Re: [FFmpeg-devel] [PATCH 4/6] doc/muxers: add mkvtimestamp_v2

[Stefano Sabatini <stefasab@gmail.com>]

On date Tuesday 2024-04-16 12:50:19 +0200, Andreas Rheinhardt wrote:
> Stefano Sabatini:
> > ---
> >  doc/muxers.texi | 8 ++++++++
> >  1 file changed, 8 insertions(+)
> > 
> > diff --git a/doc/muxers.texi b/doc/muxers.texi
> > index f94513527d..490d5557bf 100644
> > --- a/doc/muxers.texi
> > +++ b/doc/muxers.texi
> > @@ -2933,6 +2933,14 @@ MicroDVD subtitle format muxer.
> >  
> >  This muxer accepts a single @samp{microdvd} subtitles stream.
> >  
> > +@section mkvtimestamp_v2
> > +mkvtoolnix v2 timecode format muxer.
> > +
> > +Write the PTS rawvideo frame to the output, as supported by the
> > +@command{mkvextact} tool from the @command{mkvtoolnix} suite.
> > +
> > +This muxer accepts a single @samp{rawvideo} stream.
> > +
> >  @section mp3
> >  
> >  The MP3 muxer writes a raw MP3 stream with the following optional features:
> 

> This is wrong: MKVToolNix switched to "# timestamp format v2" a long
> time ago (we still write the old "# timecode format v2" header);
> furthermore, MKVToolNix actually uses pts (which it reorders to be
> ascending), not dts like our muxer. Furthermore MKVToolNix does not
> force a 1ms precision on timestamps.

Correct.

I compared the output of the muxer and of mkvtoolnix extract
timestamp_v2 and I'm not yet clear about the timestamp differences I'm
observing (the muxer output maps with the timestamps, the mkvtoolnix
timestamps differ by a few ms). But I think also mkvtoolnix use a 1ms
timebase.

Also, IIRC there is no generic way to reorder PTSs, so this might
account for another difference which might be difficult to implement
generically.
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