[FFmpeg-user] Downmix discrete 5.1 to stereo

[Carles Vila]

Hi, I'm struggling to find the correct command-line for converting 5.1 to
stereo.
My source are 6 x aiff (numbered _1 to _6, corresponding to L, R, C, LFE,
Ls and Rs channels.

My idea is to obtain stereo the way the -ac 2 option does.

Any ideas? Thank you!



ffmpeg -i Test_1.aif -i Test_2.aif -i Test_3.aif -i Test_4.aif -i
Test_5.aif -i Test_6.aif
ffmpeg version 2.7.2 Copyright (c) 2000-2015 the FFmpeg developers
  built with Apple LLVM version 5.1 (clang-503.0.40) (based on LLVM 3.4svn)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/2.7.2_1 --enable-shared
--enable-pthreads --enable-gpl --enable-version3 --enable-hardcoded-tables
--enable-avresample --cc=clang --host-cflags= --host-ldflags=
--enable-opencl --enable-libx264 --enable-libmp3lame --enable-libvo-aacenc
--enable-libxvid --enable-libfreetype --enable-libvorbis --enable-libvpx
--enable-libass --enable-ffplay --enable-libfdk-aac --enable-libopus
--enable-libquvi --enable-libx265 --enable-nonfree --enable-vda

  libavutil      54. 27.100 / 54. 27.100
  libavcodec     56. 41.100 / 56. 41.100
  libavformat    56. 36.100 / 56. 36.100
  libavdevice    56.  4.100 / 56.  4.100
  libavfilter     5. 16.101 /  5. 16.101
  libavresample   2.  1.  0 /  2.  1.  0
  libswscale      3.  1.101 /  3.  1.101
  libswresample   1.  2.100 /  1.  2.100
  libpostproc    53.  3.100 / 53.  3.100
Guessed Channel Layout for  Input Stream #0.0 : mono
Input #0, aiff, from 'Test_1.aif':
  Duration: 00:01:40.38, start: 0.000000, bitrate: 1152 kb/s
    Stream #0:0: Audio: pcm_s24be, 48000 Hz, 1 channels, s32 (24 bit), 1152
kb/s
Guessed Channel Layout for  Input Stream #1.0 : mono
Input #1, aiff, from 'Test_2.aif':
  Duration: 00:01:40.38, start: 0.000000, bitrate: 1152 kb/s
    Stream #1:0: Audio: pcm_s24be, 48000 Hz, 1 channels, s32 (24 bit), 1152
kb/s
Guessed Channel Layout for  Input Stream #2.0 : mono
Input #2, aiff, from 'Test_3.aif':
  Duration: 00:01:40.38, start: 0.000000, bitrate: 1152 kb/s
    Stream #2:0: Audio: pcm_s24be, 48000 Hz, 1 channels, s32 (24 bit), 1152
kb/s
Guessed Channel Layout for  Input Stream #3.0 : mono
Input #3, aiff, from 'Test_4.aif':
  Duration: 00:01:40.38, start: 0.000000, bitrate: 1152 kb/s
    Stream #3:0: Audio: pcm_s24be, 48000 Hz, 1 channels, s32 (24 bit), 1152
kb/s
Guessed Channel Layout for  Input Stream #4.0 : mono
Input #4, aiff, from 'Test_5.aif':
  Duration: 00:01:40.38, start: 0.000000, bitrate: 1152 kb/s
    Stream #4:0: Audio: pcm_s24be, 48000 Hz, 1 channels, s32 (24 bit), 1152
kb/s
Guessed Channel Layout for  Input Stream #5.0 : mono
Input #5, aiff, from 'Test_6.aif':
  Duration: 00:01:40.38, start: 0.000000, bitrate: 1152 kb/s
    Stream #5:0: Audio: pcm_s24be, 48000 Hz, 1 channels, s32 (24 bit), 1152
kb/s
At least one output file must be specified