[matroska-devel] Re: matroska AV sync?

Steve Lhomme steve.lhomme at free.fr
Mon Jan 27 16:18:32 CET 2003


En réponse à Pamel <paul at msn.com>:

> "Steve Lhomme" <steve.lhomme at free.fr> wrote
> > There is nothing like a timecode offset in the current specs (I just
> > checked to make sure). But it might be a good addition, even though
> you
> > would have to update it on the same track in different segments.
> 
> Doh!  This idea was originaly brought up by Christian, and somebody
> said
> they were going to add it, but I never bothered to check to see if it
> had
> been.  The idea was to add a field to the header that would offset all
> timecodes in a track by a given amount, that way you wouldn't have to
> rewrite the entire file when trying to obtain synch, you just change
> the
> value around until it is correct.

Yes, I remembered that. That's why I was a bit surprised that it wasn't there.
I'm just in the process of updating the specs with the recent discussions... And
actually that offset exists ! It's the DateUTC (information about a segement) :
"Date of the origin of timecode (value 0), ie production date". An EBML date is
"signed 64 bits integer in nanoseconds referring the beggining of the millennium
(2001/01/01 00:00:00.0000000 UTC)".

So don't worry, it was there already :)
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