[MEncoder-users] Audio / Video Sync issue

Raimund Berger raimund.berger at gmail.com
Sat Jun 7 18:37:15 CEST 2008


James Hastings-Trew <jimht at shaw.ca> writes:

>> You must be joking. From film/tv to DVD production, all sources and
>> intermediates contain accurate timing info. This includes his source
>> material, considering that mpeg2 is clock synced. And now he should
>> start guessing delays? Wow ...
> The audio on a DVD does not necessarily start at the same time as the 
> video. Users of such Windows tools as DGIndex know this, as it puts the 
> audio delay value right in the name of the audio tracks are they are 
> demuxed. So no, no need to GUESS the delay, just a matter of determining 
> what the delay value is.

Sure there can be 'delays', in case there are video frames and no
corresponding audio samples at whatever clock times in the stream. And
vice versa, of course.

OP implicitly knew that already though, has he experienced async on
remux. I guess he wanted to know how to fix that though, and telling
him to
 * use the delay option
 * find out how large the delay might be
isn't very helpful at all I'd say.

Helpful would be "find the value of a possible delay in the source
stream by xy means and then apply that with the delay option on
remuxing".

There may even be alternative options, like automagically including
silence or whatever. The mpeg stream demuxer has the knowledge after
all, might give some hint or even assist in fixing this.




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