[Ffmpeg-user] problem encoding DVD to MP4

[Mario Rossi]

I'm having a lot of troubles encoding a DVD in the iPod format mp4.

This is the output of ffmpeg (latest svn build)

ffmpeg -i mobile.avi -f mp4 -vcodec mpeg4 -qscale 4 -acodec aac -ab 96
-mbd 2 -s 640x360 output.ffmpeg.mp4

FFmpeg version SVN-r7659, Copyright (c) 2000-2006 Fabrice Bellard, et al.
  configuration:  --enable-mp3lame --enable-libogg --enable-vorbis
--enable-xvid --enable-x264 --enable-gpl --enable-pp --enable-shared
--disable-ipv6 --enable-pthreads --enable-faac --enable-faad
--enable-a52 --enable-dts
  libavutil version: 49.2.0
  libavcodec version: 51.29.0
  libavformat version: 51.8.0
  built on Jan 23 2007 10:48:24, gcc: 4.1.1 20060525 (Red Hat 4.1.1-1)
Input #0, avi, from 'mobile.avi':
  Duration: 00:35:28.2, start: 0.000000, bitrate: 4923 kb/s
  Stream #0.0: Video: mpeg2video, yuv420p, 720x576, 7500 kb/s, 25.00 fps(r)
  Stream #0.1: Audio: ac3, 48000 Hz, stereo, 192 kb/s
Output #0, mp4, to 'V_1_A_1.ffmpeg.mp4':
  Stream #0.0: Video: mpeg4 (hq), yuv420p, 640x360, q=2-31, 200 kb/s,
25.00 fps(c)
  Stream #0.1: Audio: aac, 48000 Hz, stereo, 96 kb/s
Stream mapping:
  Stream #0.0 -> #0.0
  Stream #0.1 -> #0.1
Press [q] to stop encoding
[ac3 @ 0xb7dd3e64]Error decoding frame
[ac3 @ 0xb7dd3e64]Error decoding frame=1758.8 bitrate=1090.0kbits/s
[ac3 @ 0xb7dd3e64]Error decoding frame=2128.0 bitrate=1117.8kbits/s
frame=62454 q=4.0 Lsize=  348413kB time=2497.2 bitrate=1142.9kbits/s
video:317717kB audio:29265kB global headers:0kB muxing overhead 0.412354%

It seems that my DVD has got a bad ac3 frame at time 1758.8 : I think
there is not much I can do about that.
But the problem is that at the end (2128 sec = 00:35:28) there is an
other bad ac3 frame (maybe is just the way mencoder generates the
input) and it jumps back to the first error reencoding everything from
1758 till the end.

So the final length is 2497 sec = 00:41:37 instead of 00:35:28 as
reported initially.
And the surplus is exactly the time after the bad ac3 at 1758 till the end.

The input file has been generated with mencoder

mencoder -ovc copy -oac copy -alang en dvd:// -chapter 1-11 -o mobile.avi

Is there anything I can do other that forcing an end time with "-t".
Maybe there is an option to deal in a better way with input problems.

Cheers