[FFmpeg-user] Map Only Certain Channels to EBUR128 Filter

[Kieran Hanrahan]

Hello,

Thanks in advance for any replies.  I frequently deal with clips that 
have a 5.1 mix on channels 0-6 and the stereo mix on 7-8.  How could I 
pass just the 5.1 or stereo mix channels to the EBUR128 filter?

Below is my attempt using a filter chain of channelmap and ebur.  I must 
not understand how to use a chain of filters.

ffmpeg -i foo.wav -filter 'channelmap=0|1|2|3|4|5:channel_layout=5.1; 
ebur128' -f null -
ffmpeg version 1.2.1 Copyright (c) 2000-2013 the FFmpeg developers
built on Sep  4 2013 23:36:01 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
[wav @ 0x7f96b2806600] max_analyze_duration 5000000 reached at 5002667 
microseconds
Guessed Channel Layout for  Input Stream #0.0 : 7.1
Input #0, wav, from 'foo.wav':
   Metadata:
     encoded_by      : Autodesk(R) Flame(R) 2013
     date            : 2013-12-18
     creation_time   : 11:55:11
     time_reference  : 192192
     coding_history  :
   Duration: 00:00:24.02, bitrate: 6144 kb/s
     Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz, 
7.1, s16, 6144 kb/s
[channel map filter @ 0x7f96b2bc1400] Key '0|1|2|3|4|5:channel_layout' 
not found.
[AVFilterGraph @ 0x7f96b2423b20] Error initializing filter 'channelmap' 
with args '0|1|2|3|4|5:channel_layout=5.1'
Error opening filters!