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

Michael Niedermayer michaelni
Wed Aug 26 18:36:01 CEST 2009


On Wed, Aug 26, 2009 at 01:34:45PM +0200, Reimar D?ffinger wrote:
> On Wed, Aug 26, 2009 at 10:47:14AM +0000, Carl Eugen Hoyos wrote:
> > Reimar D?ffinger <Reimar.Doeffinger <at> gmx.de> writes:
> > 
> > > 
> > > On Wed, Aug 26, 2009 at 11:00:52AM +0200, Reimar D?ffinger wrote:
> > > > When muxing into AVI for xsub I first get a crash, and after fixing that
> > > > I get "scale/rate is 0/1 which is invalid. (This file has been generated by
> > > > broken software.)" when trying to play the result.
> > > 
> > > Ok, I have a couple of issue with the AVI demuxer and other stuff.
> > > The first one is that the time base of subtitle streams stays at
> > > the default of 90 kHz, which is a bit questionable but probably
> > > acceptable.
> > > The second and bigger one is that the avi muxer uses the (completely
> > > undocumented btw.) ff_parse_specific_params which seems to guess a time
> > > base.
> > > The issue with this is that for this it uses the codec values and only
> > > those, which are never set for subtitles, overwriting the perfectly
> > > good values from the stream time base. WTF?
> > > Later this causes a crash due to a division by 0 when rescaling the
> > > subtitle time base to the now broken stream time base.
> > > This "fixes" it, but I have no idea if it makes anything actually work:
> > 
> > With the patch, subtitles are actually encoded (file size 10 times bigger), but
> > nothing is shown on playback: Perhaps because of these messages while encoding:
> > [xsub @ 0x141e450]No more than 4 subtitle colors supported (256 found.)
> >     Last message repeated 6 times
> 
> No, you need this patch, but Michael will have to comment on what is the
> right approach (it disables empty packets for timestamp encoding for
> subtitles, which causes the massive size increase):

"the right approuch" is what is written in the spec in question about
the specific subtitle format

if subtitles are placed in more than a single packet a timebase and likely
dummy 0 packets are needed in avi. But as said the question is how should
the correct avi file look like ...


[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Asymptotically faster algorithms should always be preferred if you have
asymptotical amounts of data
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