I was trying to compare quality results between AVC MP4 and DivX AVI and I encountered a weird anomaly. Renders with loop regions set to absolute frame positions produces output that starts and ends in different output frames for both video and audio!!! This scares me.
The results with Vegas Pro 9.0d:
DivX AVI video produced by Vegas duplicated the first frame of the loop region selected 4 times! And the audio led by 3 frames because of this!
AVC MP4 video produced by Vegas started the clip one frame before the start frame selected in the loop region but at least the audio was still in sync.
Cineform AVI video produced by Vegas seemed to output exactly the frames selected in the loop region with audio synced.
Strangely enough, if I took the outputted Cineform AVI and processed it to DivX within VirtualDub (rather than directly with Vegas), the correct frames are output with synced audio.
Vegas does not seem to output lossy video accurately! If audio sync needs to be frame accurate, don't output to DivX within Vegas.
The results with Vegas Pro 9.0d:
DivX AVI video produced by Vegas duplicated the first frame of the loop region selected 4 times! And the audio led by 3 frames because of this!
AVC MP4 video produced by Vegas started the clip one frame before the start frame selected in the loop region but at least the audio was still in sync.
Cineform AVI video produced by Vegas seemed to output exactly the frames selected in the loop region with audio synced.
Strangely enough, if I took the outputted Cineform AVI and processed it to DivX within VirtualDub (rather than directly with Vegas), the correct frames are output with synced audio.
Vegas does not seem to output lossy video accurately! If audio sync needs to be frame accurate, don't output to DivX within Vegas.