[FFmpeg-devel] skip multiple id3v2 headers

Michael Niedermayer michaelni
Wed Sep 15 02:43:43 CEST 2010

On Tue, Sep 14, 2010 at 04:39:54PM -0700, David Byron wrote:
> > > We know where the id3v2 tag ends.
> > 
> > no you dont
> >
> > you know parsing the id3v2 tag failed you dont know why it
> > failed.
> Ignoring for the moment how that field became invalid, isn't it clear that
> parsing failed because the length of one frame is invalid?
> > you only "know" it because you changed one field and not the
> > other by hand.
> What other field?

That one that tells you how large the id3v2 thing is

> > > Maybe the bug is only in the documentation,
> > 
> > yes, ive fixed that
> Thanks.  Now it's clear that av_read_packet is a lot less helpful than I
> think it could be.  Do you have a suggestion for how to get at the undecoded
> audio in a file?

if there is a valid use case iam sure that can be implemented.
I see many options, a flag that tells parsers to discard non frame data might
be a possibility ...

> Is there a way to find out what subset of each packet is audio?
> avcodec_decode_audio3 doesn't seem to help in this case as it returns -1 on

a patch for the mpeg audio decode frame code is welcome so it searches for a
valid frame header

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

The misfortune of the wise is better than the prosperity of the fool.
-- Epicurus
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