[FFmpeg-trac] #929(avcodec:open): AAC decoder does not respect request_channels (was: AAC 5.1 channel decoding issue)

[FFmpeg]

#929: AAC decoder does not respect request_channels
-------------------------------------+-----------------------------------
             Reporter:  kaijun61     |                    Owner:
                 Type:  enhancement  |                   Status:  open
             Priority:  wish         |                Component:  avcodec
              Version:  git-master   |               Resolution:
             Keywords:  AAC          |               Blocked By:
             Blocking:               |  Reproduced by developer:  1
Analyzed by developer:  0            |
-------------------------------------+-----------------------------------
Changes (by cehoyos):

 * priority:  normal => wish
 * status:  new => open
 * type:  defect => enhancement
 * reproduced:  0 => 1


Comment:

 This works at least for ac-3 and eac-3.
 {{{
 $ ffmpeg -request_channels 1 -i fate-suite/aac/al_sbr_cm_48_5.1.mp4
 out.wav
 ffmpeg version N-37197-ga8ae00b Copyright (c) 2000-2012 the FFmpeg
 developers
   built on Jan 27 2012 00:29:41 with gcc 4.5.3
   configuration: --cc=/usr/local/gcc-4.5.3/bin/gcc
   libavutil      51. 34.101 / 51. 34.101
   libavcodec     53. 60.100 / 53. 60.100
   libavformat    53. 31.100 / 53. 31.100
   libavdevice    53.  4.100 / 53.  4.100
   libavfilter     2. 60.100 /  2. 60.100
   libswscale      2.  1.100 /  2.  1.100
   libswresample   0.  6.100 /  0.  6.100
 Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'fate-
 suite/aac/al_sbr_cm_48_5.1.mp4':
   Metadata:
     major_brand     : mp42
     minor_version   : 0
     compatible_brands: mp42isom
     creation_time   : 2008-01-22 11:26:59
   Duration: 00:00:32.17, start: 0.000000, bitrate: 129 kb/s
     Stream #0:0(und): Audio: aac (mp4a / 0x6134706D), 48000 Hz, 6
 channels, s16, 128 kb/s
     Metadata:
       creation_time   : 2008-01-22 11:26:59
       handler_name    : soun
 Output #0, wav, to 'out.wav':
   Metadata:
     major_brand     : mp42
     minor_version   : 0
     compatible_brands: mp42isom
     creation_time   : 2008-01-22 11:26:59
     encoder         : Lavf53.31.100
     Stream #0:0(und): Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz,
 6 channels, s16, 4608 kb/s
     Metadata:
       creation_time   : 2008-01-22 11:26:59
       handler_name    : soun
 Stream mapping:
   Stream #0:0 -> #0:0 (aac -> pcm_s16le)
 Press [q] to stop, [?] for help
 size=   18096kB time=00:00:32.17 bitrate=4608.0kbits/s
 video:0kB audio:18096kB global headers:0kB muxing overhead 0.000248%
 }}}

-- 
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/929#comment:14>
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