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

David Byron dbyron
Fri Sep 24 00:29:54 CEST 2010

> 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?

For mp3 files specifically, I define audio as anything that's a valid mpeg
frame.  If I don't get VBR headers that's OK, but it's also OK for me to get
them.  But, if a file has id3v2 tags at the beginning, or lyrics3, ape or
id3v1 tags at the end then I want to ignore them.  It also means that if
there are non-audio bytes between mpeg frames that av_read_frame doesn't
return them.

I haven't spent as much time with the other formats so I'm not sure what
complications will arise there.

av_read_frame seemed like a good way to get this info but I'd love to hear
about other ways to go about it.

Thanks much.


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