Computer Shopper 242

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<lina:for-each name="/dialog-docs/dialog"> <lina:tag name="lina:create"> <lina:attrib name="file"><lina:arg name="filename"/></lina:attrib> <lina:attrib name="title">Dialogs: <lina:arg name="name"/></lina:attrib> <lina:body/> </lina:tag> </lina:for-each> <lina:data> <dialog-docs> <dialog name="Video filters" filename="d-videofilters.html"> <blockquote> <lina:image src="pics/d-videofilters.png"/> </blockquote> <ul> <li><a href="video-filters.html">Video filter reference</a></li> </ul> Video filters transform video frames sequentially, such as blurring the image, resizing the image frame, or applying noise reduction. VirtualDub's video filter system takes chains of filters, which are set up through the Video Filters dialog. <dl> <lina:dt>Frame sizes</lina:dt> <dd> Each video filter in the list is shown with the size of the video frame entering the filter and the video frame size produced by that filter. Video filter chains may be created without a video loaded, and when the video is changed, the input and output frame sizes for each frame will change accordingly. <lina:note> If no video is loaded, VirtualDub will compute frame sizes as if a 320x240 input were present. </lina:note> </dd> <lina:dt>Filter name and parameters</lina:dt> <dd> Each filter entry has the name of the filter beside the frame sizes, as well as a parameter list for the filter. The parameter list is filter-specific and is only shown to aid in scanning the filter chain. </dd> <lina:dt>Cropping</lina:dt> <dd> Cropping can be applied at the beginning of any filter by selecting the entry and selecting the Cropping... button. Once cropping borders are set, the cropped frame is reflected in the input frame size for that filter entry. <lina:note> The post-crop width and height should never be zero or negative. </lina:note> </dd> <lina:dt>Filter order</lina:dt> <dd> Filters are executed from top to bottom; use the Move Up and Move Down buttons move the currently selected filter up or down one slot. Frame sizes are automatically recomputed as filters are moved. </dd> <lina:dt>Loading filters</lina:dt> <dd> The Add Filters sub-dialog has a Load... button for loading third-party video filters. These video filters need to be written specifically for VirtualDub and have a <tt>.vdf</tt> file extension. <lina:note> Video filters loaded from this dialog are loaded only for the current session. If you want filters loaded all the time, move them under <tt>plugins\</tt> in VirtualDub's program directory. </lina:note> </dd> </dl> </dialog> <dialog name="Video frame rate control" filename="d-videoframerate.html"> <blockquote> <lina:image src="pics/d-videoframerate.png"/> </blockquote> The Video frame rate control dialog allows you to alter the frame rate of video, reduce the number of frames, or remove 3:2 pulldown. <dl> <dt>Adjusting frame rate</dt> <dd> If the source video has the wrong frame rate or doesn't natively have a frame rate (image sequence), you can specify one in the source correction portion of the dialog. You can either type in a rate, or have VirtualDub automatically choose a "same length" setting, such that the video and audio tracks end at the same time. <lina:note> No frames are added or deleted by this setting, so if the video is synchronized with the audio beforehand it won't be after you change the frame rate. Similarly, if the video isn't synchronized, you may be able to fix it with this setting. </lina:note> <lina:note> Manually entered frame rates are rounded to the nearest microsecond period. In particular, you cannot enter an exact NTSC fraction (30000/1001). </lina:note> </dd> <dt>Frame rate decimation</dt> <dd> Decimation pulls frames from a source at regular intervals. This is useful for producing "thumbnail" videos with small sizes, and for dropping the rate of a video without introducing jerkiness due to uneven frame rate. The decimation interval must be a positive integer. </dd> <dt>Inverse telecine (3:2 pulldown)</dt> <dd> 3:2 pulldown, or telecine, is the process by which film-rate material (24 fps) is converted to NTSC rate (29.97 fps). This is done by splitting the film frames into fields, and then "pulling" fields down in an alternating 3,2,3,2... pattern. This produces five output frames for every four input frames, in a characteristic pattern of three progressive frames, followed by two interlaced frames. The resultant 30 fps stream is then slowed down slightly to the target 29.97 fps. Inverse telecine (IVTC) attempts to recover the original 24 fps stream by analyzing the input frames and removing the duplicate fields. In adaptive mode, VirtualDub attempts to guess the position of the 3:2 pattern, while in manual mode, you specify the offset and polarity. In both cases, the input frame rate is dropped by 20%, changing a 29.97 fps input to 23.976 fps. The third mode, reconstruct from blurred fields, handles the case where a video has been telecined, and then the fields blurred together, usually by shrinking the video size. In this case the original frames cannot be recovered by matching fields, but can be recovered through simple frame algebra. The reconstructed frames will have more noise and possibly ghosting where clipping at black or white has occurred, but if successful the result is a smooth progressive video. <lina:note> All of VirtualDub's IVTC modes assume a regular 3-2 pattern. More complex telecine patterns are possible which cannot be removed through this system. </lina:note> </dd> </dl> </dialog> <dialog name="Video color depth" filename="d-videocolordepth.html"> <blockquote> <lina:image src="pics/d-videocolordepth.png"/> </blockquote> Selects the desired image formats for video decompression and video compression. <dl> <dt>Decompression format</dt> <dd> Selects a color format to target when decompressing the input video. For a compressed source, this format is requested directly from the video codec. "Autoselect" will choose a common, safe RGB format, such as 24-bit, 32-bit, or 15-bit RGB. For an uncompressed source (or Avisynth script), the desired format is produced through image conversion if it is not the same as the source. YCbCr-to-YCbCr conversions do not round-trip through RGB. "Autoselect" chooses the source format so that no conversion is necessary. If the video codec cannot produce the format you have selected, VirtualDub will automatically attempt to degrade the video format to a similar format that is supported. For instance, if 16-bit RGB fails, 24-bit RGB will be tried. The fallback code avoids color space conversions if possible; if a YCbCr format fails, other YCbCr formats will be tested before resorting to RGB. </dd> <dt>Output format</dt> <dd> Selects a color format for output. During preview, this is the format sent to the display panes. When video compression is active, this selects the format received by the video compressor. The output format is produced by conversion from the input format. When video filters are in use, the input format is converted to 32-bit RGB, processed, and the result converted to the output format. If video filters are not being used, the input format is converted directly to the output format. <lina:note> As is standard in GDI bitmaps, the 32-bit format has a dummy alpha channel, used only for padding. VirtualDub cannot currently target a 32-bit format with meaningful alpha. </lina:note> <lina:note> The size of the output format doesn't necessarily relate to how well the output compresses through a video codec. For instance, converting from 24-bit RGB to 16-bit RGB can hinder compression, because it increases quantization noise (banding) in the image. </lina:note> </dd> </dl> <h2>Format descriptions</h2> <dl> <dt>16-bit RGB (555)</dt> <dd>This is a format with five bits per channel (32 levels) for each of red, green, and blue. It is a relatively low-precision format that is prone to some banding artifacts but is common on older video display hardware, as it is faster and consumes less memory than 24-bit RGB. This format is sometimes known as HiColor.</dd> <dt>16-bit RGB (565)</dt> <dd>This is a slightly improved version of 16-bit RGB (555), as it uses the unused bit to improve precision in green.</dd> <dt>24-bit RGB (888)</dt> <dd>This is a format with eight bits per channel (256 levels) for each of red, green, and blue. It is common for photographic images and is often known as TrueColor. This is the safest and most reliable format to use for video interchange.</dd> <dt>32-bit RGB (8888) (dummy alpha channel)</dt> <dd>This is similar to 24-bit RGB, except that it has an additional unused eight bits per pixel. Picture quality is identical to 24-bit, but the additional padding makes the pixels a more convenient size for computation. This format is sometimes slightly faster than 24-bit for processing, but should be avoided for storage as it wastes one-third more space.</dd> <dt>4:2:2 YCbCr (UYVY)</dt> <dd>This is a format which uses the YCbCr color space (luma, chroma-blue, chroma-red), which is closer to the way color images are perceived by the human brain. It averages only 16 bits per pixel with similar perceptual quality to 24-bit RGB by only storing color information at half horizontal resolution, producing slight color bleeding but only taking two-thirds as much space. This format, as do all other YCbCr formats listed below, encodes luminance (Y) with a range of [16, 235] and chroma (Cb/Cr, or U/V), with a range of [16, 240]. UYVY is accepted directly by many video codecs. Since many video codecs internally use color spaces similar to YCbCr, using this format with video codecs can speed up rendering. </dd> <dt>4:2:2 YCbCr (YUY2)</dt> <dd>This is the same as 4:2:2 YCbCr (UYVY), except for a shuffling of data bytes. It has the same quality and performance advantages as UYVY. </dd> <dt>4:2:0 planar YCbCr (YV12)</dt> <dd>This is a YCbCr format with an average of 12 bits per pixel and half resolution both horizontally and vertically in color information. It thus takes 25% less space than UYVY or YUY2, but with some vertical bleeding. "Planar" refers to the organization of data in the format, where luma, chroma-blue, and chroma-red are stored separately. Some codecs accept this format directly for further increases in performance over the 4:2:2 formats. However, it should be avoided for interlaced video, where the loss of vertical color resolution can cause motion artifacts between fields. <lina:note> Although 4:2:0 YCbCr formats exist that accommodate interlacing, the YV12 four-character code (FOURCC) denotes a specific 4:2:0 encoding that is non-interlaced. </lina:note> </dd> <dt>4:2:2 planar YCbCr (YV16)</dt> <dd>This is a YCbCr format with an average of 16 bits per pixel and half horizontal resolution in color information. The YV16 format is rare and not well supported by video codecs and playback applications, but is supported here for completeness. </dd> <dt>4:1:0 planar YCbCr (YVU9)</dt> <dd>This is a YCbCr format with an average of 9 bits per pixel and quarter resolution both horizontally and vertically in color information. YVU9 thus takes 43% less space than UYVY/YUY2 and 62% less space than 24-bit RGB, but at the cost of significant color bleeding. </dd> <dt>Luminance only (Y8)</dt> <dd>Y8 is a monochrome format, and thus selecting it will cause video to be converted to grayscale. However, it only requires half of the space of UYVY or YUY2 at 8 bits per pixel. Y8 uses the same luma scale as YCbCr, 16-240, so there is a very slight loss of luma precision compared to 24-bit RGB. However, conversion between Y8 and YCbCr formats is lossless in luma and extremely fast. </dd> </dl> </dialog> <dialog name="Video range" filename="d-videorange.html"> <blockquote> <lina:image src="pics/d-videorange.png"/> </blockquote> Selects a subset of the input to use. <dl> <dt>Input range</dt> <dd> Controls how much video at the beginning and ends of the source is skipped during processing, so that only a portion in the middle is used. All offsets can be set in either frames or milliseconds (ms). <lina:note> Offsets persist even if you load a new file. </lina:note> <lina:note> The end offset is the number of milliseconds from the end, not from the beginning. It is usually easier to set start/end points from the position control (HOME/END). </lina:note> <lina:note> You can only select a single range with this dialog; use the delete frames feature to extract multiple segments in a single pass. </lina:note> </dd> <dt>Offset audio to maintain a/v sync</dt> <dd> Controls whether the start offset applies to the audio stream. If unchecked, the start offset deletes frames only from the video stream, advancing it that many frames ahead of the audio stream. This will alter audio/video synchronization accordingly. </dd> <dt>Cut off audio when video stream ends</dt> <dd> If the audio stream is longer than the video stream, this controls whether the extra audio is used or not. Generally, players continue to show the last video frame while the remaining audio plays. </dd> </dl> </dialog> <dialog name="Video compression" filename="d-videocompression.html"> <blockquote> <lina:image src="pics/d-videocompression.png"/> </blockquote> VirtualDub can use video codecs installed in Windows to compress video. <lina:note> Video codecs are external drivers created by third parties and are not part of VirtualDub. VirtualDub does not install codecs by itself and does not provide any video compression technology of its own. </lina:note> <dl> <dt>Selecting a video codec</dt> <dd> Currently installed video codecs are listed in the top left pane; select a codec to use or choose "uncompressed RGB" to disable video compression. Once a codec is selected, diagnostic information appears on the right side. Every codec has a unique fourcc, or four character code, associated with it. <lina:note> Not all codecs are usable -- sometimes programs install versions of a codec designed only to decompress video, not to compress it. Also, sometimes the codecs are keyed to a particular program due to licensing concerns, and thus won't work in VirtualDub. </lina:note> <lina:note> For performance reasons, many codecs split the video frame into equal-size tiles and thus require the frame width and height to be specific multiples of the tile size. Requiring the width to be a multiple of four pixels is very common. VirtualDub attempts to detect such limitations and displays any such information in the right pane. In some rare cases with broken codecs this check fails, and the result may be a "bad format" error when you attempt to begin compression. </lina:note> </dd> <dt>Configuring the codec</dt> <dd> Some codecs accept quality, data rate, and key frame interval parameters. The higher the quality, generally the slower the codec runs and the larger the output, but the better the video looks after compression. By setting a data rate, you request that the codec attempt to produce output at a fixed size-per-time ratio, set in kilobytes/second. And by setting a key frame interval, you are enforcing that seek points are placed at regular intervals in the video in order to reduce wait time when seeking. Nearly all codecs support additional parameters, which can be set by pressing the Configure button. The dialog that appears is codec-specific; please consult the documentation for each codec for further details. <lina:note> Codecs are designed for a particular range of frame sizes and compression ratios and perform inefficiently outside that range. In particular, for most codecs, setting Quality to 100 is likely to produce ridiculous file sizes and may not even produce perfect-looking video. Small file size and perfect-quality video are mutually exclusive. If you need perfect quality and are willing to put up with large file sizes, lossless codecs exist that are created specifically for this purpose. </lina:note> <lina:note> If the codec allows you to enter a key frame interval but you don't enter one, you may get a video with a single key frame at the beginning. This means that every time you seek backwards in the video the player will have to decompress the entire video from the start up to that point, which is a tad slow. Key frames generally have lower compression ratios, so the interval determines a tradeoff between seek latency and compression efficacy. </lina:note> <lina:note> Data rates specified here only pertain to video. Make sure to allow for audio and for file structure overhead. </lina:note> <lina:note> Many modern codecs do adaptive key frame placement and more complex data rate regulation, and place all their settings in their configuration dialog. Although the data rate entry in VirtualDub's configuration dialog is specified in units of kilobytes per second, or 1024 bytes/sec, codec dialogs generally use kilobits per second (Kbits/sec), or 1000 bits/sec (125 bytes/sec). </lina:note> </dd> </dl> </dialog> <dialog name="Audio filters" filename="d-audiofilters.html"> <blockquote> <lina:image src="pics/d-audiofilters.png"/> </blockquote> <ul> <li><a href="audio-filters.html">Audio filter reference</a></li> </ul> VirtualDub's advanced audio filter mode supports a filter graph model, where you can chain filters in complex, branching configurations. Filters are represented by rectangular nodes on the graph; each node may have input pins on the left and output pins on the right. <dl> <dt>Adding and removing filter nodes</dt> <dd> To add filters, click the Add... button. This displays the Add filter subdialog, which displays a list of available filters. In that subdialog, click a filter entry and then Add to add the filter to the graph, or alternatively, double-click the filter entry. The subdialog stays up until you are done adding filters and close it. Filter nodes added by mistake can be removed by clicking on them and pressing the Delete key or button. </dd> <dt>Connecting filter nodes</dt> <dd> To connect filters together, drag from an input pin of one node to the output pin of another. (You cannot connect two input pins or two output pins.) An arrow will be displayed showing the connection. As with nodes, connections may be selected and deleted. Since this process is rather tedious, by default the auto-connect option is enabled. Auto-connect ties the first unused output pin of the currently selected filter to the first input pin of the newly added filter, and then selects the new filter. Simple chains can then be established just by adding the filters sequentially. </dd> <dt>Filter graph restrictions</dt> <dd> The following rules apply to audio filter graphs: <ul> <li>There must be exactly one "source" node.</li> <li>There must be exactly one "output" node.</li> <li>All pins must be connected.</li> <li>No cycles are allowed, although parallel branching is permitted.</li> <li>Parallel paths must run at the same speed.</li> </ul> The last rule means you can't take a stream, slow it down with "stretch", and then mix it back with itself. </dd> </dl> </dialog> <dialog name="Audio interleaving" filename="d-audiointerleaving.html"> <blockquote> <lina:image src="pics/d-audiointerleaving.png"/> </blockquote> Although video clips have simultaneous audio and video streams that play at the same time, the files that contain them are a single stream. Interleaving fakes having two streams by slicing the audio and video streams into chunks and mixing them together in chunks by time. A player reading an interleaved file receives a little bit of audio, then a bit of video, and then more audio, etc., buffering them in memory for a short time before playing the two together. VirtualDub's audio interleaving dialog controls how interleaving is performed. <lina:note> Audio interleaving has absolutely zero impact on when audio plays -- regardless of how audio and video frames are scattered in an AVI file, they still maintain the same timing relationship, because the index block sequences them properly. </lina:note> <lina:note> Interleaving audio and video is not necessary unless the file is stored on a medium that streams much more efficiently than it handles random access, such as a CD-ROM drive or transmission over the Internet. High-speed devices such as hard disks can handle playback from non-interleaved files without problem, which is a consideration as interleaving isn't free -- it costs a small amount of overhead in the file size. </lina:note> <dl> <dt>Enable audio/video interleaving</dt> <dd> If this option is selected, audio blocks are interleaved between video frames throughout the file. If not, all of the audio is placed at the end. </dd> <dt>Preload</dt> <dd> Players require a certain amount of audio to be buffered ahead of time before starting video playback. The preload option controls how much audio is placed at the beginning of the file before the first video frame, in milliseconds. Usual values for this are 500ms (half second) or 1000ms (full second). If this setting is improperly adjusted, the file may not play optimally on slow computers or slow devices, although with modern video players this is less of a concern. </dd> <dt>Interleave interval</dt> <dd> Controls how often audio blocks are scattered throughout the file -- the shorter the interval, the less buffering required by the player, but the more overhead in the output file. If the interleaving interval is too large, players will have to seek back in forth in the file, which has the worst of both worlds since the interleaving won't allow the player to do large, contiguous reads in the file. Usual values for this option are either interleave once per frame (1 frame) or every half second (500ms). </dd> <dt>Audio skew correction</dt> <dd> This isn't really an interleaving option, and is the only option here that actually does affect audio sync -- but it is here for lack of a better place. Audio delay basically shifts the audio track back and forth, either by dropping samples from the beginning or adding samples at the start (zero for PCM, duplicated first sample for compressed audio). Use this option to shift an audio track into place if it seems a bit off. <lina:note> Audio compression may impede use of delays. Some formats, particularly, ADPCM, use large block sizes that will limit the granularity of adjustments. The MP3 format used in AVI, on the other hand, has a hack in its format that prevents applications from seeing the "true" block size of the format. The result is generally junk produced at the beginning of the MP3 stream, which may not produce the desired delay depending on the player. An audio editor specifically designed to edit MPEG audio streams is required in these cases. </lina:note> </dd> </dl> </dialog> <dialog name="Audio compression" filename="d-audiocompression.html"> <blockquote> <lina:image src="pics/d-audiocompression.png"/> </blockquote> VirtualDub can use audio codecs installed in Windows to compress video. <lina:note> Audio codecs are external drivers created by third parties and are not part of VirtualDub. VirtualDub does not install codecs by itself and does not provide any audio compression technology of its own. </lina:note> <dl> <dt>Selecting a audio codec</dt> <dd> Currently installed audio codecs are listed on the left. Select No compression (PCM) to disable audio compression, or choose a codec. Once a codec is chosen, the available compression formats produced by the codec are shown on the right. By default, VirtualDub only displays those formats that can be produced by the codec from the current audio source and filtering settings. Uncheck show all formats to display all formats allowed by the codec, but note that attempting a conversion unsupported by the codec will generally result in an error. <lina:note> Not all codecs are usable -- sometimes programs install versions of a codec designed only to decompress audio, not to compress it. Also, sometimes the codecs are keyed to a particular program due to licensing concerns, and thus won't work in VirtualDub. In particular, codecs installed by some versions of Windows Media are not licensed for general use and won't work except for in an ASF file under Windows Media Player. </lina:note> <lina:note> Installing two codecs that compress and decompress the same format may confuse VirtualDub. This includes having more than one MP3 codec, or having both Windows Media Audio and "DivX Audio" installed. </lina:note> <lina:note> There are four common versions of the MPEG Layer-3 codec that appear the same, except for the compression formats supported: <ul> <li><tt>L3CODECX.ACM</tt> - no compression supported</li> <li><tt>L3CODECA.ACM</tt> (Advanced) - up to 56Kbps</li> <li><tt>L3CODECP.ACM</tt> (Professional) - up to 128Kbps</li> <li><tt>L3CODECP.ACM</tt> (Radium warez version) - up to 256Kbps</li> </ul> All four of these codecs are very similar and have the same ID in the Windows Audio Compression Manager, so two programs that come with different versions sometimes overwrite each others' codecs when installing. If you used to have certain MP3 compression options and no longer have them, it's possible a program you recently installed has done this. </lina:note> </dd> </dl> </dialog> <dialog name="Audio conversion" filename="d-audioconversion.html"> <blockquote> <lina:image src="pics/d-audioconversion.png"/> </blockquote> The audio conversion dialog allows for conversion between different PCM audio formats, including changes in sampling frequency, sample precision, and channels. <lina:note> Audio conversion is only permitted if advanced filtering is off -- if advanced audio filtering is on, use the resample filter. </lina:note> <dl> <dt>Sampling rate conversions</dt> <dd> Allows changes in the sampling rate of the audio stream, without changing the pitch of the audio itself (resampling). You can select one of the common sampling rates, or custom to resample to any other rate. Higher sampling rates represent higher frequencies better and give "brighter" audio, but consume more space. <dl> <dt>Integral conversion</dt> <dd> Forces the conversion to operate by integral multiplies (one-half, one-third, twice, three times, etc). Use this if you want to convert to a integral factor of the original rate that's close but not exactly the same as one of the listed values, i.e. 22047.5Hz. If the frequency you select is exactly what you want then this option should be unchecked. </dd> <dt>High quality</dt> <dd> Switches the resampling filter from point sampling to a triangle filter for better quality. This reduces aliasing, which sounds like noise or halo in the output. </dd> </dl> <lina:note> The sampling rate converter controlled by this dialog is rather antiquated and not very high-quality by today's standards. The resample filter introduced in VirtualDub 1.5 uses a 65-point windowed-sinc filter and produces better quality than the triangle filter allowed here. It is slated to replace this resampler as the primary resampler in a later version. </lina:note> </dd> <dt>Precision</dt> <dd> Controls the accuracy of audio samples -- 8-bit samples only take half as much space as 16-bit, but can't represent soft sounds as accurately and have a higher noise floor. <lina:note> 8-bit should really only be used if you are outputting uncompressed PCM to another program that needs it, or aren't changing existing 8-bit PCM. Otherwise, instinctually choose 16-bit. Modern audio codecs work in different audio representations, such as subbands or cosines, and thus don't get better compression with 8-bit source than with 16-bit. </lina:note> </dd> <dt>Channels</dt> <dd> Allows conversion of stereo audio to mono or mono to stereo. For stereo-to-mono conversions, the two channels are summed at half amplitude (<tt>(l+r)/2</tt>). For mono-to-stereo conversions, the single channel is replicated into the left and right outputs. The left and right options convert a stereo stream to mono by discarding the unwanted channel. This is particularly useful for some dual-language or karaoke produced, where two mono streams are stored as the left and right channels of a stereo track. <lina:note> For simple audio encodings such as PCM or ADPCM, dropping a stereo stream to mono halves the size of the audio stream. More complex encodings such as MP3, however, can encode a stereo stream as "center" and "side" tracks or volume differentials (mid/side and intensity modes of joint stereo). Such methods take advantage of similarities between the stereo channels and can make stereo relatively cheap to encode over mono. </lina:note> </dd> <dt>Bandwidth required</dt> <dd> Shows how much space would be required per second of audio without compression (uncompressed PCM), in kilobytes per second (KB/s). CD-quality audio, for instance, requires 172KB/sec (176,400 bytes per second). </dd> </dl> </dialog> <dialog name="Audio volume" filename="d-audiovolume.html"> <blockquote> <lina:image src="pics/d-audiovolume.png"/> </blockquote> Permits volume adjustments to audio, to make the audio louder or softer. <lina:note> VirtualDub hard clips when amplifying audio, so boosting the volume too much will result in distortion. </lina:note> <lina:note> It is easier to make soft audio louder than to make loud audio softer -- if the source audio was so loud that it clipped during recording, introducing distortion, reducing volume after the fact won't remove the distortion. On the other hand, amplifying soft audio also amplifies quantization noise, which is particularly bad with 8-bit source. Try not to adjust volume more than you need to; it is better to record audio at the right volume in the first place. </lina:note> </dialog> <dialog name="Capture settings" filename="d-capturesettings.html"> <blockquote> <lina:image src="pics/d-capturesettings.png"/> </blockquote> Controls basic video capture settings. <dl> <dt>Wait for OK to capture</dt> <dd>If checked, a dialog is displayed after capture is initialized. This minimizes click-to-capture delay.</dd> <dt>Frame rate</dt> <dd>Controls how fast video frames are captured. <lina:note>Frame rates are rounded to the nearest microsecond period.</lina:note> </dd> <dt>Round to nearest millisecond</dt> <dd> Some capture drivers only allow frame rates corresponding to integer periods in milliseconds. With such a driver, for instance, the two closest rates to 15 fps are 14.925 fps (67 ms) and 15.152 fps (66 ms). This button allows you to see the actual rate that would occur. </dd> </dl> <h2>Obsolete settings</h2> Many settings that used to be in this dialog have been obsoleted or moved: <dl> <dt>Capture audio</dt> <dd>Now an option on the Audio menu.</dd> <dt>Abort hotkey and button</dt> <dd> The abort hotkey is now always Esc. Also, it is program-local (VirtualDub must have focus for it to work). </dd> <dt>Audio and video buffer limits, audio buffer size</dt> <dd> Set automatically. </dd> <dt>Drop % limit, maximum index entries, lock video stream to audio</dt> <dd> These options applied only to AVICap (compatibility mode) capture, which is no longer supported. </dd> </dl> </dialog> <dialog name="Preferences" filename="d-preferences.html"> <blockquote> <lina:image src="pics/d-preferences.png"/> </blockquote> Sets application preferences. Main tab: <dl> <dt>Output color depth</dt> <dd> Selects the default color precision for video display -- 24-bit looks better, but 16-bit is generally faster. This does not affect file output. </dd> <dt>Process priority</dt> <dd> Force VirtualDub to be at a higher or lower priority than other applications when processing files. VirtualDub will always use CPU time that goes unused by other programs, but you can use this setting to force it to use more or less CPU when other applications need it as well. </dd> <dt>Automatically add extension to filenames when saving</dt> <dd> Controls whether file extensions (<tt>.avi</tt>) are automatically added when you type a filename without one in a save dialog. </dd> </dl> Display tab (none of these options affect file output): <dl> <dt>Enable 16-bit dithering</dt> <dd> If enabled, 24-bit images are dithered when displaying in 16-bit to reduce banding, at the cost of a little speed. </dd> <dt>Use DirectX for display panes</dt> <dd> Enables accelerated video display for the display panes. This usually results in much better display performance as well as a better looking, smoother (interpolated) image. Disabling this option forces use of the safest but slowest display mechanism, which uses Windows GDI to render video images. </dd> <dt>Use DirectX when Terminal Services is active</dt> <dd> Enables accelerated video display over a remote session using Windows Terminal Services or Remote Desktop. Due to apparent bugs in the Terminal Server implementation, allowing DirectX acceleration in this mode can cause video to always display in the upper-left corner of the desktop, so by default VirtualDub disables acceleration when it detects a remote session. This is often faster anyway. </dd> <dt>Use Direct3D</dt> <dd> Enables use of the Direct3D 9.0c accelerated 3D graphics API to display video. This enables use of the filtering options in the display panes to select between point sampling and bilinear filtering, and if the 3D device is powerful enough, bicubic filtering. </dd> <dt>Use effect file</dt> <dd> Enables use of a D3DX effect file (<tt>.fx</tt>) to specify custom Direct3D vertex and pixel shaders to display video. This requires an additional DirectX system DLL to be installed and knowledge of the effect file format to create the appropriate effects. Consult the <a href="fxvideo.html">video shader reference</a> for details. </dd> <dt>Use OpenGL</dt> <dd> Enables use of the OpenGL accelerated 3D graphics API to display video. This enables use of the filtering options in the display panes to select between point sampling and bilinear filtering. Note that use of OpenGL when an accelerated 3D device is not present may result in substantial performance degredation. </dd> </dl> Scene tab: <dl> <dt>Interframe (cut) and intraframe (fade) thresholds</dt> <dd> Controls the sensitivity of the scene forward/backward buttons on the position bar. A "scene change" is detected whenever there is a significant change in the image (cut), or scene details drop below a threshold (fade). </dd> </dl> CPU tab: <dl> <dt>Use default optimizations, or force specific optimizations</dt> <dd> By default, VirtualDub automatically detects your CPU and chooses appropriately optimized code paths. If you experience problems due to incorrect detection, you can force specific codepaths on or off in this tab. Note that enabling an optimization not supported by your CPU will result in a crash or incorrect execution. <lina:note> Video and audio codecs do their own CPU-specific dispatch, and are not controllable by these settings. If you experience problems with a codec that is not detecting your CPU correctly, you must contact the codec manufacturer for help. </lina:note> </dd> </dl> AVI tab: <dl> <dt>Restrict legacy AVI support to 1 gigabyte</dt> <dd> Extended AVI files (AVI 2.0 or OpenDML AVI) are composed of two parts: a legacy AVI portion, and extended AVI blocks. This option drops the limit for the legacy portion from 2GB to 1GB, for applications that cannot handle AVI files between 1-2GB, and may be helpful if you have running applications that scan AVI files and choke on large ones. It has no effect on programs that handle extended AVI files. </dd> <dt>Do not correct MPEG layer III audio streams</dt> <dd> Some MP3 codecs do not generate MP3 streams at exactly the same rate as specified in their audio format when 44.1KHz sampling rates are used -- this causes a small discrepancy in audio sync of around 0.5%. By default, VirtualDub recomputes the data rate and automatically corrects the audio header when MP3 compression is active. This option allows you to disable correction if it is causing problems, such as an MP3 stream being generated in a format that VirtualDub cannot parse correctly. </dd> <dt>Directly decode YCbCr (YUV) sources</dt> <dd> By default, VirtualDub will directly decode AVI video streams with uncompressed YCbCr formats that it recognizes, including UYVY, YUY2, YV16, YV12, I420, IYUV, Y41P, YVU9, Y8, and Y800, even if an external video codec would otherwise be used. This can result in better quality as VirtualDub uses bilinear interpolation when upsampling chroma. Disabling this option will disable YCbCr decode support and allow use of video codecs to handle such data. </dd> <dt>Align large uncompressed frames to sector boundary</dt> <dd> Some self-contained, professional-level hardware playback devices attain higher performance when working with AVIs that have video frames aligned to sector boundaries on the disk rather than the simple two-byte alignment required by AVI. Enabling this option causes sector alignment to be used, at the cost of slightly larger AVI files. The additional alignment is only in effect when a recognized uncompressed video format is used and the size of the video frame exceeds the specified threshold size. </dd> </dl> Timeline page: <dl> <dt>Timeline format</dt> <dd> This option allows customization of the timestamp indicator on VirtualDub's main UI. Formatting specifiers — a percent sign followed by a letter — cause various pieces of information to be substituted into the given string. The permitted formatting specifiers are listed below the editable string. </dd> </dl> Render options: <dl> <dt>Confirm when abort button is pressed</dt> <dd> When enabled, attempts to abort a preview or save operation will cause a confirmation dialog to be displayed before actually aborting. </dd> </dl> </dialog> </dialog-docs> </lina:data>