[FFmpeg-devel] [Ffmpeg-user] chroma errors on movie file.

[Michael Niedermayer]

Hi

On Thu, Aug 30, 2007 at 02:40:44PM +0200, Baptiste Coudurier wrote:
> Baptiste Coudurier wrote:
> > Hi Aurelien,
> > 
> > Aurelien Jacobs wrote:
> >> On Fri, 10 Aug 2007 07:43:27 +0200
> >> Benjamin Larsson <banan at ludd.ltu.se> wrote:
> >>
> >>> gga wrote:
> >>>> gga wrote:
> >>>>> Using latest svn ffmpeg, this file:
> >>>>> http://www.encuadre.com.ar/videos/manfredi/OLOCOONS_O3.mov
> >>>>>
> >>>>> results in ffmpeg decoding the video incorrectly, with errors about
> >>>>> chroma, among others.  This is using an svq3 codec.
> >>>>> Can anyone confirm?
> >>>>>
> >>>> Oh yes, I should mention this is with ffplay itself.  mplayer or vlc
> >>>> will read the file fine with their demuxers/decoders.
> >>>>
> >>>>
> >>> Works for me without any visible errors with an old ffplay version. Get
> >>> lots of errors with a fairly new one. So the report seems to be valid.
> >> Confirmed. The bug seems to be demuxer related. It works fine with
> >> mplayer's native demuxer but don't work with mplayer -demuxer lavf.
> >> Baptiste ?
> > 
> > It seems, yes. I'll be in vacation tonight for 2 weeks, so I won't have
> > any computer to look at it :/
> > 
> 
> Ok, problem is that "fiel" atom parsing overwrites extradata in
> mov_read_extradata (overwrite 'SMI ' atom), so decoder fails to decode
> stream. Attached patch makes mov_read_extradata appending atoms in
> extradata. svq3 decoder will search for 'SEQH' sequence (contained in
> 'SMI ') in extradata.
> 
> Michael is it ok for you ?

yes, except:

[...]

> Index: libavformat/mov.c
> ===================================================================
> --- libavformat/mov.c	(revision 10249)
> +++ libavformat/mov.c	(working copy)
> @@ -470,14 +470,25 @@
>  static int mov_read_extradata(MOVContext *c, ByteIOContext *pb, MOV_atom_t atom)
>  {
>      AVStream *st = c->fc->streams[c->fc->nb_streams-1];
> +    uint8_t *data_ptr;
> +    if (st->codec->extradata) {
> +        unsigned old_size = st->codec->extradata_size;
> +        if((uint64_t)atom.size > (1<<30) - old_size - 8)
> +            return -1;

this check
if old_size for example is 1<<30 this check fails

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

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