[MEncoder-users] number of yuv4mpeg frames does not match audio length.

[Maarten de Boer]

Investigating a bit more, I found that if I play the audio separately,
A/V sync is much better, so I guess the A/V sync problem comes from the
MP4Boxing... I'll take it to the gpac mailinglist.

$ mplayer -vo null -ao pcm result.mp4 
$ (aplay audiodump.wav &) ; mplayer -ao null result.mp4 

maarten



On Wed, 21 May 2008 19:18:26 +0200
Maarten de Boer <mdeboer at iua.upf.edu> wrote:

> 
> Hello,
> 
> Sorry for crossposting, but the problem I describe occurs with all three
> applications, mplayer, mencoder and ffmpeg. I you respond for a specific
> application, please use the respective mailinglist only.
> 
> I am trying to convert a VOB file to h264+aac in an mp4 container (using
> x264, faac and MP4Box). I don't get the mp4 to be A/V sync (the
> material has some very obvious points). Investigating this problem, I
> found that the yuv4mpeg stream that I am using as input for x264 does
> not have the expected number of frames. As a reference, I look at the
> duration of the extracted audio:
> 
> mplayer -vo null -ao pcm test.vob
> 
> Duration    : 00:00:11.168
> 
> At my framerate of 29.97, this corresponds with 334.7 frames (not sure 
> whether to round this up or truncate it)
> 
> However this is what I get with:
> 
> mplayer -harddup -noframedrop -vo yuv4mpeg -ao null test.vob
> 
>   333 frames
> 
> mencoder test.vob -vf-add harddup -vf-add =i420 -ovc raw -of rawvideo -nosound -o mencoder.420
> 
>   333 frames
> 
> ffmpeg -i test.vob -f yuv4mpegpipe ffmpeg.yuv
> 
>   342 frames (starting with 1 totally green frame)
> 
> Especially the ffmpeg output is quite surprising. I guess the mplayer/mencoder
> output could be correct, and the sync problem is elsewhere, though this still
> doesn't account for the missing frame...
> 
> Any advice would be greatly appreciated!
> 
> Maarten
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