[MPlayer-users] mencoder a-v sync and DVDs (again)

[Corey Hickey]

Robert R. Wal wrote:
> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
> On 03.02.11 Arpi pressed the following keys:
> 
> 
>>is this the same problem as with mplayer before, that constant 200-300ms
>>(sometimes random, change per chapter) delay?
>>i thought the demuxer fix solved it for both mplayer and mencoder...
> 
> 
> Nom this is really a problem with DVD mastering. Audio and Video almost
> never start at the same time, the difference is what was reported by our
> vstrip test some months before.
> 
> It is totally independent from the 200-300ms delay you've already
> handled. I mean, back when mplayer didn't solve this huge (~250ms) delay
> properly, mencoder showed only this <80ms difference which I handled
> with ogmmerge when muxing OGM. ogmmerge can quite preciselly cut/pad
> with silence AC3, Vorbis, PCM and MP3 sound.
> 
> This difference AFAIR is rougly difference between PTS of first audio
> and video frame.
> 
> Robert
> 

So, if I understand you correctly, mencoder and mplayer handle this in
two different ways:

Mplayer synchonizes audio and video based on the timestamps within each
stream. At any given point, the positions within each stream may differ
relative to the start of the stream.

Mencoder muxes audio and video from the beginning of each stream. Each
stream's position relative to its beginning is always the same.

Am I on track here? Does this mean that mencoder ought to pad/trim the
audio slightly so that the muxing starts off with audio and video in
sync?

-Corey