[Ffmpeg-devel] [BUG] MPEG 2 Division By Zero

[Michael Niedermayer]

Hi

On Tue, Oct 31, 2006 at 01:52:48PM -0600, Brian Brice wrote:
> M?ns Rullg?rd wrote:
> >Brian Brice <bbrice at newtek.com> writes:
> >
> >>Brian Brice wrote:
> >>>M?ns Rullg?rd wrote:
> >>>>Brian Brice <bbrice at newtek.com> writes:
> >>>>
> >>>>>Hello.
> >>>>>
> >>>>>Something quite strange is happening when I'm encoding MPEG 2.  I'm
> >>>>>encoding clips that are just noise and I get "division by 0" crashes.
> >>>>>Unforunately, I can't produce a call stack (using DLLs in Windows from
> >>>>>VC++), but I did narrow down where the division is occurring:
> >>>>Upload a sample and tell us an FFmpeg command line that reproduces the
> >>>>error.
> >>>>
> >>>Unfortunately I'm not using the command line. :-(
> >>>I am linking to the DLLs produced by mingw/gcc from within Visual
> >>>Studio.  And I know it's not a VS problem (so don't bash, please?),
> >>>because this stuff has worked before.  I am programmatically generating
> >>>frames of noise and throwing them at the encoder.  I set only certain
> >>>members of AVCodecContext (as mentioned in the first email), and leave
> >>>the rest to default.
> >>>
> >>Sorry, I spoke too soon.  Right after I sent that message, I tried
> >>making an uncompressed AVI with this noise then using ffmpeg on the
> >>command line to reproduce.
> >>
> >>I uploaded a sample to /MPlayer/incoming/VictoriasNoise
> >>
> >>Here is a log of the execution:
> >
> >Does it crash?
> >
> 
> Yes.  Unfortunately mingw/gdb doesn't give a good backtrace.  GDB:
> (fyi, my ffmpeg binary isn't stripped)
> 
> pollux:~> gdb ./ffmpeg
> GNU gdb 6.3
> Copyright 2004 Free Software Foundation, Inc.
> GDB is free software, covered by the GNU General Public License, and you are
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> There is absolutely no warranty for GDB.  Type "show warranty" for details.
> This GDB was configured as "i686-pc-mingw32"...
> (gdb) run -i VictoriasNoise.avi -f mpeg2video -vcodec mpeg2video -b 
> 18300k -minrate 18300k -maxrate 18300k -bufsize 448K -bf 2 -an out.m2v
> FFmpeg version SVN-r6847, Copyright (c) 2000-2006 Fabrice Bellard, et al.
>   libavutil version: 49.0.2
>   libavcodec version: 51.23.0
>   libavformat version: 50.6.0
>   built on Oct 30 2006 23:12:04, gcc: 3.4.2 (mingw-special)
> Input #0, avi, from 'VictoriasNoise.avi':
>   Duration: 00:00:00.3, start: 0.000000, bitrate: 667437 kb/s
>   Stream #0.0: Video: rawvideo, bgr24, 1280x720, 29.97 fps(r)
>   Stream #0.1: Audio: pcm_s16le, 48000 Hz, stereo, 1536 kb/s
> Output #0, mpeg2video, to 'out.m2v':
>   Stream #0.0: Video: mpeg2video, yuv420p, 1280x720, q=2-31, 18300 
> kb/s, 29.97 fps(c)
> Stream mapping:
>   Stream #0.0 -> #0.0
> [mpeg2video @ 0076A000]rc buffer underflow
> [mpeg2video @ 0076A000]rc buffer underflow
> gdb: Target exception STATUS_INTEGER_DIVIDE_BY_ZERO at 0x0057b2d5
> 
> Program received signal SIGFPE, Arithmetic exception.
> 0x0057b2d5 in ff_set_mpeg4_time (s=0x0, picture_number=1) at h263.c:565
> 565             s->direct_scale_mv[0][i] = 
> (i-tab_bias)*s->pb_time/s->pp_time;
> (gdb) bt
> #0  0x0057b2d5 in ff_set_mpeg4_time (s=0x0, picture_number=1) at h263.c:565

duplicate of "[Ffmpeg-devel] [BUG] floating point exception during mpeg2video encoding"
and fixed

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

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