[Theora] Video and audio not in sync

Nils Pipenbrinck np at inverse-entertainment.de
Fri Jun 3 10:38:40 PDT 2005

Sal wrote:

 > Oddly, "ffmpeg2theora mencoder.avi" doesn't quite work. It generates
 > a .ogg file where the video starts a second after the audio, so the 
 > thing is out of sync right from the beginning. But "theora-encoder
 > mencoder.avi" (avi -> yuv -> example_encoder) works.

If I'm not mistaken ffmpeg has issues with AVI files that contain audio 
samples before the video frames. I haven't really tracked down the 
problem, but it seems that ffmpeg discards all audio frames that are 
stored before the first video frame (physical, in the file itself). The 
standard AVI multiplexer does this to allow some prebuffering for the 
audio stream. We just multiplexed the source AVI-files, disabled 
audio/video interleaving and the gap at the start was gone..

Nils (not on this list, but I read on the web interface every once in a 

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