[FFmpeg-user] Interlaced avi h264 to mp4

[Andrew Berg]

On 2011.07.05 05:54 AM, pssturges wrote:
> I have tried
> demuxing and remuxing with mp4box and the video plays perfectly on both the
> ipad and xbmc, but the audio is always out of sync.
Are you sure you set the right fps value? MP4Box assumes 25fps if you
don't specify (you might need 50fps). MP4Box doesn't typically give me
issues, but then again, I don't think I've ever tried to mux an
interlaced stream with it.
> Firstly, is there a way to confirm if the videos are in fact, interlaced?
MediaInfo.
> 'My Theory'
> My thought at the moment is that there should be some sort of flag in the
> MP4 container or the video stream specifying that the video is interlaced so
> that the player knows to handle it correctly. I suspect at the moment this
> flag isn't being set correctly. Does this sound like it could be the issue?
There isn't much reason for a container to hold this information. The
video stream itself has this flag.
> If this is the problem, can it be corrected during the conversion or after
> by modifying the mp4?
It just sounds like the video is interlaced. Hardware players (like the
iPad) can act really weird when they get something they don't expect.
Could be the people who wrote the iPad's video player decided interlaced
AVC was too uncommon and decided not to implement deinterlacing for AVC.
Sounds odd, but you'd be surprised how many hardware players support
certain compression standards and certain containers, but only certain
combinations.