[FFmpeg-devel] [PATCH] Bluray Subtitle Support, v7 (Updated patch to v12)

Michael Niedermayer michaelni
Thu Aug 27 03:44:19 CEST 2009

On Wed, Aug 26, 2009 at 09:31:05PM +0200, Reimar D?ffinger wrote:
> On Wed, Aug 26, 2009 at 09:03:15PM +0200, Michael Niedermayer wrote:
> > On Wed, Aug 26, 2009 at 08:48:02PM +0200, Reimar D?ffinger wrote:
> > > > the internal timebase should be set to whichever value the timebase of
> > > > the subs has (ms ?)
> > > 
> > > Yes, that can be done in the stream creation logic, but first the AVI
> > > demuxer must be stopped from overwriting it with bogus codec values.
> > 
> > but does it at all?
> > isnt it rather feeded with a bogus timebase?
> I think that's not documented. 

yes, sadly

> Are demuxers supposed to use
> st->codec->time_base and overwrite st->time_base?
> Why should they even look in st->codec when there is the "same" thing
> one level lower?
> Without further explanation it seems quite idiotic to me, especially
> when a perfectly fine value gets override by obvious nonsense.

If iam not mistaken st->time_base is a pure output variable and the user
cannot set it to begin with, also ive just checked and mplayer also does
not set it when muxing to lavf, rather it sets the AVCodecContext part.

st->time_base is set from the muxer and might be the stream timebase
1/90000 1/1000000 or something entirely different.

If you have suggestions on improvig the api and or patches to document
it, its all welcome ....

> > > That is rather independent though IMO, since we have that issue already
> > > with the original .divx files.
> > 
> > > Also that will break transcoding, resulting in the message "Subtitle
> > > packets must have a pts", despite the fact that all the necessary info
> > > is there after decoding.
> > 
> > by the time ffmpeg.c sees the packet the parser alraedy did run and fill
> > a pts in
> As long as there is no parser it won't... As soon as someone writes a
> parser, fine, but I am not ok with breaking the only way to test xsub
> transcoding and just hoping for someone to fix it again.

iam not completely sure what you object to, but if i guess correctly that
would be ommiting wrong timestamps from xsub packets? well we can leave them
for now until a parser has been written still its kinda hackish way to test

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Opposition brings concord. Out of discord comes the fairest harmony.
-- Heraclitus
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