[FFmpeg-trac] #3361(undetermined:new): aac_he mono not recogized (reported as stereo)

[FFmpeg]

#3361: aac_he mono not recogized (reported as stereo)
-------------------------------------+-------------------------------------
             Reporter:  blacktrash   |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:               |                  Version:  git-
  undetermined                       |  master
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 Summary of the bug:

 Channel count and channel layout for aac_he mono is always reported
 (decoded?) as stereo.

 How to reproduce:

 {{{
 ffmpeg -i in.aiff -c:a libfdk_aac -profile:a aac_he -b:a 32k -ac 1 fdk-he-
 mono.m4a
 ffmpeg version N-60230-gcfe282e Copyright (c) 2000-2014 the FFmpeg
 developers
   built on Jan 29 2014 14:17:03 with Apple LLVM version 5.0
 (clang-500.2.79) (based on LLVM 3.3svn)
   configuration: --enable-gpl --enable-version3 --enable-nonfree
 --disable-network --disable-ffserver --enable-shared --enable-libfdk-aac
 --enable-libx264 --enable-libxvid --enable-libfaac --enable-libmp3lame
 --enable-libtheora --enable-libvorbis --enable-libvpx --enable-librtmp
 --extra-cflags=-I/sw/include --extra-libs=-L/sw/lib
   libavutil      52. 63.100 / 52. 63.100
   libavcodec     55. 49.101 / 55. 49.101
   libavformat    55. 28.101 / 55. 28.101
   libavdevice    55.  7.100 / 55.  7.100
   libavfilter     4.  1.101 /  4.  1.101
   libswscale      2.  5.101 /  2.  5.101
   libswresample   0. 17.104 /  0. 17.104
   libpostproc    52.  3.100 / 52.  3.100
 Guessed Channel Layout for  Input Stream #0.0 : stereo
 Input #0, aiff, from 'in.aiff':
   Duration: 00:00:30.43, start: 0.000000, bitrate: 1411 kb/s
     Stream #0:0: Audio: pcm_s16le (sowt / 0x74776F73), 44100 Hz, stereo,
 s16, 1411 kb/s
 Output #0, ipod, to 'fdk-he-mono.m4a':
   Metadata:
     encoder         : Lavf55.28.101
     Stream #0:0: Audio: aac (libfdk_aac) (HE-AAC) (mp4a / 0x6134706D),
 44100 Hz, mono, s16, 32 kb/s
 Stream mapping:
   Stream #0:0 -> #0:0 (pcm_s16le -> libfdk_aac)
 Press [q] to stop, [?] for help
 size=     123kB time=00:00:30.44 bitrate=  33.0kbits/s
 video:0kB audio:119kB subtitle:0 global headers:0kB muxing overhead
 2.760628%
 ~/Music/Blacktrash$ ffprobe -show_streams fdk-he-mono.m4a 2>/dev/null |
 fgrep chan
 channels=2
 channel_layout=stereo
 }}}

 Mono in normal profile is recognized correctly:

 {{{
 ffmpeg -i in.aiff -c:a libfdk_aac -b:a 32k -ac 1 fdk-mono.m4a
 ffmpeg version N-60230-gcfe282e Copyright (c) 2000-2014 the FFmpeg
 developers
   built on Jan 29 2014 14:17:03 with Apple LLVM version 5.0
 (clang-500.2.79) (based on LLVM 3.3svn)
   configuration: --enable-gpl --enable-version3 --enable-nonfree
 --disable-network --disable-ffserver --enable-shared --enable-libfdk-aac
 --enable-libx264 --enable-libxvid --enable-libfaac --enable-libmp3lame
 --enable-libtheora --enable-libvorbis --enable-libvpx --enable-librtmp
 --extra-cflags=-I/sw/include --extra-libs=-L/sw/lib
   libavutil      52. 63.100 / 52. 63.100
   libavcodec     55. 49.101 / 55. 49.101
   libavformat    55. 28.101 / 55. 28.101
   libavdevice    55.  7.100 / 55.  7.100
   libavfilter     4.  1.101 /  4.  1.101
   libswscale      2.  5.101 /  2.  5.101
   libswresample   0. 17.104 /  0. 17.104
   libpostproc    52.  3.100 / 52.  3.100
 Guessed Channel Layout for  Input Stream #0.0 : stereo
 Input #0, aiff, from 'in.aiff':
   Duration: 00:00:30.43, start: 0.000000, bitrate: 1411 kb/s
     Stream #0:0: Audio: pcm_s16le (sowt / 0x74776F73), 44100 Hz, stereo,
 s16, 1411 kb/s
 Output #0, ipod, to 'fdk-mono.m4a':
   Metadata:
     encoder         : Lavf55.28.101
     Stream #0:0: Audio: aac (libfdk_aac) (mp4a / 0x6134706D), 44100 Hz,
 mono, s16, 32 kb/s
 Stream mapping:
   Stream #0:0 -> #0:0 (pcm_s16le -> libfdk_aac)
 Press [q] to stop, [?] for help
 size=     125kB time=00:00:30.44 bitrate=  33.7kbits/s
 video:0kB audio:119kB subtitle:0 global headers:0kB muxing overhead
 4.902738%
 ffprobe -show_streams fdk-mono.m4a 2>/dev/null | fgrep chan
 channels=1
 channel_layout=mono
 }}}

 I first believed this was a problem with fdk-aac, but a HE-AAC by iTunes
 yields the same:

 {{{
 $ ffprobe -show_streams itunes-he-mono.m4a 2>/dev/null | fgrep chan
 channels=2
 channel_layout=stereo
 }}}

 See also:
 http://sourceforge.net/p/opencore-amr/mailman/message/31874638/
 ff.
 and:
 https://lists.ffmpeg.org/pipermail/ffmpeg-user/2014-January/019559.html

 Note that profile is always diagnosed as {{{unknown}}}:

 {{{
 ffprobe -show_streams fdk-he-mono.m4a 2>/dev/null | fgrep profile
 profile=unknown
 ffprobe -show_streams fdk-mono.m4a 2>/dev/null | fgrep profile
 profile=unknown
 ffprobe -show_streams itunes-he-mono.m4a 2>/dev/null | fgrep profile
 profile=unknown
 }}}

--
Ticket URL: <https://trac.ffmpeg.org/ticket/3361>
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