[FFmpeg-user] Interlaced avi h264 to mp4

pssturges pssturges at gmail.com
Tue Jul 5 14:26:22 CEST 2011

My original encoding of these avi's definitely has some issues. As I said
they play fine, but it's definately causing problems for me now. Every tool
I use, says they are 29.97 fps. XBMC plays them @ 25 fps and the audio stays
in sync. If I remux them at 25fps sync varies anything up to a few seconds.
If I mux them at 29.97 sync is WAY out. After demuxing the streams, closer
examination shows that the duration of the streams can be anything up to 6
seconds different. I tried doing calculations based on the total number of
frames of the video and also the duration of the audio to come up with a new
framerate figure and muxed using that. Audio would be in sync for parts but
not others. I have also tried adding delay. All of this done with mp4box.
And always the audio would not sync, but the video always played correctly
on the ipad.

If the flag is held in the stream not the container, then it seems mp4box is
setting it and ffmpeg is not (at least with the command as I have it). 

I have read, but not confirmed that ipad does not handle interlacing. It's
handling my mp4boxed video so I'm still not 100% certain that interlacing is
the problem.

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