VidCon32 Help Contents

You can use VidCon32 to capture video sequences and images from your capture board. To learn how to use Help, press F1.

About VidCon32

Introducing VidCon32

Capturing Video

Tips for Improving Video Quality

VidCon32 Controls

VidCon32 Toolbar and Controls

File Menu Commands

Edit Menu Commands

Options Menu Commands

Capture Menu Commands

Help Menu Commands

Configuring VidCon32

Adjusting the Look of VidCon32

Setting Video Display Options

Setting the Video Source

Setting Up for Video Capture

Overview: Setting Up for Video Capture

Preparing the Capture File

Setting Audio Options

Setting Video Options

Setting Compression Options

Setting the Palette

Testing the Setup

Capturing Video

Overview: Capturing Video

Capturing a Video Sequence Manually

Capturing a Video Sequence Automatically


Introducing VidCon32

VidCon32 is a data-capture application that lets you capture and playback video sequences  onto / from your computer system. With VidCon32, you can capture individual images or entire video sequences from a VCR, a videodisc player, or a video camera and microphone.


Capturing Video

Capturing one or more frames of an audio-video sequence  involves setting up audio and video sources, supplying capture settings to VidCon32, and performing the actual capture session. You'll first need to perform the following tasks:

1. Connect the audio and video sources to the capture board  and audio board. For more information, see the documentation for your capture board.

2. Configure frame display and video source options for VidCon32. For more information, see the topics beginning with Configuring VidCon32.

3. Set up the capture file, and set options for the video sequence. For more information, see Setting Up for Video Capture.

4. Capture the video sequence.

5. Use the Playback button to edit the captured sequence

Capture Methods

VidCon32 provides two modes for capturing video sequences:

•	Real-time capture

•	Step--frame capture

Real-time capture processes a video sequence and audio as the events occur naturally, or as the video source plays without interruption. Step-frame capture pauses the video source as it collects each frame (image) of data, and, if audio is also selected, rewinds the media in the video source and collects audio data as the video source plays a second time.

Real-time Capture

A video source for real-time capture (such as a video camera or videodisc) provides an uninterrupted stream of information to the capture hardware. The capture hardware copies each frame of the video sequence (and each portion of audio) and transfers it to disk before the next frame of data enters the capture hardware. A video frame contains one image of the video sequence.

Real-time capture demands a fast computer and hard disk. The computer must process and store the incoming video frame before the next frame is received in the capture board. If the system falls behind during capture, frames of video data are dropped (lost).

Step-Frame Capture

Step-frame capture collects video frames from a video sequence in a series of steps. In step-frame capture, frames are captured one at a time, generally from a paused video device. You can perform step-frame capture manually, advancing the video source using the controls on the video device. VidCon32 also provides automatic step-frame capture for video devices that support the Media Control Interface (MCI). With this method, VidCon32 issues frame-advance commands to the source device and captures the sequence frame-by-frame. When VidCon32 finishes capturing the current frame, it advances the video source to the next capture point.

Step-frame capture provides an alternative for systems that cannot process a video sequence in real time. Because the system can fully process a video frame before contending with the next, you can use larger frame sizes and color formats, and you can optionally compress the video sequence during capture. When a step-frame capture is complete, you can capture the audio segment associated with the video frames by playing the source video a second time.


Tips for Improving Video Quality

In addition to mastering the basics of capturing, editing, and compressing video, you should know how to adjust the physical elements of the recording set to improve the recording quality of your digital-video clips. The following sections provide tips for improving the quality of your videos. You should consider the following areas:

Lighting

Video-source quality

Audio-source quality

Recording distortion

Compression Considerations

Using Lighting Effectively

While many cameras can be adjusted for low-light conditions, a well-lit scene vastly improves video quality. Improved lighting makes colors richer; details appear clearer. Also, many computer monitors cannot display subtle differences in low-light scenes, especially when compared to TV or video monitors.

Although shadows play an important role in traditional film-lighting schemes, they can greatly increase the storage and data-transfer requirements for digital movies. Shadows increase the number of color variations from frame to frame, thus increasing the amount of data needed to represent each frame. To reduce color variations (thereby improving playback performance), you can use a flat lighting scheme that illuminates the subject from all sides, eliminating shadows.

Improving the Quality of the Video Source

Use high-quality video formats such as Hi-8, and always use a master or first-generation tape. Subsequent generations increase background noise, which not only affects playback quality, but results in lower compression ratios. Remove all sources of noise from your video by cleaning the playback head on your VCR, by connecting your computer, VCR, and camera to a common ground, and by using shielded cables.

Improving Audio Quality

Check the level of the your audio using the Level button in the Audio Format dialog box. You should adjust the audio level so that the loudest audio passages are about 80% of the full range. Also, you should make all of your recordings at a consistent audio level.

Retaining Detail in the Video Sequence

All forms of digital recording are subject to distortion known as aliasing. In digital video, this distortion appears as moire patterns, or other visual effects. Aliasing happens when the sampling rate is insufficient to capture all the data coming in from the analog-video source.

Capturing video images at 320-by-240 or 160-by-120 resolution can result in the loss of fine detail within the video image. For example, at 160-by-120 resolution, only every fourth line of an incoming video signal is retained. Thin lines in the image (for example, telephone poles) can be dropped entirely.

Some video-capture hardware uses low-pass filters to reduce aliasing as the size of the capture window is reduced. If your video-capture hardware does not include anti-aliasing filters, try the following:

Use the 2x Spatial averaging technique provided by VidCon32. You can use this technique when capturing from video-source devices that support the Media Control Interface (MCI). For more information, see Controlling the Video Source During Automatic Capture.

When recording finely detailed objects, zoom-in as close as possible.

Avoid using materials in your video sequences that contain patterns; for example, venetian blinds, tiles, checker boards, and plaids.

Reducing Color Distortion

When capturing using the 8-bit video format, which uses a 256-color palette, you might experience flickering caused by color variations produced by the analog-to-digital conversion. These variations aren't as apparent in the 16- or 24-bit formats. To reduce flickering when capturing 8-bit sequences, you can use a VidCon32 averaging technique available when capturing frames from an MCI-supported source device. For more information, see Controlling the Video Source During Automatic Capture.

Compression Considerations

By recording clips that compress well, you can create smaller compressed files, as well as reduce the load on system resources during playback. Use the following guidelines to improve compression:

 Minimize the amount of the image that changes between frames.

A static landscape clip produces great compression ratios. Panning or zooming the camera while recording decreases the compression ratio.

 Use broad areas of constant color, which compress better than fine-grained detail.

When using backdrops, select solid colors rather than textured areas.


Video sequence

A digital- video file created using Video for Windows. Video sequences consist of a series of frames of audio and video data. When played in sequence, the images and sound produce an animated video on the computer screen. Video sequences have a filename extension .AVI, for Audio-Video Interleaved.


Frame

A single unit of information within a video sequence. A video sequence consists of many frames of video and audio data; when the frames are played in sequence, you see an unbroken video sequence with accompanying audio playback.


Capture board

A piece of computer hardware that receives video signals and stores incoming video images in a memory area that can be accessed by system and application software.


Media Control Interface (MCI)

A standard control interface for multimedia devices and files. MCI lets a multimedia application control a variety of multimedia devices and files. VidCon32 uses MCI to play video previews and to control source devices such aslike laserdisc players and videocassette recorders.


Compression

Compression reduces the storage requirements of a video sequence. Compression reduces the file size of the video sequence and also reduces the amount of data that needs to be transferred to play a video frames. Since some storage devices (particularly CD-ROM drives) have a relatively low data-transfer rate, reducing the amount of data that must be transferred helps avoid skips and slowdowns during playback.


VidCap Toolbar and Controls
VidCon32 Toolbar and Controls

Click the controls in the following illustration for an explanation of the VidCon32 controls:


Menu Bar

Contains a list of menus. You open menus and then choose commands from them to instruct VidCon32 to perform actions.


Preview Video button

Displays the captured frames in the VidCon32 display area (same as the Preview Video command on the Options menu).


Overlay Video button

Displays the video signal in the VidCon32 display area (same as the Overlay Video command on the Options menu).


Capture Single Frame button

Captures the current frame from the video board and displays it in the frame area (same as the Single Frame command on the Capture menu).


Capture Frames button

Manually captures a sequence of frames (same as the Frames command on the Capture menu).


Capture Setup button

Opens the Capture Setup menu of details concerning video and audio capturing


Playback button

Playback of the last recorded video sequence


Record button

Starts video capturing. Capturing can be stopped by using the right mouse button or the <escape> key


Full-screen button

Switches to an appropriate desktop resolution with full-screen display of the video signal


File Menu Commands

The File menu contains the following commands:

Command	Description
Load Palette	Imports an 8-bit color palette for use in the video sequence. You can load a palette from a bitmap (.DIB or .BMP) file or palette (.PAL) file. The palette you load replaces the default gray-scale palette provided by VidCon32.
Set Capture File	Identifies and creates the file that stores captured video sequences.
Allocate file space	Enables you to enter an amount of disk space to set aside for the capture file
Save Captured Video As	Copies the contents of the current capture file to another file.
Save Palette	Saves the palette of the current capture file  as a palette (.PAL) file.
Save Single Frame	Saves the current frame as a bitmap (.DIB) file.
Exit	Exits VidCon32


Capture file

A file created on the hard disk for the purpose of storing captured video and audio data. This file provides storage space for the capture session, allowing the capture to proceed without taking time to allocate additional disk space for video and audio data.


Palette

A collection of color information for a picture or video sequence. Video for Windows can use an 8-bit color palette, which provides up to 256 different colors for a video frame. Video for Windows can use an 8-bit palette format. With this format, up to 256 color values can bear stored in a table. Images within the video sequence reference the entries in this table; each pixel has an 8-bit value identifying which palette color to draw. The 8-bit palette format uses less storage space than the 16-bit and 24-bit formats, which do not use a palette (rather than reference a value in a table, they store color information directly with the pixel).


Edit Menu Commands

The Edit menu contains the following commands:

Command	Description
Copy	Copies the current frame  image, including the palette, to the Clipboard.
Preferences	Lets you customize VidCon32 display settings (these settings have no effect on the video sequence).


Options Menu Commands

The Options menu contains the following commands:

Command	Description
Audio Format	Sets characteristics for the audio track of the video sequence.
Video Format	Sets the dimensions and color format of captured images.
Video Source	Sets the type of input signal supplied by the video source.
Preview Video	Sets the VidCon32 display area to display an image stored in the frame buffer .
Overlay Video	Sets the VidCon32 display area to display the video-input signal.
CaptureSetup	Opens the CaptureSetup menu of details concerning video and audio capturing


Frame buffer

The memory area on the capture board used to store video data captured from the video source signal.


Capture Menu Commands

The Capture menu contains the following commands:

Command	Description
Single Frame	Captures the current frame  from the video board and displays it in the frame area.
Frames	Manually captures video frames from the source to a capture file . You indicate each frame you want to capture as it appears in the display area.
Palette	Captures color information from the incoming video stream. Using this command, you can build a color palette   from specific images in a video stream (by manually specifying the images) or from a series of frames captured automatically by VidCon32.


Real-time capture

With real-time capture, you capture video data from a source device playing at normal speed. For real-time capture, you need a computer system fast enough to keep up with the data coming in from the source device. Data must be captured and stored on the hard disk before the next frame of information is received.


Step-frame capture

With step-frame capture, you capture video one frame at a time, generally from a paused source device. You capture a frame, advance the source device to the next frame, and then capture the next frame. Step-frame capture provides an alternative if your computer system cannot capture in real time without losing data. Step-frame capture also lets you increase the frame size, use a larger color format, or perform software compression (because, since the system has more time to store the captured data).


Help Menu Commands

The Help menu contains the following commands:

Command	Description
Contents	Displays the Contents topic of this Help file.
About	Displays the version number and copyright statement for VidCon32.


Adjusting the Look of VidCap
Adjusting the Look of VidCon32

There are several ways to customize the appearance and contents of the VidCon32 window. These settings are available from the VidCon32 Preferences dialog box.

To set editing preferences

1	From the Edit menu, choose Preferences
2	Select the visual preferences you want. For information about the preferences, see VidCon32 Preferences Dialog Box .
3	Choose OK.


VidCap Preferences Dialog Box
VidCon32 Preferences Dialog Box

This dialog box lets you configure the appearance of VidCon32. It has the following fields:

Option	Description
Background Color	Specifies which color to use for the background of the VidCon32 window.
Status Bar	Specifies whether to display the status bar at the bottom of the VidCon32 window.
Tool Bar	Specifies whether to display the VidCon32 toolbar.
Center Image In Window	Specifies whether to display the frame  image in the center of the window. If the option is cleared, the frame is displayed in the upper-left corner.
Size frame to capture window	Adapts the border of the VidCon32 window to the capture window
Maximum number Of frames	Specifies one of two settings for the largest video sequence you plan to capture. To capture sequences longer than 32,000 frames, select the 324,000 setting.
Video and audio synchronization	Adapts the video stream to the audio stream in order to get lip synchrony even in case of longer sequences
OK	Saves the preference settings.
Cancel	Closes the dialog box without saving the preference settings.


Setting the Video Source

Some capture boards  can process several types of video signals. Depending on the capabilities of the capture board, VidCon32 might provide any of the following options for specifying the video source:

 Source format (for example, RGB, composite, or SVideo)

 Video standards (NTSC, PAL, or SECAM)

 Hue, saturation, and contrast levels

These options vary among different capture boards. You should consult the documentation for your capture board.

   To set the video-source type and component levels

1	From the Options menu, choose Video Source.
2	Select the appropriate video-source options. For more information about the options, see Video Source Dialog Box .
3	Choose OK.


Video Source Dialog Box

Use this dialog box to specify the signal type and format of the incoming video signal. Options for controlling video-source signals vary among capture boards, so the options displayed in this dialog box depend on your video capture board. For information about setting the video-source attributes, see the documentation for your capture board.


Setting Video Display Options

VidCon32 can display one of the following images in its window:

  The incoming video signal (before capture)

  A preview of the captured video frames (after capture)

To display the incoming video signal in the VidCon32 window, you need a capture board  that supports video overlay. You can view the video-overlay signal to find the frames you want to include in the sequence. However, to view the captured frames, you must preview the captured video sequence.

If your capture board  lacks overlay capability, you might be able to display the video signal or the captured frames on a secondary display monitor connected to the output port of the capture board.

Note During video capture, VidCon32 places highest priority on maintaining the flow of data from the capture board to the capture file. Because displaying captured frames requires some processing resources, VidCon32 might not be able to update the display area during capture. (This is not a problem when displaying the incoming video signal using an overlay board.)

Video Display Options for Overlay Boards

When displaying the incoming video signal, you can adjust the colors, contrast, and saturation of the signal to improve the picture quality in the VidCon32 display area. These settings don't affect the quality or color of images captured; they just adjust the look of the display area.

 To display captured frames in the VidCon32 display area

From the Options menu, choose Preview Video.

Or, from the toolbar, choose the Preview Video button .

 To display the video-overlay signal in the VidCon32 display area

From the Options menu, choose Overlay Video.

Or, from the toolbar, choose the Overlay Video button .

To adjust the picture quality of an overlay display

1	From the Options menu, choose Video Display
2	Adjust the video-overlay signal characteristics as needed. For information about the options, see Video Display Dialog Box .
3	Choose OK.

Video Display Options for Non-Overlay Boards

With non-overlay boards, VidCon32 always displays the captured video frames in the display area. You might be able to connect a second monitor to the output port of the capture board and use this monitor to display either the incoming video signal or the captured video frames.

To select what to display on the output monitor

1	From the Options menu, choose Video Display.
2	Choose the appropriate signal source for the output monitor. To display captured frames (the contents of the frame buffer   on the capture card), select Frame Buffer Image.  To display the incoming video signal (from which the capture hardware builds video frames), select Video Input Signal.
3	Choose OK.


Video Display Dialog Box (Overlay Control or Video Monitor)

Use this dialog box to select options for displaying the video sequence in the VidCon32 window, or on a secondary output monitor. VidCon32 displays one of two dialog boxes for setting video-display options: Overlay Control or Video Monitor.

The Overlay Control dialog box is used with capture boards  that support video overlay  and lets you adjust the appearance of the video-source signal when displayed in VidCon32. The Video Monitor dialog box lets you choose which signal appears on the output monitor.

These options don't affect the video sequence; they just affect the display.


Video overlay

The capability of watching a video source in a window on the computer. The video signal from the VCR, camcorder, or other source device is synchronized with the computer display and displayed within a window.


Setting the Video Source

Some capture boards  can process several types of video signals. Depending on the capabilities of the capture board, VidCon32 might provide any of the following options for specifying the video source:

 Source format: (for example, composite or S-Video)

 Video standards (NTSC, PAL, or SECAM)

 Hue, saturation, and contrast levels

These options vary among different capture boards. You should consult the documentation for your capture board.

 To set the video-source type and component levels:

1	From the Options menu, choose Video Source.
2	Select the appropriate video-source options. For more information about the options, see Video Source Dialog Box.
3	Choose OK.


Overview: Setting Up for Video Capture

Before capturing video, you must perform the following tasks:

  Create a capture file

VidCon32 captures video and audio data to a capture file, which is created on your hard disk before the capture session starts. By pre-allocating a capture file, you assure sufficient space for storing incoming video and audio data.

 Select option settings for the video sequence

Your video-capture system can handle various color settings, frame sizes, and audio formats. Some capture boards  offer hardware-based assistance for compressing a video stream during capture. VidCon32 lets you take full advantage of all the performance capabilities of your capture hardware. You can adjust these settings for different video sequences, achieving the desired balance between quality, storage requirements, and data-transfer rates.

 Create a capture palette (assuming you're using the 8-bit color format)

You'll want to create optimal palettes for video sequences being played on 8-bit (256-color) systems. VidCon32 lets you create representative palettes by sampling colors appearing in one or more frames of the video source signal; you can apply these palettes during the capture process

  Test the setup

Once you've finished configuring your capture settings, you can test the setup by capturing a few test frames. Capturing and compressing video can be a time-consuming process, so it's a good idea to carefully adjust your settings up front, before you capture a lengthy sequence.

You won't have to perform all these tasks every time you capture video; most can be performed once, the first time you capture video. Later, you can adjust the settings as needed to achieve the desired playback performance. The following topics in this sequence discuss the various setup tasks.


8-bit color format

A color format in which colors are stored in a separate table called a palette. The pixels within the video frame reference the entries in the palette (rather than store color information themselves). The palette format provides a maximum of 256 unique colors within a video frame. Each color entry in the palette can use any of 16 million colors. Most multimedia computers can display 8-bit images; fewer support the 16- and 24-bit formats. The term ""8-bit"" refers to the amount of information encoded with each pixel. Each pixel contains an 8-bit number that references one of the entries in the color table.


Preparing the Capture File

Before capturing video sequences, you must identify a capture file. The capture file sets aside an area of your hard disk to receive captured video and audio data. By ensuring that the capture file exists in a contiguous area on your hard disk, you can allow the highest possible disk-write speeds and reduce the chances of losing data due to disk seeks.

When creating a capture file, specify a size large enough to hold the entire video sequence. If you run out of room while capturing, VidCon32 will attempt to enlarge the file to hold the captured data. However, enlarging a capture file might cause the file to become fragmented and might also cause one or more frames to be dropped.

Hint You can use a capture file multiple times; when you finish capturing video, just save the video sequence to a different filename. You can also set aside multiple capture files.

To set the capture file

1	From the File menu, choose Set Capture File.
2	Type a filename for the capture file.
3	To specify the size of a new capture file, or to change the size of an existing file, type a size in megabytes, and choose OK.
4	From the Set Capture File dialog box, choose OK.

Defragmenting the Capture File

After allocating a capture file, you should use a disk-defragmentation utility to defragment the hard disk on which the capture file is stored. If the capture file does not reside in contiguous sectors of your hard disk, your system will be forced to perform a disk seek during the capture session, which might result in dropped video or audio data.

To defragment the hard disk, you can use a disk defragmentation application, such as the Defrag utility included with MS-DOS version 6.0.

Example of Capture-File Size

The following sample-video sequence would require approximately 23 megabytes of disk space:

Attribute	Value
Length	1 minute
Compression	None
Color format	8 bits per pixel (using a palette)
Frame size	160-by-120 pixels
Frame rate	15 frames per second
Audio format	8-bit samples, mono, 11.025 kHz sampling rate


contiguous

Residing within a single unbroken area of the disk. Hard disks are organized into sectors of data. A file might be stored across many sectors, and those sectors can reside in different areas of the hard disk. Because seeking to a different sector can take time away from the capture session, resulting in data loss, it's important to defragment the hard disk before capturing. This ensures the capture file resides in a contiguous area of the hard disk.


fragmented

Residing on non-contiguous sectors of the hard disk. When a fragmented file is written or read, the computer must skip to different areas of the hard disk to access the sectors making up the file. Seeking to a different sector takes time and can result in the loss of incoming video data.


dropped frames

Data lost during video capture. When capturing video, the system might notay be unable to finish processing the current video frame before receiving the next video frame from the source device. The incoming frame is ignored, or dropped, and a blank frame is stored in its place.


Setting Audio Options

Audio options determine the quality and storage requirements of the audio for your video sequence. Higher-quality audio takes more storage space, so you'll have to decide on an appropriate mixture of settings.

Audio formats range from the equivalent of a voice-grade telephone line (8-bit samples, mono channel, and 11.025 kHz frequency) to audio-CD quality (16-bit samples, stereo channels, and 44.100 kHz frequency). To capture audio with the video, you must have the audio sources connected to the audio-input ports on your audio card.

Hint If you work with multiple input sources, use a mixing board to select among the sources.

 To set the audio-data track format and sample rate

1	From the Options menu, choose Audio Setup.
2	Select the appropriate audio options. For information about the settings, see Audio Format Dialog Box .
3	Choose OK.

To set the maximum recording level of the audio input

1	From the Audio Format dialog box, choose the Level button.
2	While observing the volume bar, adjust the audio source so the volume peaks at about 80% of the full range shown on the volume bar.
3	Choose OK.


sample size

The amount of storage space used for each digitized portion of the audio track. Larger sample sizes provide greater dynamic range and, therefore, better audio reproduction (, but they require more storage space).


mono (monaural audio)

Audio format in which a single channel is used. Monaural audio requires half the storage space as stereo audio, which uses two channels of audio information.


sampling frequency

The rate at which digital- audio samples are taken. Higher sampling frequencies provide better fidelity but require more storage space.


stereo (audio)

Audio format in which two channels are used. Stereo audio can provide better sound reproduction but it requires twice the storage space as monaural (mono) audio.


Audio Format Dialog Box

The Audio Format dialog box lets you select the following audio settings, which determine the quality and storage requirements for the audio track:

Option	Description
Sample Size	Defines the amount of storage used for each digitized portion of the waveform. 8-bit samples use less memory to store waveform information; 16-bit samples provide greater dynamic range.
Channels	Specifies how many audio channels to use. Mono  waveforms store audio information in a single audio track. Stereo  waveforms use two tracks to store waveform information and double the amount of audio information per frame .
Frequency	Defines the rate at which audio samples are taken. The 11.025 kHz frequency (roughly equivalent to a voice-grade telephone line) samples over 11,000 samples per second. The 22.05 kHz frequency (equivalent in quality to AM radio) obtains samples twice as often as 11.025 kHz frequency. The 44.1 kHz frequency is the sampling rate used for audio CDs.
OK	Saves the audio settings.
Cancel	Closes the Change Audio Format dialog box without saving the audio settings.


Setting Video Options

You can choose the frame size and color format for the video sequence. Larger frame sizes provide greater impact but require more storage space. Video sequences can use an 8-bit color format with palette; this format plays on the widest variety of video displays and requires the least storage space. You can also use 16- or 24-bit formats  that preserve the original colors, but might also require three times the storage space.

The specific video-format options depend on the capabilities of the capture board. In addition to the frame-size and color-format options, some capture boards offer hardware-based compression routines that you select while choosing video options.

 To set the video options

1	From the Options menu, choose Video Format.
2	Select the appropriate size and color-format options. For information about the options, see Video Format Dialog Box.
3	Choose OK.


16- and 24-bit color formats

Video for Windows color formats that store color information directly with the pixel (rather than in a separate color table, as is used with the 8-bit format). This means there is no limit to the number of unique colors within a video frame.The 16- and 24-bit formats are called true-color formats because they preserve more of the original colors of the video signal. The 16-bit format provides a range of 32,767 color choices per pixel;, while the 24-bit format provides a range of 16 million color choices per pixel.


Setting Compression Options

You might be able to use software-based compression routines to compress the audio and video data during the actual capture session. When performing a step-frame capture (one frame at a time), your system has enough time to compress the current frame before processing the incoming data for the next frame. However, it's unlikely that your system will be able to perform software compression during a real-time capture, when the video source is playing at normal speed.

The specific compression routines provided by VidCon32 depend on the capabilities of the capture board  and on the compressors installed on your system.

Note If your capture boards supports hardware-based compression schemes that can be used during capture, select those schemes from the Video Format dialog box. For information about selecting video-format options, see Setting Video Options.

To set compression options

1	From the Options menu, choose Video Compression.
2	Select the compression options. For information about the options, see Video Compression Dialog Box.
3	Choose OK.


Video Format Dialog Box

Use this dialog box to select the video characteristics of the captured video sequence. These characteristics include the frame size and color format. Because the capabilities of capture boards vary, the contents of this dialog box depend vary among different capture boards. For information about the options, see the documentation for your capture board.


Video Compression Dialog Box

This dialog box lets you specify software compression techniques to apply during a capture session. Because software compression requires processing time, it's generally inappropriate to use during a real-time capture, except at very slow frame rates. You can, however, use software compression during a step-frame capture.

Note The RLE compression method, which requires similar processing time during capture and playback, is the only one usable during real-time capture.

Some capture boards  provide hardware-based compression that can be used during capture; however, these compression schemes are specified in the Video Format dialog box, not in this dialog box.

The contents of this dialog box are dependent on the video formats supplied by your capture board.


frame rate

The number of frames recorded for each second of video playback. Higher frame rates can provide smoother motion than lower frame rates.


step-frame capture

With step-frame capture, you capture video one frame at a time, generally from a paused source device. You capture a frame, advance the source device to the next frame, and then capture the next frame. Step-frame capture provides an alternative if your computer system cannot capture in real time without losing data. Step-frame capture also lets you increase the frame size, use a larger color format, or perform software compression (because, since the system has more time to store the captured data).


Setting the Palette

Two main color models are available for video sequences:

An 8-bit color model  that's compatible with the majority of video adapters. With 8-bit color, all the colors for a video frame are stored in a palette, a table of color values. Individual pixels within the video frame reference the entries in the table. An 8-bit palette can contain a maximum of 256 color entries, so you're limited to 256 colors per video frame. A video sequence can have multiple palettes, but switching from one palette to the next can cause undesirable color effects during playback.

16- or 24-bit color models  that preserve more of the original colors from the video signal but require at least two to three times more storage space. A 16- or 24-bit video sequence will show significant color changes when played back on common 8-bit video adapters.

When capturing video using the 8-bit (palette) format, VidCon32 uses a single palette for all video frames. Some capture drivers provide a 64-shade gray-scale palette, but you can supply a custom color palette compatible with the colors used in the video signal.

Applying an 8-Bit Palette to a Video Sequence

There are two ways to supply a palette for use in a video sequence:

Load a palette from a palette (.PAL) file. For example, you might create a standard palette for use in several video sequences; you can save this palette as a .PAL file and then use it whenever you capture video.

Use VidCon32 to create a palette from one or more frames of the video sequence. This approach lets you build a custom palette using the most-common colors in the video sequence. Once you create a palette from the video sequence, you can save it for later use with other sequences.

Be sure to experiment with different palettes before finalizing your video sequences. The right palette can dramatically improve the quality of your video sequence.

To build a palette from one or more frames

1	From the Capture menu, choose Palette.
2	Type the number of colors you want for the palette. You can type the following values:
Value	Description
1 through 236	Builds a palette with the specified number of entries. Larger numbers of entries provide more color choices, while smaller values can result in substantial reductions in file sizes after compression.
256	Builds an identity palette , with 236 colors defined from the incoming video signal, and 20 system-defined colors. Identity palettes provide more efficient processing during playback.
3	Choose from the following actions:
TO	Do This
Capture colors from a single frame	Choose the Frame button each time you want to capture colors from an image.
Start capturing colors from multiple frames	Choose the Start button to start capturing.
If the palette is for a video sequence, include several frames of data in the sequence from which you build your palette. By capturing colors from several frames, you provide a better representation of colors for the video sequence.

4	Choose the Close button.
There will be a slight delay while VidCon32 creates an optimal palette from the captured frames.

 To save a palette

1	From the File menu, choose Save Palette.
2	Select the filename for the palette (.PAL) file.
3	Choose OK.
Note If you haven't created a palette from the video sequence (as described in the preceding procedure), the video-capture driver will supply a default palette. This palette might be a color or gray-scale palette, depending on the capabilities of the capture driver.

To load a palette from an external file

1	From the File menu, choose Load Palette.
2	Select a palette (.PAL) file.
3	Choose OK.
There is a short delay while VidCon32 loads the new palette.


pixels

A single dot, or unit, within the computer display. The display is made up of a grid of pixels, each of which has its own color value.


identity palette

A palette containing the standard system colors arranged in a specific location (the top ten and bottom ten cells of the color table). An identity palette can be processed more quickly by Windows and can therefore provide improved display performance over a standard palette.


Testing the Setup

After configuring your video-capture settings, you can capture a single frame and display it in the VidCap display area. If your capture board  has overlay capabilities, be sure to set the VidCap frame display to show the capture preview rather than the overlay (from the Options menu, choose Preview Video).

If you're using the 8-bit (palette) color format, you should also determine whether your color palette is compatible with other images you plan to display in your presentation. Systems with 8-bit video adapters can display a maximum of 256 colors simultaneously. If two video sequences (or a video sequence and an image) use completely different colors, the system will be unable to display correct colors for both images simultaneously.

The video sequence in the active application will have priority for palette entries, so examine the inactive video sequence to see if any color changes occur. Whenever you display multiple images together on an 8-bit video display, it's a good idea to build composite palettes that contain the necessary color entries for all the images. Using composite palettes can prevent unexpected color changes during your presentation.


About the Capture Process

You can capture video sequences  manually or automatically using VidCap. In either case, the captured video and audio data is stored in a pre-allocated capture file  on your hard disk. Before starting video capture, you should create a capture file and set all the necessary options for the video sequence; for an overview of this process, see Setting Up for Video Capture.

You should consider the following techniques for capturing video:

Manual (step-frame) capture: With manual capture, you advance the source device frame-by-frame to display the necessary video images. Whenever a desired image is displayed, you capture the frame. This is a useful technique for capturing individual still images from a video source.

Automatic capture: With automatic capture, you capture a stream of video played at normal speed from the source device. During automatic capture, VidCap captures frames at the specified frame rate, storing the data in the capture file. Automatic capture can place high demands on your system because the hard disk needs to keep up with the incoming video and audio data. Be sure to use a fast computer with a fast hard disk, and prepare a defragmented capture file before beginning the capture process.

Automatic capture, with Vidcap controlling the source device: If your source device (videodisc player or videocassette recorder) includes a Media Control Interface (MCI)  device for controlling playback, VidCap can issue commands to position and play the device during the capture session. On videodisc players, you can also perform a step-frame capture, in which frames are advanced and captured at low speed, allowing a larger frame size and color format.

Capturing a Video Sequence Manually

You can capture a video sequence manually, one frame at a time. Frames are captured to the file you specified (for information about specifying a capture file, see Preparing the Capture File). After capturing a series of frames, you can save the video sequence to a different filename.

To capture frames manually

1	From the Capture menu, choose Capture Frames.
2	Start the video-source device.
3	Each time the first frame you want to capture is displayed on the output monitor, choose the Capture button on the Capture Frames dialog box.
4	When you finish capturing frames, choose the Close button, or press the ESC key.

You can capture a video sequence by a click on the record button described in VidCon32 Toolbar and Controls .


Capturing a Video Sequence Automatically

You can capture a series of frames automatically. In an automatic capture you capture the sequence to the capture file according to your specification of the attributes you made before (for information about specifying a capture file, see Preparing the Capture File). After capturing a series of frames, you can save the video sequence to a different filename.

When capturing video, you can control your video source in the following ways:

Manually (using the controls on the camera, videodisc player, or videocassette recorder).

Automatically, using a Media Control Interface (MCI) driver. With MCI control, you can specify the starting and ending points for the playback, and VidCap plays the specified segment automatically when you start capturing.

With either method, you begin by specifying a series of attributes for the video sequence. You then start the capture. You can capture for a preset period of time (for example, capture 3 minutes of video), or you can stop capture by pressing the ESC key.

Note During capture, your hard disk might not keep up with the frame rate you specified. If this occurs, VidCap inserts blank frames where it is unable to store frame data. When the capture session is complete, VidCap reports the number of blank or dropped frames. Dropped frames use minimal storage space (8 bytes) and do not adversely affect audio/video synchronization.

To capture a series of frames automatically

	From the Capture menu, choose Video.
	Select the recording options you want for the capture session. For information about the audio-recording format (available from the Audio button), see Audio Format Dialog Box. For information about the video-recording format (available from the Video button), see Video Format Dialog Box.
	If you're manually controlling your source device, start your source device.
	To start capturing frames, choose OK.
	To end capture, press the ESC key.


CaptureSetup menu

Command	Description
Capture directly to disk	For large video clips the best results are achieved by selecting the Directly to disk  option.
Capture to memory	If you want to capture very short sequences select this setting
Enable capture time limit	Enable a limit for overall capture time
Frame rate	Defines the number of digitized frames per second (frame rate )
Compression	Opens the video compression dialog box
Video Format	Sets the dimensions and color format of captured images.
Audio Format	Sets characteristics for the audio track of the video sequence.