[FFmpeg-devel] discarding non frame data (wasskipmultiple id3v2 headers)

Michael Niedermayer michaelni
Fri Sep 24 02:10:21 CEST 2010

On Thu, Sep 23, 2010 at 03:29:54PM -0700, David Byron wrote:
> > we first need a explanation of the problem then we can
> > discuss how to solve it theres no "it causes av_read_frame
> > to return packets that only have audio"
> I want to read only the undecoded audio from an audio file in mp3, aac and
> wma files though getting the audio from any format that ffmpeg supports is a
> bonus.  I'd like to do this without having to decode the audio for
> performance reasons, not to mention not having to ship avcodec.  Is that
> enough of an explanation of the problem?

this is what you want not why it does not work

yes there are damaged files that need a flag and AVParser changes to achive
this but
as you just hacked the id3 parser to workaround a likely bug in there
somewhere this cant have affected your files.
the only thing i see is that the id3 parser likely fails and we dont know

a patch to just skip over code that contains a bug instead of searching this
bug and fixing it is not going to be accepted not in ffmpeg and not any other
half sane project
and justifying the alternative patch with a manually created by hex editor
file is also not ok

at the first step we need a _unmodified_ file that shows a problem
i will not reply any further before we have this
then someone needs to cross check this file against the id3 specs and our
parsers to see why exactly and where it fails (that someone will likely be
you or noone)
and only after this can we correct the parser for that case

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Many things microsoft did are stupid, but not doing something just because
microsoft did it is even more stupid. If everything ms did were stupid they
would be bankrupt already.
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