[FFmpeg-user] Interlaced avi h264 to mp4

pssturges pssturges at gmail.com
Wed Jul 6 01:12:43 CEST 2011

Andrew Berg wrote:
> Sounds like they're 25fps and there are glitches that throw sync off.
> Demux it with tsMuxeR (or load the raw video stream with it), making
> sure "Add picture timing info" and "Continually insert SPS/PPS" are
> checked (I'm not sure where you can get tsMuxeR if you don't already
> have it, though; the official website has no links to it anymore). I
> always run my newly encoded video streams through it just in case there
> were glitches in the source since it has fixed sync issues on several
> occasions.
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I think that something like that is definately happening. I tried your
suggestion using tsmuxer and it made no significant difference.

Comparing the mediainfo output on the files produced by ffmpeg to those
produced by mp4box showed one significant difference. The ffmpeg files were
constant framerate and the mp4box files were variable framerate. A bit more
research on the gpac website showed that mp4box sometimes creates variable
frame rate videos if the source was avi. Using the nodrop option forces
constant framerate. Audio was still out of sync using this option. When I
use the nodrop option with my calculated framerate, sync is very close but
still not quite right. The calculated frame rates are in the order of

So at this point both methods (ffmpeg and mp4box) are very close. Ffmpeg has
motion issues but audio sync is good. Mp4box has good motion but audio sync
is still not quite right. My preference is to use ffmpeg because it is one
simple command. Using mp4box requires several steps including making some

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