[MEncoder-users] A/V sync issues with separately encoded streams

[Nicolas George]

Le quintidi 5 prairial, an CCXVII, Andrew Berg a écrit :
> Is there a way to get MEncoder to use the audio stream to keep the video
> on track, but output only the raw h264 stream and discard the audio?

DVDs are especially bad with your problem: at each place where a montage is
done between different streams (for example, between the opening of a series
and the actual episode), you can have more audio than video or more video
than audio. If you encode them separately, mencoder will encode everything
it has in the channel it is encoding. If you encode both audio and video, it
will drop or duplicate frames to keep in sync.

To encode separately, I used two solutions:

	-oac lavc -lavcopts abitrate=32

The encoding time is negligible compared to x264, and the size taken in the
output file is really small also. Surprisingly, the output AVI file has
completely wrong audio timestamps, but remuxing just the video works fine.

	-oac pcm -of rawvideo

mencoder decodes the audio, encodes it in the trivial codec, and then
ignores it. The resulting elementary H.264 stream can be muxed, it seems to
work. I only used this technique recently, I do not know if it is completely
reliable.

Regards,

-- 
  Nicolas George
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