[MPlayer-dev-eng] Re: [Patch] Audio detection

Alban Bedel albeu at free.fr
Wed Mar 24 23:51:19 CET 2004

Hi Arpi,

on Wed, 24 Mar 2004 18:31:59 +0100 (CET) you wrote:

> Hi,
> > Hello,
> > I forgot to mention that my patch might also solve nehals problem,
> > at least it does not skip the first frame if it is followed by valid 
> > ones. So please apply ;-)
> > 
> > Michael
> many mp3 files has bad first frame.
> the most common cases are ascii art/nfo file in fake 2048 bytes frame
> at the beginning of the file, and the xing vbr header.
> they must be skipped before the decoder gets the samplerate/channels etc
> info from them.

For those still not conviced and/or willing to improve mp3lib i uploaded
a samples broken-first-frame.mp3 wich is inited at 32KHz instead of 44KHz.
BTW it seems to also fail with the patch submited, even when mp3lib
skip its frame. 

> anyway i see there is a big problem: where should it be skipped?
> in the demuxer? easy to do in demux_audio, but what about mp3 tracks
> of avi, ogm etc?
> in the codec? then at least mp3lib, libmad and libavcodec should be
> able to do it. currently (afaik) only mp3lib skips the first frame.

In the codec seems better to me, so stream copy is as close as
possible to the original. Those who want to mux proper mp3 stream
would appreciate.


Everything is controlled by a small evil group
to which, unfortunately, no one we know belongs.

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