[Ffmpeg-devel] -ss having trouble with VOB file: bug?

Rodrigo Severo rodrigo
Wed Apr 19 21:10:05 CEST 2006

Dear list,

I want to decode a VOB file into raw video/audio. I want ffmpeg to skip the
begining of the clip. When I add the -ss option before -i, ffmpeg won't
decode anything with some strange message, i.e., messages I can't

Here is the result of my last try from inside gdb:

bin # gdb ./ffmpeg
GNU gdb 6.4
Copyright 2005 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "i686-pc-linux-gnu"...Using host libthread_db
library "/lib/libthread_db.so.1".

(gdb) r -y -v 512 -ss 00:00:31 -i /mnt/temp/VIDEO_TS/VTS_01_1.VOB -f avi
-vcodec rawvideo -acodec pcm_s16le /rip/teste/bug-ffmpeg_cvs-seek.avi
Starting program: /usr/local/ffmpeg-200604191222/bin/ffmpeg -y -v 512 -ss
00:00:31 -i /mnt/temp/VIDEO_TS/VTS_01_1.VOB -f avi -vcodec rawvideo -acodec
pcm_s16le /rip/teste/bug-ffmpeg_cvs-seek.avi
FFmpeg version CVS, Copyright (c) 2000-2004 Fabrice Bellard
  configuration:  --prefix=/usr/local/ffmpeg-200604191222 --disable-static
--enable-shared --cc=i686-pc-linux-gnu-gcc --extra-ldflags= --disable-mmx
--disable-altivec --disable-v4l --disable-v4l2 --disable-dv1394
--disable-network --disable-opts --enable-mp3lame --enable-a52 --enable-xvid
--enable-libogg --enable-vorbis --enable-theora --enable-dts --enable-x264
--enable-faad --enable-faac --enable-gpl --enable-pp --disable-strip
  libavutil version: 49.0.0
  libavcodec version: 51.9.0
  libavformat version: 50.4.0
  built on Apr 19 2006 16:06:50, gcc: 3.4.5 (Gentoo 3.4.5-r1, ssp-3.4.5-1.0,
[mpeg @ 0xb7f2d600]read_seek: 0 2810283
[mpeg @ 0xb7f2d600]using cached pos_min=0x3ff4380e dts_min=1216088
[mpeg @ 0xb7f2d600]pos_min=0x3ff4380e pos_max=0x3ff6c80e dts_min=1216088
[mpeg @ 0xb7f2d600]1072969742 1073137678 1073137678 / 1216088 1231103
1231103 target:2810283 limit:1073137678 start:1073137678 noc:1
[mpeg @ 0xb7f2d600]pos=0x3ff6c80e 1231103<=2810283<=-9223372036854775808
Input #0, mpeg, from '/mnt/temp/VIDEO_TS/VTS_01_1.VOB':
  Duration: 00:00:13.2, start: 0.225367, bitrate: 646161 kb/s
  Stream #0.0[0x1e0], 1/90000, 29.97 fps(r): Video: mpeg2video, yuv420p,
704x480, 1001/30000, 9558 kb/s
  Stream #0.1[0x80], 1/90000: Audio: ac3, 48000 Hz, stereo, 256 kb/s
Output #0, avi, to '/rip/teste/bug-ffmpeg_cvs-seek.avi':
  Stream #0.0, 1/90000, 29.97 fps(c): Video: rawvideo, yuv420p, 704x480,
1001/30000, q=2-31, 200 kb/s
  Stream #0.1, 1/90000: Audio: pcm_s16le, 48000 Hz, stereo, 1536 kb/s
Stream mapping:
  Stream #0.0 -> #0.0
  Stream #0.1 -> #0.1
Press [q] to stop encoding
[mpeg2video @ 0xb7e53004]ac-tex damaged at 40 10
[mpeg2video @ 0xb7e53004]Warning MVs not available
[mpeg2video @ 0xb7e53004]concealing 880 DC, 880 AC, 880 MV errors
*** drop!
frame=    0 q=0.0 Lsize=       9kB time=10000000000.0 bitrate=   0.0kbits/s
dup=0 drop=1
video:0kB audio:0kB global headers:0kB muxing overhead inf%

Program exited normally.

As you can see this last try was made with a fresh-from-cvs version.

If I try the same thing on the same VOB file with transcode I succeed.
Partly at least, I get a problem with the audio being distorted but I
believe this is entirely other issue. I mention transcode here just to say
that the VOB file is seekable.

Is this a bug in ffmpeg?

Rodrigo Severo

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