[MPlayer-dev-eng] [PATCH] Dolby TrueHD support for mkv demuxer

[Aurelien Jacobs]

On Thu, Aug 06, 2009 at 10:10:32PM +0200, Grigori Goronzy wrote:
> Aurelien Jacobs wrote:
> > nobody ???
> > Anyway, in case you didn't realize, ffmpeg settled on a bitstream to
> > export ASS track (this is not especially related to the mkv demuxer).
> > This bitstream format won't change unless you propose a patch on ffmpeg-devel.
> 
> Is there actually a container besides Matroska that embeds ASS/SSA and
> is in active use?  To my knowledge not, and it won't change in the near
> future either. So, why is the new bitstream format needed?

First of all, .ass files themselves !
Then AFAIR, the nut container, and maybe also AVI.
lavf uses CODEC_ID_ASS for straight .ass file demuxer, and MPlayer should
support that, independently of the way it handles mkv...

> Besides, there are several problems with your patch and the format.
> - The patch breaks the internal mkv demuxer.

see commit r27529 for the fix.

> - The ffmpeg format does not have the ReadOrder field, so you can't
> check for duplicate events easily and your patch currently doesn't do
> that at all.

Obviously you can't check for duplicate events ! And that's a good thing.
Because it is absolutely useless to check for duplicate.
I think that the check for duplicate was added in libass because of a
deficiency of the native mkv demuxer.
Workarounding bugs of demuxers inside libass is damn ugly.

> - SSA/ASS timestamps have centisecond accuracy, while Matroska
> timestamps usually have millisecond accuracy.  This might cause problems...

If it actually causes any real life problem, please fill a bug repport about
this !

> There IS breakage with this patch. A lot of it.

Can you please point at any actual, real life breakage (that is not fixed
by r27529) ?

> >  3) support both format inside MPlayer (quite ugly and redundant, and will
> >     become useless when native mkv demuxer will be removed from MPlayer)
> 
> I've heard more than one person voice that the lavf demuxer has its
> share of problems

Why the hell those people don't fill issues on ffmpeg tracker ???

> and isn't easy to understand or to work with.

It is much easier to work with than mplayer native demuxer.

>  And from a user's POV, if I remember correctly, I had some problems with it
> as well.

Please, please, please, fill bug repports about those !!!
I think that's the very reason why lavf mkv demuxer should be the default
one in MPlayer. Because without this, people just don't care about sending
bug repports...

Aurel