[Ffmpeg-devel] setting subtitle bitrate

[Borat]

Hello,

I successfully transcoded a VOB file to a new VOB file by copying its
Video-, Audio- and Subtitle-streams:

ffmpeg -i VTS_01_1.VOB -vcodec copy -acodec copy outfile.vob -scodec copy -newsubtitle

FFmpeg version SVN-r6218, Copyright (c) 2000-2004 Fabrice Bellard
  configuration:  --enable-mp3lame --enable-libogg --enable-vorbis --enable-faad --enable-faac --enable-xvid --enable-x264 --enable-mingw32 --enable-a52 --enable-dts --enable-pp --enable-gpl --enable-memalign-hack --enable-amr_nb --enable-amr_wb --enable-swscaler --enable-avisynth
  libavutil version: 49.0.0
  libavcodec version: 51.14.0
  libavformat version: 50.5.0
  built on Sep 10 2006 21:00:18, gcc: 4.0.3
Input #0, mpeg, from 'VTS_01_1.VOB':
  Duration: 00:02:19.3, start: 0.287267, bitrate: 7215 kb/s
  Stream #0.0[0x1e0]: Video: mpeg2video, yuv420p, 720x576, 8700 kb/s, 25.00 fps(r)
  Stream #0.1[0x80]: Audio: ac3, 48000 Hz, stereo, 256 kb/s
  Stream #0.2[0x20]: Subtitle: dvdsub
Output #0, vob, to 'outfile.vob':
  Stream #0.0: Video: mpeg2video, yuv420p, 720x576, q=2-31, 8700 kb/s, 25.00 fps(c)
  Stream #0.1: Audio: ac3, 48000 Hz, stereo, 256 kb/s
  Stream #0.2: Subtitle: dvdsub
Stream mapping:
  Stream #0.0 -> #0.0
  Stream #0.1 -> #0.1
  Stream #0.2 -> #0.2
frame= 3487 q=101081.0 Lsize=  121974kB time=135.2 bitrate=7390.6kbits/s
video:115950kB audio:4357kB global headers:0kB muxing overhead 1.385591%

When I do the same, but now using "dvdsub" instead of "copy" as the
subtitle codec (-scodec option), the subtitle stream seems to have
been downgraded into a stream with a low bitrate of 800 kb/s:

ffmpeg -i VTS_01_1.VOB -vcodec copy -acodec copy outfile.vob -scodec dvdsub -newsubtitle

FFmpeg version SVN-r6218, Copyright (c) 2000-2004 Fabrice Bellard
  configuration:  --enable-mp3lame --enable-libogg --enable-vorbis --enable-faad --enable-faac --enable-xvid --enable-x264 --enable-mingw32 --enable-a52 --enable-dts --enable-pp --enable-gpl --enable-memalign-hack --enable-amr_nb --enable-amr_wb --enable-swscaler --enable-avisynth
  libavutil version: 49.0.0
  libavcodec version: 51.14.0
  libavformat version: 50.5.0
  built on Sep 10 2006 21:00:18, gcc: 4.0.3
Input #0, mpeg, from 'VTS_01_1.VOB':
  Duration: 00:02:19.3, start: 0.287267, bitrate: 7215 kb/s
  Stream #0.0[0x1e0]: Video: mpeg2video, yuv420p, 720x576, 8700 kb/s, 25.00 fps(r)
  Stream #0.1[0x80]: Audio: ac3, 48000 Hz, stereo, 256 kb/s
  Stream #0.2[0x20]: Subtitle: dvdsub
Output #0, vob, to 'outfile.vob':
  Stream #0.0: Video: mpeg2video, yuv420p, 720x576, q=2-31, 8700 kb/s, 25.00 fps(c)
  Stream #0.1: Audio: ac3, 48000 Hz, stereo, 256 kb/s
  Stream #0.2: Subtitle: dvdsub, 800 kb/s
Stream mapping:
  Stream #0.0 -> #0.0
  Stream #0.1 -> #0.1
  Stream #0.2 -> #0.2
frame= 3487 q=19424.6 Lsize=  121934kB time=135.2 bitrate=7388.2kbits/s
video:115950kB audio:4357kB global headers:0kB muxing overhead 1.352342%

Is there a way to specify the subtitle stream's bitrate (change it
from the default of 800 kb/s), just like the -b option for video and
the -ab option for audio (something like a -sb option for subtitle)?
Or any way to change some properties of the subtitle output?

Thanks!