[FFmpeg-devel] BUG in use of extradata and extradata_size with dvb subtitles and teletext

[Michael Niedermayer]

On Wed, Jan 08, 2014 at 05:33:59PM +0100, Michael Niedermayer wrote:
> On Wed, Jan 08, 2014 at 06:15:19PM +0200, Andriy Lysnevych wrote:
> > Any way we must fix this bug at some point. Having two DVB subtitle formats
> > in FFmpeg already caused a lot of related issues.
> > 
> > Applying only libavcodec change will break DVB subtitle encoder -> MPEG-TS
> > muxer chain and as the result output MPEG-TS stream will contain malformed
> > DVB subtitle payload.
> > 
> > To keep compatibility we can check version of libavformat in DVB subtitle
> > encoder and add beginning 0x00 and trailing 0xFF bytes for older versions
> > as it was before. To do so we must increase version of libavformat with
> > this patch.
> > 
> > Questions are:
> 
> > 1) How to detect libavformat version from libavcodec? Is calling
> > avformat_version() ok?
> 
> no
> libavcodec has no way to detect the libavformat its used with or even
> if its used with any libavformat or different code.
> 
> I think there are only 2 (reasonable) solutions
> A. what ubitux suggested, that a option is added and the default stays
>    the old format and the application would have to set it to have
>    the new format used
> B. just accept that the format was buggy&broken and that this is a bug
>    fix
> 
> Did any application use / depend on this specific "buggy" format ?
> 

> I think ubitux and any application developers affected by this are
> the best to decide of B. is acceptable

and if noone replies then you can probably assume its ok and noone
knows of any code that depends on this format 

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

You can kill me, but you cannot change the truth.
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