[FFmpeg-trac] #6177(undetermined:new): request: use the default bit rate values of afconvert when using audiotoolbox encoding

FFmpeg trac at avcodec.org
Wed Feb 22 11:07:57 EET 2017


#6177: request: use the default bit rate values of afconvert when using
audiotoolbox encoding
-------------------------------------+-------------------------------------
             Reporter:  ponpon       |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:               |                  Version:
  undetermined                       |  unspecified
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 thank you for good apps.

 i think bit rates are too low when not setting {{{-ab}}}.

 For example,
 160kbps is sett in 5.1 of aac by ffmpeg, 224kbps; 7.1ch,
 on the other hand,  320kbps; 5.1ch by afconvert, 448kbps; 7.1ch,

 i request the usage of these.

 5.1ch of aac
 {{{
 ./ffmpeg -y -f lavfi -i aevalsrc=0:d=1:c=5.1 -c:a aac_at test51.mp4 ;
 afconvert -f mp4f -d aac test51.mp4 -o test51.m4a ; mediainfo test51.m4a |
 grep "Nominal bit rate"
 ffmpeg version N-83606-gc9e3952 Copyright (c) 2000-2017 the FFmpeg
 developers
   built with clang version 3.8.1 (tags/RELEASE_381/final)
   configuration: --prefix=/sw --disable-shared --enable-static --enable-
 gpl --enable-version3 --enable-nonfree --enable-pthreads --optflags=-Ofast
 --cc=clang-mp-3.8 --cxx=clang++-mp-3.8 --extra-cflags=' -march=native
 -I/sw/include -I/opt/local/include ' --extra-ldflags=' -L/sw/lib
 -L/opt/local/lib -fopenmp' --extra-ldlibflags='-L/sw/lib -L/opt/local/lib
 -static' --target-os=darwin --arch=x86_64 --cpu=corei7-avx --enable-
 avresample --enable-libfdk-aac --enable-libmp3lame --enable-
 libopencore_amrnb --enable-libopencore_amrwb --enable-libopenjpeg
 --enable-libopus --enable-libspeex --enable-libtheora --enable-libvorbis
 --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libxvid
 --enable-libfreetype --enable-openssl --enable-gnutls --enable-gcrypt
 --enable-gmp --enable-librtmp --enable-libass --enable-fontconfig
 --enable-libfribidi --enable-libbluray --enable-libdc1394 --enable-
 libschroedinger --enable-libmodplug --enable-lzma --enable-libx264
 --enable-libx265 --enable-libzimg --enable-libvidstab --enable-libsoxr
 --enable-opengl --enable-opencl --pkg-config-flags=' --libs --static'
   libavutil      55. 47.100 / 55. 47.100
   libavcodec     57. 80.101 / 57. 80.101
   libavformat    57. 66.102 / 57. 66.102
   libavdevice    57.  2.100 / 57.  2.100
   libavfilter     6. 73.100 /  6. 73.100
   libavresample   3.  2.  0 /  3.  2.  0
   libswscale      4.  3.101 /  4.  3.101
   libswresample   2.  4.100 /  2.  4.100
   libpostproc    54.  2.100 / 54.  2.100
 Input #0, lavfi, from 'aevalsrc=0:d=1:c=5.1':
   Duration: N/A, start: 0.000000, bitrate: 16934 kb/s
     Stream #0:0: Audio: pcm_f64le, 44100 Hz, 5.1, dbl, 16934 kb/s
 [aac_at @ 0x7fb2b703b000] Bitrate 128000 not allowed; changing to 160000
 Output #0, mp4, to 'test51.mp4':
   Metadata:
     encoder         : Lavf57.66.102
     Stream #0:0: Audio: aac (aac_at) ([64][0][0][0] / 0x0040), 44100 Hz,
 5.1(side), s16, 128 kb/s
     Metadata:
       encoder         : Lavc57.80.101 aac_at
 Stream mapping:
   Stream #0:0 -> #0:0 (pcm_f64le (native) -> aac (aac_at))
 Press [q] to stop, [?] for help
 size=      22kB time=00:00:01.04 bitrate= 171.9kbits/s speed=39.6x
 video:0kB audio:21kB subtitle:0kB other streams:0kB global headers:0kB
 muxing overhead: 4.365024%
 *** warning: Transcoding multichannel audio may not handle channel layouts
 correctly (0)
 Nominal bit rate                         : 320 Kbps
 }}}

 7.1ch
 {{{
 ./ffmpeg -y -f lavfi -i aevalsrc=0:d=1:c=7.1 -c:a aac_at test71.mp4 ;
 afconvert -f mp4f -d aac test71.mp4 -o test71.m4a ; mediainfo test71.m4a |
 grep "Nominal bit rate"
 ffmpeg version N-83606-gc9e3952 Copyright (c) 2000-2017 the FFmpeg
 developers
   built with clang version 3.8.1 (tags/RELEASE_381/final)
   configuration: --prefix=/sw --disable-shared --enable-static --enable-
 gpl --enable-version3 --enable-nonfree --enable-pthreads --optflags=-Ofast
 --cc=clang-mp-3.8 --cxx=clang++-mp-3.8 --extra-cflags=' -march=native
 -I/sw/include -I/opt/local/include ' --extra-ldflags=' -L/sw/lib
 -L/opt/local/lib -fopenmp' --extra-ldlibflags='-L/sw/lib -L/opt/local/lib
 -static' --target-os=darwin --arch=x86_64 --cpu=corei7-avx --enable-
 avresample --enable-libfdk-aac --enable-libmp3lame --enable-
 libopencore_amrnb --enable-libopencore_amrwb --enable-libopenjpeg
 --enable-libopus --enable-libspeex --enable-libtheora --enable-libvorbis
 --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libxvid
 --enable-libfreetype --enable-openssl --enable-gnutls --enable-gcrypt
 --enable-gmp --enable-librtmp --enable-libass --enable-fontconfig
 --enable-libfribidi --enable-libbluray --enable-libdc1394 --enable-
 libschroedinger --enable-libmodplug --enable-lzma --enable-libx264
 --enable-libx265 --enable-libzimg --enable-libvidstab --enable-libsoxr
 --enable-opengl --enable-opencl --pkg-config-flags=' --libs --static'
   libavutil      55. 47.100 / 55. 47.100
   libavcodec     57. 80.101 / 57. 80.101
   libavformat    57. 66.102 / 57. 66.102
   libavdevice    57.  2.100 / 57.  2.100
   libavfilter     6. 73.100 /  6. 73.100
   libavresample   3.  2.  0 /  3.  2.  0
   libswscale      4.  3.101 /  4.  3.101
   libswresample   2.  4.100 /  2.  4.100
   libpostproc    54.  2.100 / 54.  2.100
 Input #0, lavfi, from 'aevalsrc=0:d=1:c=7.1':
   Duration: N/A, start: 0.000000, bitrate: 22579 kb/s
     Stream #0:0: Audio: pcm_f64le, 44100 Hz, 7.1, dbl, 22579 kb/s
 [aac_at @ 0x7f95c3853e00] Bitrate 128000 not allowed; changing to 224000
 Output #0, mp4, to 'test71.mp4':
   Metadata:
     encoder         : Lavf57.66.102
     Stream #0:0: Audio: aac (aac_at) ([64][0][0][0] / 0x0040), 44100 Hz,
 7.0, s16, 128 kb/s
     Metadata:
       encoder         : Lavc57.80.101 aac_at
 Stream mapping:
   Stream #0:0 -> #0:0 (pcm_f64le (native) -> aac (aac_at))
 Press [q] to stop, [?] for help
 size=      30kB time=00:00:01.04 bitrate= 237.9kbits/s speed=  34x
 video:0kB audio:29kB subtitle:0kB other streams:0kB global headers:0kB
 muxing overhead: 3.144424%
 *** warning: Transcoding multichannel audio may not handle channel layouts
 correctly (0)
 Nominal bit rate                         : 448 Kbps
 }}}

--
Ticket URL: <https://trac.ffmpeg.org/ticket/6177>
FFmpeg <https://ffmpeg.org>
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