1 and #4, and record those few changes as a P frame. Finally, the encoder can analyze the I and the P frame, and from that create very small B frames for frames #2 and #3. Because video generally has 24-30 fps, GOP structures can get quite complex. In addition, the encoded order of frames is not always the same as the display order, and many GOPs will be required to accurately portray just a few seconds of video.

This encoder analysis is a process known as motion estimation, and LSX-MPEG Encoder has the most robust motion estimation methods available in software. As a result, LSX-MPEG can produce files that are both smaller and better looking than other alternatives.

To encode an MPEG file, many other parameters of the MPEG video stream must be specified. Among these Advanced parameters are:

-	the frame rate of the video

-	the resolution (frame size) of the video

-	video and audio data rate, which is an average amount of data transferred in an MPEG stream per unit of time (usually kilobits or megabits per second)

-	the amount of P frames that are to be stored between every pair of I frames

-	amount of B frames that are to be encoded between every pair of P frames

-	maximum vertical and horizontal motion vector values for P and B frames, which are necessary to limit the area covered by the motion estimation process

See the section Constrained Parameters, Profiles & Levels to learn more about the meaning and requirements of MPEG parameters and see sections Main program window and Advanced parameters dialog box to learn how to enter the required parameters in the LSX-MPEG Encoder program.


Constrained Parameters
Constrained Parameters, Profiles & Levels

LSX-MPEG Encoder

Although it is possible to create MPEG-1 files with frame sizes of up to 4095x4095 and data rates greater than 1812 kbits/sec, not all decoders can play such MPEG-1 streams. There is a minimum required set of parameters of MPEG-1 streams that many low-end hardware and software MPEG-1 players usually support. The minimum set of parameters is specified below as "constrained parameters".

A constrained parameter bitstream is defined in the MPEG-1 Standard as following:

* Horizontal frame size less than or equal 768 pixels.
* Vertical frame size less than or equal 576 pixels.
* Picture area less than or equal 396 macroblocks (101376 pixels).
* Frame rate less than or equal 30 frames/sec.
* Motion vectors less than or equal 64.
* Bitrate less than or equal 1.86 Mbits/sec
* VBV buffer size less than or equal to 40 Kbytes/sec. (40 Kbytes/sec for constrained files and 224 Kbytes/sec for non-constrained files.)

Constrained Parameters do not apply to MPEG-2 streams, as they have broader applications than CD-ROM or VideoCD. MPEG-2 was designed to be a very generic standard in that it is to be used for a variety of applications, everything from DVD and computer video to digital satellite and HDTV systems. MPEG-2 does, however, have defined Profiles and Levels of compatibility. Profiles specify syntax (i.e. algorithms), and Levels specify coding parameters (sample rates, frame dimensions, coded bitrates, etc.). Defined together, Profiles and Levels specify interchange standards for specific applications of MPEG-2.

As shown in the table below, there are 5 Profiles (Simple, Main, SNR, Spatial and High), each with a maximum of 4 possible Levels (Low, Main, High-1440, and High). Not all combinations have been defined in the MPEG-2 specification. MPEG-2 Main Profile at Main Level (MP@ML) can be considered similar to MPEG-1's constrained parameters, and supports up to 720 pixels x 480 lines x 30 frames/sec, at a total sampling rate up to 10.4 Msamples/second (i.e., consistent with the CCIR-601 video format standard).

The MPEG-2 tab in the Advanced Parameters dialog has the following predefined Profile/Level combinations:

-	Main Profile at Low Level

-	Main Profile at Main Level (default)

-	High Profile at High 1440 Level

-	High Profile at High Level

If compatibility with a specific MPEG-2 application or decoder is important in your work, be sure to specify the correct parameters, and the correct Profile/Level combination. The following table shows the MPEG-2 Profile (horizontal) / Level (vertical) cross-reference structure, along with the values that defined the upper limits of each combination. For a more in depth explanation of this systems, check the MPEG-2 specification or a reference on the subject.

	SIMPLE	MAIN	SNR	SPATIAL	HIGH
LOW	undefined	352 pels/line 288 lines/frame 30 frames/sec 3.04 Msamples/s 4 Mbits/s	352 pels/line 288 lines/frame 30 frames/sec 3.04 Msamples/s 4 Mbits/s both layers 3 Mbits/s base layer	undefined	undefined
MAIN	720 pels/line 576 lines/frame 30 frames/sec 10.4 Msamples/s 15 Mbits/s	720 pels/line 576 lines/frame 30 frames/sec 10.4 Msamples/s 15 Mbits/s	720 pels/line 576 lines/frame 30 frames/sec 10.4 Msamples/s 15 Mbits/s both layers 10 Mbits/s base layer	undefined	720 pels/line 576 lines/frame 30 frames/sec 11.06 Msamples/s or 14.75 Msamples/s 20 Mbits/s 3 layes 15 Mbits/s base + middle 4 Mbits/s base layer
HIGH 1440	undefined	1440 pels/line 1152 lines/frame 60 frames/sec 47 Msamples/s 60 Mbits/s	undefined	1440 pels/line 1152 lines/frame 60 frames/sec 47 Msamples/s 60 Mbits/s 3 layes 40 Mbits/sbase + middle 15 Mbits/s base layer	1440 pels/line 1152 lines/frame 60 frames/sec 47 Msamples/s or 62.7 Msamples/s 80 Mbits/s 3 layes 60 Mbits/sbase + middle 20 Mbits/s base layer
HIGH	undefined	1920 pels/line 1152 lines/frame 60 frames/sec 62.7 Msamples/s 80 Mbits/s	undefined	undefined	1920 pels/line 1152 lines/frame 60 frames/sec 62.7 Msamples/s or 83.5 Msamples/s 100 Mbits/s 3 layes 80 Mbits/s base + middle 25 Mbits/s base layer


LSX-MPEG Player

LSX-MPEG Encoder

The LSX-MPEG Player is a DirectShow compatible filter for the playback of MPEG-2 streams (MPEG-1 and MPEG audio support is already provided by Microsoft's own decoders). It was installed as part of the installation process of LSX-MPEG Encoder. The filter provides quality playback of MPEG-2 directly through Microsoft's Windows Media Player or ActiveMovie (not included).  LSX-MPEG Player makes an ideal companion to Ligos' LSX-MPEG Encoder - combined, the two provide a complete MPEG encoding and playback solution.

There is no “standalone” application for the LSX-MPEG Player. Instead, it is installed and registered on your system in a fashion similar to a video codec. In order to playback MPEG-2 files, simply double-click on the file, and it will open in your default media player. The media player will detect the MPEG-2 stream, and an MPEG-2 splitter will send the video portion to the LSX filter for decoding. MPEG-1 audio playback is decoded using Windows standard MPEG audio decoder.

The LSX-MPEG Player includes a configuration utility to fine-tune your MPEG-2 playback. This is accessed in the LSX-MPEG Player group by clicking on "LSX-MPEG Configuration". A dialog will open with information and options about configuring the filters for optimum playback. In most cases the default options ("Fast" Playback, "Connect to Ligos Splitter Only", and "Play MPEG-2 Only" should work fine. See the utility interface for details.

The LSX-MPEG Player does have settings, which you can use to control performance and quality. In order to access them, open up an MPEG-2 file in your media player, and go to the Properties menu of the player. Access the display for the filters in use, and open the Ligos MPEG Video Decoder.

The filter properties dialog for the Ligos MPEG Video Decoder has a number of options for controlling playback efficiency and functions.

Movie Info – Displays information regarding the currently loaded clip, including MPEG Video type (format), Picture size (in pixels), Bit rate (video data rate only), and Frame Rate in frames per second.

Playback Mode – Allows you to choose between Fast loading and playback (default), or Stable. The Fast setting enables playback to begin immediately. The Stable setting allows a pause while video data is fed to the video card. Most video cards have no problem with the Fast setting. If you are experiencing immediate crashing when MPEG-2 videos begin to play, change to Stable mode.

Playback Options – Provides additional controls for the functionality of the filter. Connect to Ligos splitter only (default) overrides the Microsoft default routing of MPEG-2 video, and should not be adjusted unless you are experiencing problems with other MPEG-2 decoders (such as software DVD devices) on your system. Play MPEG-2 Only is the default setting that determines what format of MPEG the Ligos Player filter will decode. Unchecking it provides support for MPEG-1 video as well, but overrides Microsoft’s default MPEG-1 decoder. Use Overlay Mixer (off by default) can be activated to provide better performance, but only works with a few video card and DirectX driver combinations. If you are experiencing unexpected slow performance (dropped or skipped frames), try activating this mode.

As a software decoder, performance of the LSX-MPEG Player is dependent on the robustness of your system. It is designed to perform real time decoding of MPEG-2 (Main Profile@Main Level) video bitstreams up to 10 Mbps. It supports playback of up to Full D-1 resolution files, NTSC (720x480, 30fps) or PAL (720x576, 25 fps) on a minimum Pentium II 450 MHz system. You must have a DirectX compatible video card with the most recent drivers supporting DirectDraw and YUV overlay mode. On a 300 MHz Pentium II, you should be able to playback a Half D-1 file (352x480 NTSC, or 352x576 PAL) at full frame rate. We will continue to optimize and improve the LSX-MPEG Player over time, so be sure to check back on our website on a regular basis for updates.

PLEASE NOTE:  LSX-MPEG Player is not intended to be a software DVD or VOB player, and that functionality is not supported. Although MPEG-2 is the basis of DVD Video (stored as VOB files), there is more to DVD than simple MPEG-2, and the Player was not designed or tested to support DVD.

LSX-MPEG Player is simply intended to allow you to play back MPEG-2 Program Streams in Active Movie Media Player or Windows Media Player. Playback of Transport streams is not supported at this time. The Ligos MPEG Splitter sends the MPEG-2 video to the Ligos MPEG Video decoding filter for playback, and sends the audio stream to Windows default audio decoder. The Player can also be configured to playback MPEG-1 video, but in most cases, Windows default MPEG-1 decoder will work just as well.

In addition, the Player was not intended to support playback of MPEG-2 within other applications (such as Adobe Premiere, Director, PowerPoint, etc.). As there are a number of applications out there that interface multimedia and Windows through different APIs, there is no way we can support or test them all. In many cases it may work, but it's not a supported function.

The Player is known to work with Windows NT 4.0 in many circumstances, but is not supported on NT due to version incompatibility issues with DirectX. If you are trying to use the Player under Windows NT, make certain that you have the latest version of NT Service Pack installed properly. We hope to be able to resolve this issue in the future with the release of Windows 2000.


MPEG ResourcesK MPEG-1
MPEG Resources

LSX-MPEG Encoder

MPEG is an enormous topic, far more than can be covered by a single application or this Help file. Here are some additional resources to further your understanding of MPEG, and your utilization of the LSX-MPEG Encoder.

Books

Haskell, B.; Puri, A.; Netravali, A.; Digital Video: An Introduction to MPEG-2; Chapman & Hall, 1997.

Orzessek, M.; Sommer, P.; ATM & MPEG-2: Integrating Digital Video Into Broadband Networks; Hewlett-Packard Professional Books, 1998.

Symes, P.; Video Compression; McGraw-Hill, 1998.

Magazines

AV Video Multimedia Producer- http://www.avvideo.com/

Camcorder & Computer Video – Miller Magazines, 4880 Market St., Ventura, CA  93003

Computer Videomaker - http://www.videomaker.com/

DV (Digital Video) - http://www.dv.com/

Videography - http://www.vidy.com/

Internet

Ligos Technology – http://www.ligos.com/ ; check out our new MPEG Zone at http://www.ligos.com/mpeg_zone/ ! ;

Interactive Technology Primer – http://tlc.nlm.nih.gov/resources/publications/primer/primer.html ; the most complete guide to the “big picture” of multimedia

MPEG Group FAQ -- http://www.crs4.it/~luigi/MPEG/ ; MPEG FAQs and standards

MPEG.org – http://www.mpeg.org/ ; MPEG Pointers and Resources

Berkeley Multimedia Research Center –

MPEG-1 FAQ - http://bmrc.berkeley.edu/frame/research/mpeg/faq/mpeg1.html

MPEG-2 FAQ - http://bmrc.berkeley.edu/frame/research/mpeg/faq/mpeg2.html

Russil Wvong’s VideoCD –  http://www.greenspun.com/bboard/q-and-a.tcl?topic=Video%20CD ;

Great discussion board for making and playing VideoCDs

John McGowan’s AVI Overview – http://www.rahul.net/jfm/avi.html ; Probably the best resource anywhere on details regarding the AVI format

Trixter's Desktop MPEG Authoring FAQ – http://www.oldskool.org/mpeg/mpegfaq.html

Flexion – http://www.flexion.org/ ; another great site for VideoCD information

DVD FAQ at Videodiscovery – http://www.videodiscovery.com/vdyweb/dvd/dvdfaq.html ; the basics of DVD

A Day at the DVD Forum – http://reality.sgi.com/nemec/dvd.html ; technical notes on the requirements of MPEG-1 and MPEG-2 for DVD applications, highly recommended

Disctronics and Freehand DVD Video website - http://www.dvd-video.co.uk/ ; technical documents on DVD Video specifications and requirments

Markus Zingg’s AVI_IO – http://www.nct.ch/multimedia/avi_io/ ; excellent shareware application that works around the AVI 2 GB file size problem

Camel’s MPEGJoin – http://extra.newsguy.com/~theprof/Readme.html ; useful utility for joining MPEG streams together


Glossary

LSX-MPEG Encoder

.m1v
.m2v
.mp2
.prg
AVI files
B frame
codec
concatenation
constrained parameters
data rate
encode
filters
frame number
frame rate
high color video
I frame
image quality
inverse telecine
low color video
macroblock
motion estimation
motion vectors (horizontal and vertical)
motion vector property page
MPEG-1
MPEG-2
P frame
performance property page
picture area
quantization
sequence property page
3:2 pulldown
true color video
VideoCD
video stream


m1v file
What is .m1v?

LSX-MPEG Encoder

M1V is the default file extension for MPEG-1 motion video files created by the LSX MPEG Encoder.


m2v file
What is .m2v?

LSX-MPEG Encoder

M2V is the default file extension for MPEG-2 motion video files created by the LSX MPEG Encoder.


mp2 file
What is .mp2?

LSX-MPEG Encoder

MP2 is the default file extension for MPEG-1 audio stream (Layer 2 only) files created as temporary files by the LSX MPEG Encoder. They can be retained after encoding by adjusting settings in the Files tab of the Advanced Parameters dialog, and used as Audio only MPEG files.


prg file
What is .prg?

LSX-MPEG Encoder

PRG is an alternate file extension for multiplexed video and audio MPEG-2 files created by the LSX MPEG Encoder.


AVI file
What is an AVI file?

LSX-MPEG Encoder

An AVI file is the motion video file format used by Microsoft Video for Windows.


B Frame
What is a B Frame?

LSX-MPEG Encoder

Bi-directional interpolated (B) frames are frames in an MPEG video stream that contain references to both previous P or I frames and the next P or I frame. Bi-directional frames provide the best compression of the three frame types.


codec
What is a codec?

LSX-MPEG Encoder

A codec is a driver used to decode (or encode) motion video with some specific kind of video compression. Some codecs are software only, and some may be hardware dependent, i.e. may require some particular hardware to be installed (for example Motion JPEG capturing board ).


concatenation
What is concatenation?

LSX-MPEG Encoder

The act of taking two separate files (in this case video clips) and splicing them together so that they make one file is called concatenation.


data rate
What is data rate?

LSX-MPEG Encoder

Data rate is the amount of data transferred by some information media in a unit of time.


encode
What does encode refer to?

LSX-MPEG Encoder

The process of reducing the size of data by means of some data compression algorithm.


frame number
What is a frame number?

LSX-MPEG Encoder

Refers to the sequence of frames in a video file. The first frame in the file would be called the first frame. The last frame in the file would be called the last frame, and all frames in between could be given a numerical value as to the number of frame in the file.


frame rate
What is frame rate?

LSX-MPEG Encoder

The default frequency (in seconds) of image frames in motion video.


high color video
What is high color video?

LSX-MPEG Encoder

In this manual: a display mode that provides color resolution of 16 bits per pixel.


I frame
What is an I frame?

LSX-MPEG Encoder

Intra (I) frames are frames in an MPEG video stream coded without any reference to any other frames.


image quality
What is image quality?

LSX-MPEG Encoder

In this manual: image quality is an objective or subjective measure of how different input video frames and encoded frames in the output MPEG file are. There are no assumptions about the quality of the input frame. In this program, measure of quality is based on the average sum of square values of differences of pixels on input and output frames. When applied to an input AVI file, the term quality is a measure of how much different the original captured video frames and video frames after encoding are.


low color video
What is low color video?

LSX-MPEG Encoder

In this manual: a display mode that provides color resolution of 8 bits per pixel or less.


macroblock
What is a macroblock?

LSX-MPEG Encoder

The fundamental unit within an MPEG video stream used for motion prediction. A macroblock represents the data in a picture area with a standard size of 16 x 16 luminance pixels.


motion estimation
What is motion estimation?

LSX-MPEG Encoder

A method of reducing the amount of data representing P or B frames in an MPEG video stream by means of searching for every macroblock on the current P or B frame that is most similar to a macroblock on previous and/or following P or I frames.


motion vectors
What is a motion vector (horizontal and vertical)?

LSX-MPEG Encoder

Values representing coordinates of macroblocks on previous and/or following I or P frames associated with a current macroblock as a result of motion estimation.


MPEG-1
What is MPEG-1?

LSX-MPEG Encoder

International standard on motion video and audio encoding ISO/IEC 11172.


MPEG-2
What is MPEG-2?

LSX-MPEG Encoder

International standard on motion video and audio encoding ISO/IEC 13818.


P frame
What is a P frame?

LSX-MPEG Encoder

Predicted (P) frames are frames in an MPEG video stream that reference previously encoded P or I frames, and encode only the changes. Predicted frames provide significantly better compression than Intra coded (I) frames.


picture area
What is picture area?

LSX-MPEG Encoder

Picture area refers to the actual pixel area on the screen the image takes up. This can also be called the frame size or resolution.


quantization
What is quantization?

LSX-MPEG Encoder

Quantization is the process of limiting the value of a function to a predetermined value, like rounding a number. In video encoding, quantization determines the extent of frequencies to be analyzed in the video.


3:2 pulldown
What is 3:2 pulldown?

LSX-MPEG Encoder

3:2 pulldown is the process of transferring 24 frames/s film to 30 interlaced fps NTSC video. It is not used in PAL video, which instead simply speeds up the source to 25 frames/s. Five fields of video are generated for each pair of film frames, resulting in the 60 fields/s used by NTSC video. This results in duplicated frames. The process of undoing 3:2 pulldown for efficient MPEG video encoding is known as inverse telecine.


true color video
What is true color video?

LSX-MPEG Encoder

In this manual: a display mode that provides color resolution of 24 or more bits per pixel.


VideoCD
What is VideoCD?

LSX-MPEG Encoder

VideoCD is a Compact Disc MPEG-1 format which was defined by Philips and JVC, and is also known as 'White Book'. VideoCD can store video sequences and high quality stereo sound in up to 98 A/V tracks. It is generally playable on all CD-ROM players and the most recent generation of DVD (Digital Versatile Disc) players. LSX-MPEG Encoder can produce VideoCD files, but in order for the option to appear, your input file must match the following requirements of a VideoCD file:

-	Frame size must be either 352x240 or 352x288;

-	Must have audio (mono or stereo). The sampling frequency can be 11, 22, or 44 KHz


video stream
What is a video stream?

LSX-MPEG Encoder

A portion of an MPEG file that represents motion video (only) information.