[FFmpeg-user] channelsplit seems to mute one channel

[Owen Jones]

I am trying to use the channelsplit filter to split a single stereo channel into two separate channels. However when I look at the resulting file in Quicktime (sorry don't know a better way to check this with ffprobe) the second (right) channel appears as disabled. Am I doing something wrong, or is there a way to force a channel to be enabled?

ffmpeg -i VTS_01_1.VOB -codec:v copy -codec:a pcm_s16le -map 0 -filter_complex 'channelsplit' test.mov
ffmpeg version 1.1.git-0d194ee Copyright (c) 2000-2013 the FFmpeg developers
  built on Feb  8 2013 09:49:39 with Apple clang version 4.1 (tags/Apple/clang-421.11.66) (based on LLVM 3.1svn)
  configuration: --enable-nonfree --enable-gpl --enable-version3 --enable-postproc --enable-swscale --enable-avfilter --enable-libmp3lame --enable-libvorbis --enable-libtheora --enable-libfaac --enable-libxvid --enable-libx264 --enable-libvpx --enable-hardcoded-tables --enable-shared --enable-pthreads --disable-indevs --cc=clang
  libavutil      52. 17.101 / 52. 17.101
  libavcodec     54. 91.102 / 54. 91.102
  libavformat    54. 61.104 / 54. 61.104
  libavdevice    54.  3.103 / 54.  3.103
  libavfilter     3. 35.101 /  3. 35.101
  libswscale      2.  2.100 /  2.  2.100
  libswresample   0. 17.102 /  0. 17.102
  libpostproc    52.  2.100 / 52.  2.100
[mpeg @ 0x7fcc88806600] max_analyze_duration 5000000 reached at 5000000 microseconds
Input #0, mpeg, from 'VTS_01_1.VOB':
  Duration: 00:00:10.60, start: 0.235211, bitrate: 803800 kb/s
    Stream #0:0[0x1e0]: Video: mpeg2video (Main), yuv420p, 720x576 [SAR 16:15 DAR 4:3], 25 fps, 25 tbr, 90k tbn, 50 tbc
    Stream #0:1[0x80]: Audio: ac3, 48000 Hz, stereo, fltp, 256 kb/s
Output #0, mov, to 'test.mov':
  Metadata:
    encoder         : Lavf54.61.104
    Stream #0:0: Audio: pcm_s16le (sowt / 0x74776F73), 48000 Hz, 1 channels (FL), s16, 768 kb/s
    Stream #0:1: Audio: pcm_s16le (sowt / 0x74776F73), 48000 Hz, 1 channels (FR), s16, 768 kb/s
    Stream #0:2: Video: mpeg2video (m2v1 / 0x3176326D), yuv420p, 720x576 [SAR 16:15 DAR 4:3], q=2-31, 25 fps, 90k tbn, 90k tbc
Stream mapping:
  Stream #0:1 (ac3) -> channelsplit
  channelsplit:FL -> Stream #0:0 (pcm_s16le)
  channelsplit:FR -> Stream #0:1 (pcm_s16le)
  Stream #0:0 -> #0:2 (copy)
Press [q] to stop, [?] for help
frame= 9061 fps=1606 q=-1.0 Lsize=  258633kB time=00:06:02.36 bitrate=5847.0kbits/s    
video:190544kB audio:67890kB subtitle:0 global headers:0kB muxing overhead 0.076662%