[Ffmpeg-devel] [PATCH] MP3 decoding from RTP stream. Getting "invalid new backstep"

[Guillaume POIRIER]

Hi,

On 11/6/06, Michael Niedermayer <michaelni at gmx.at> wrote:
> On Mon, Nov 06, 2006 at 06:10:28PM +0100, Guillaume POIRIER wrote:
> > On 11/6/06, Michael Niedermayer <michaelni at gmx.at> wrote:
> > >On Mon, Nov 06, 2006 at 05:44:07PM +0100, Martin wrote:
> > >> Michael Niedermayer wrote:
> >
> > [..]
> >
> > >> > the whole above should be replaced by a if (discard_frame) \n
> > >memset(..., 0, ...)
> > >> > as already said
> > >> >
> > >> > [...]
> > >>
> > >> Ok, I didn't see that. Obviously its much better that way... :)
> > >> Attached the updated patch. Hope everything is finally ok now... ;)
> > >
> > >looks ok
> > >
> > >whoever applies this should test it with a damaged mp3 though
> >
> > I don't have one on hand. Martin, please provide the damaged mp3 that
> > your patch is supposed to improve support for.
>
> try the attached program (but make a backup first ;) )

Ok, I finaly found some time to test this patch with the trasher. I'm
really sorry for the delay.

I'm sorry to say that your patch doesn't seem to work for me, at least
with an mp3 sample trashed by Michael's trasher. Actually, I think
that Michael's trasher doesn't trash files in a way that make lavc
display the message "invalid new backstep".
All I'm getting is this:
DISPLAY=:0 ./ffplay_g /tmp/01-ya_pas_darrangement.mp3
bits_left=-6
overread, skip -10 enddists: -4 -4
mdb:127, lastbuf:95 skiping granule 0
bits_left=-1
bits_left=-3
mdb:145, lastbuf:49 skiping granule 0
bits_left=-5
overread, skip -5 enddists: -3 -3
overread, skip -7 enddists: -2 -2
overread, skip -7 enddists: -1 -1
mdb:129, lastbuf:25 skiping granule 0
bits_left=-2
overread, skip -7 enddists: -1 -1
overread, skip -8 enddists: -6 -6
mdb:105, lastbuf:19 skiping granule 0
bits_left=-7
overread, skip -8 enddists: -4 -4
overread, skip -6 enddists: -3 -3
overread, skip -6 enddists: -4 -4
overread, skip -7 enddists: -6 -6
mdb:19, lastbuf:16 skiping granule 0
overread, skip -9 enddists: -8 -8
overread, skip -5 enddists: -3 -3
mdb:75, lastbuf:25 skiping granule 0
overread, skip -6 enddists: -2 -2
overread, skip -7 enddists: -2 -2
overread, skip -5 enddists: -2 -2
overread, skip -7 enddists: -2 -2
overread, skip -7 enddists: -2 -2

[..]

I can clearly hear corruptions that indicate that the mp3 file was
corrupted, but that's about it! :-(

Sorry, but it looks like I'd need a sample that exhibits the very
problem that your patch is supposed to fix :-(

Guillaume
-- 
An association of men who will not quarrel with one another is a thing
which has never yet existed, from the greatest confederacy of nations
down to a town meeting or a vestry.
 -- Thomas Jefferson
(when interviewed about MPlayer ML flamewars)
http://www.brainyquote.com/quotes/quotes/t/thomasjeff157207.html