[FFmpeg-devel] id3v2 TSSE tag

[Michael Niedermayer]

On Sat, Oct 17, 2009 at 09:37:48PM -0400, Justin Ruggles wrote:
> Michael Niedermayer wrote:
> 
> > On Sat, Oct 17, 2009 at 06:46:20PM -0400, Justin Ruggles wrote:
> >> Hi,
> >>
> >> Currently, if the TSSE tag exists, the mp3 muxer writes it twice.  It
> >> writes the original value as a TXXX/TSSE tag, then it writes a new TSSE
> >> tag with the lavf version.  Is this the intended behavior?
> > 
> > i doubt thats intended ....
> > hmm
> > * the demuxer should return all tags
> > * TSSE ?? what is TSSE? shouldnt that be renamed to something sane?
> >   we likely dont want "TSSE" to be stored in mov when transcoding
> 
> According to the specs, TSSE is "Software/Hardware and settings used for
> encoding".  iTunes mp4 uses "?too", mov uses "?enc", and nut uses
> "Encoder".  I think using "encoder" as the generic value would be a good
> choice.

there is a encoder for each stream and there is a muxer. Iam not sure
but these concepts seem mixed ...


> 
> > The question imho is should the muxer drop the encoder/muxer version
> > if it finds one in the metadata or should ffmpeg.c filter it out ...
> > iam not sure about which is better ATM
> 
> With our current metadata system, it seems more appropriate to do it at
> the user level.  ffmpeg.c knows if stream copy is being used.  It could
> leave the existing value alone if stream copy is being used and filter
> it out otherwise.
> 

> I know we already write LIBAVFORMAT_IDENT as a new tag in several
> muxers, but I'm not sure it's a good idea for them to be creating new
> tags that are not in AVMetadata.  The encoder version and/or settings
> can be added to AVMetadata at the user level if desired.

LIBAVFORMAT_IDENT has primarely 1 purpose and that is for the demuxer to
detect lavf generated files to work around possible bugs. I think we
dont have to do that anywhere, but at the codec side divx, xvid, lavc,
x264 all had been hit by bugs that required their idents for workarounds
in the decoder.
If our muxer ever ommits this IDENT or copies some other muxers ident then
this detecting lavf generated files reliably could become tricky

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

When the tyrant has disposed of foreign enemies by conquest or treaty, and
there is nothing more to fear from them, then he is always stirring up
some war or other, in order that the people may require a leader. -- Plato
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 189 bytes
Desc: Digital signature
URL: <http://lists.mplayerhq.hu/pipermail/ffmpeg-devel/attachments/20091018/d06b3684/attachment.pgp>