Microsoft KB Archive/92757

= VFW: Troubleshooting - Frames Dropping During Playback =

Article ID: 92757

Article Last Modified on 10/14/2003

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APPLIES TO


 * Microsoft Windows Sound System 1.0
 * Microsoft Windows Sound System 1.0a

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This article was previously published under Q92757



SUMMARY
When playing an AVI file from Microsoft Video for Windows VidEdit, the file may not run smoothly due to the &quot;dropping&quot; of frames during file playback. The dropping of frames occurs when the time required for a frame's data to stream through the processor exceeds the real time the frame represents during playback. VidEdit attempts to compensate for this time difference by dropping frames to &quot;catch-up&quot; to the appropriate real time position.

NOTE: An AVI file may not play back as smoothly under VidEdit as it will using Media Player, which is designed to provide optimum playback for AVI files.



MORE INFORMATION
There are several steps that can enhance the performance obtained when playing AVI files from VidEdit. These steps are described below:


 * 1) If the AVI file is located on a CD, ensure that the CD-ROM drive is MPC compliant and can sustain a minimum data transfer rate of 150 K/Sec.
 * 2) If the AVI file is located on a hard drive, ensure that the AVI file is stored in a continuous region by running a defragmentation utility such as Norton Speed Disk. This will enhance playback by reducing the seek time required to access the file.
 * 3) Load a portion of the file into memory. VidEdit sets aside a segment of memory (a memory &quot;cache&quot;) to store audio and video-frame data. By loading part of a video sequence into this cache you can speed up most VidEdit operations. The size of this cache may be increased by choosing the Preferences option from the Edit menu in VidEdit and entering a new cache value into the Memory For Caching Images box. Keep the size of the cache smaller than the amount of physical memory on the machine; otherwise, portions of the cache might be swapped to disk, eliminating any speed improvements.
 * 4) Load the entire AVI file into memory. This can be done by choosing the Load File Into Memory command found on the Video menu in VidEdit. When using this option, virtual memory should be temporarily set to zero so that only true RAM is used. It should also be noted that the size of an AVI file may show a significant increase in size when decompressed, hence, attempting to load what appears as a relatively small AVI file into memory may not work, even on a machine with extensive RAM available.
 * 5) Select Fast Frame Update from the View menu in VidEdit. This option will lay data for the current frame over the previously-displayed frame in a manner that simply updates any changes that have occurred from one frame to another. Selecting this option may decrease the time required to process frame thus decreasing or eliminating the dropping of frames.

Additional query words: tshoot 1.00

Keywords: KB92757

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