simon@SimonSimCity-Mac:Movies$ ffmpeg -f concat -i clip1.txt clip1.vob
ffmpeg version 1.2.1 Copyright (c) 2000-2013 the FFmpeg developers
  built on Jul 16 2013 14:50:39 with Apple LLVM version 4.2 (clang-425.0.28) (based on LLVM 3.2svn)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/1.2.1 --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-nonfree --enable-hardcoded-tables --enable-avresample --enable-vda --cc=cc --host-cflags= --host-ldflags= --enable-libx264 --enable-libfaac --enable-libmp3lame --enable-libxvid
  libavutil      52. 18.100 / 52. 18.100
  libavcodec     54. 92.100 / 54. 92.100
  libavformat    54. 63.104 / 54. 63.104
  libavdevice    54.  3.103 / 54.  3.103
  libavfilter     3. 42.103 /  3. 42.103
  libswscale      2.  2.100 /  2.  2.100
  libswresample   0. 17.102 /  0. 17.102
  libpostproc    52.  2.100 / 52.  2.100
[mpeg @ 0x7fe7b981ca00] max_analyze_duration 5000000 reached at 5024000 microseconds
[concat @ 0x7fe7b981c400] max_analyze_duration 5000000 reached at 5000000 microseconds
[concat @ 0x7fe7b981c400] Estimating duration from bitrate, this may be inaccurate
Input #0, concat, from 'clip1.txt':
  Duration: 00:00:00.00, start: 0.000000, bitrate: 224 kb/s
    Stream #0:0: Video: mpeg2video (Main), yuv420p, 720x576 [SAR 16:15 DAR 4:3], 25 fps, 25 tbr, 90k tbn, 50 tbc
    Stream #0:1: Audio: ac3, 48000 Hz, stereo, fltp, 224 kb/s
File 'clip1.vob' already exists. Overwrite ? [y/N] y
VBV buffer size not set, muxing may fail
Output #0, svcd, to 'clip1.vob':
  Metadata:
    encoder         : Lavf54.63.104
    Stream #0:0: Video: mpeg2video, yuv420p, 720x576 [SAR 16:15 DAR 4:3], q=2-31, 200 kb/s, 90k tbn, 25 tbc
    Stream #0:1: Audio: mp2, 48000 Hz, stereo, s16, 128 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (mpeg2video -> mpeg2video)
  Stream #0:1 -> #0:1 (ac3 -> mp2)
Press [q] to stop, [?] for help
[ac3 @ 0x7fe7b9850400] frame sync error
Error while decoding stream #0:1: Operation not permitted
[svcd @ 0x7fe7b9852400] st:0 PTS: 7740 DTS: 7740 < 8459 invalid, clipping
max_analyze_duration 5000000 reached at 5000000 microsecondsbitrate= 534.0kbits/s dup=5 drop=0
[ac3 @ 0x7fe7b9850400] frame sync error
Error while decoding stream #0:1: Operation not permitted
[svcd @ 0x7fe7b9852400] st:0 PTS: 1649340 DTS: 1649340 < 1650059 invalid, clipping
DTS discontinuity in stream 1: packet 3 with DTS 50761, packet 4 with DTS 53641/s dup=7 drop=0
[mpeg @ 0x7fe7b9851600] max_analyze_duration 5000000 reached at 5000000 microseconds
[ac3 @ 0x7fe7b9850400] frame sync error
Error while decoding stream #0:1: Operation not permitted
[svcd @ 0x7fe7b9852400] st:0 PTS: 3556620 DTS: 3556620 < 3557339 invalid, clipping
DTS discontinuity in stream 1: packet 3 with DTS 50761, packet 4 with DTS 53641/s dup=11 drop=0
[mpeg @ 0x7fe7ba067c00] max_analyze_duration 5000000 reached at 5000000 microseconds
[ac3 @ 0x7fe7b9850400] frame sync error
Error while decoding stream #0:1: Operation not permitted
[svcd @ 0x7fe7b9852400] st:0 PTS: 7033500 DTS: 7033500 < 7034219 invalid, clipping
frame= 2295 fps=721 q=31.0 Lsize=    5554kB time=00:01:31.80 bitrate= 495.6kbits/s dup=12 drop=0
video:4039kB audio:1434kB subtitle:0 global headers:0kB muxing overhead 1.481840%