[FFmpeg-devel] [PATCH] [PATCH]: Fix AVI demuxing when the input is in streaming mode.

[Michael Niedermayer]

On Wed, Mar 27, 2013 at 08:48:41PM -0700, Thierry Foucu wrote:
> On Wed, Mar 27, 2013 at 6:53 PM, Michael Niedermayer <michaelni at gmx.at>wrote:
> 
> > On Wed, Mar 27, 2013 at 05:47:03PM -0700, Thierry Foucu wrote:
> > > ---
> > >  libavformat/avidec.c | 10 +++++++---
> > >  1 file changed, 7 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/libavformat/avidec.c b/libavformat/avidec.c
> > > index f6eb71e..121033f 100644
> > > --- a/libavformat/avidec.c
> > > +++ b/libavformat/avidec.c
> > > @@ -374,9 +374,13 @@ static int avi_read_header(AVFormatContext *s)
> > >
> > >      av_log(avi, AV_LOG_DEBUG, "use odml:%d\n", avi->use_odml);
> > >
> > > -    avi->io_fsize = avi->fsize = avio_size(pb);
> > > -    if(avi->fsize<=0 || avi->fsize < avi->riff_end)
> > > -        avi->fsize= avi->riff_end == 8 ? INT64_MAX : avi->riff_end;
> > > +    if (pb->seekable) {
> > > +        avi->io_fsize = avi->fsize = avio_size(pb);
> > > +        if(avi->fsize<=0 || avi->fsize < avi->riff_end)
> > > +            avi->fsize= avi->riff_end == 8 ? INT64_MAX : avi->riff_end;
> > > +    } else {
> > > +        avi->fsize = avi->riff_end = INT64_MAX;
> > > +    }
> >
> > This looks a bit odd, i thought this code already handled non seekable
> > cases correctly.
> > The only issue i can see is that fsize is possibly missing an
> > update in case of multiple riff chunks or frames going beyond the
> > riff_end.
> > setting fsize & riff_end to INT64_MAX would remove one way of limiting
> > packet sizes and malloc sizes possibly resulting in huge memory
> > allocations and reading to EOF on damaged files.
> >
> > How can i reproduce the issue this fixes ?
> >
> 
> 
> You need to have a AVI file grater than 1GB byte and using a pipe as input
> to ffmpeg.
> 
> here are the step we used to reproduce the problem:
> 
> 1- create a large AVI file. This should create a file of 7s video of 1.7GB
> size
> 
>  ffmpeg -lavfi -i mandelbrot=s=1920x1080:r=30 -t 7 -y -vcodec rawvideo
> /tmp/video.avi
> 
> 2- create a fifo and cat the file to it
> 
> mkfifo video; cat /tmp/video.avi > video &
> 
> 3- using ffprobe on the fifo
> 
> ffprobe -show_packets -print_format compact -i video
> 
> The last video frame showing by ffprobe will be
> packet|codec_type=video|stream_index=0|pts=129|pts_time=4.300000|dts=129|dts_time=4.300000|duration=1|duration_time=0.033333|convergence_duration=N/A|convergence_duration_time=N/A|size=8294400|pos=1069984390|flags=K
> 
> note the pts is 4.3 second and ffprobe continue to parse the file, but does
> not output any more information.

should be fixed

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

Everything should be made as simple as possible, but not simpler.
-- Albert Einstein
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