[FFmpeg-user] Question about aresample option "matrix_encoding"

[Bernd Butscheidt]

Hello,

using the option "aresample=matrix_encoding=dplii" I would expect the output to be 2 channels with dolby pro logic encoding, but this seems not to be the case?!
=======================================================



ffmpeg -i 5.1\ Dolby\ Surround\ Test-PqVCPE8_ntE.mkv -vcodec copy -af aresample=matrix_encoding=dplii -acodec ac3 -ab 256k aresample_test.mkv
ffmpeg version n4.1.1 Copyright (c) 2000-2019 the FFmpeg developers
  built with gcc 8.2.1 (GCC) 20181127
  configuration: --prefix=/usr --disable-debug --disable-static --disable-stripping --enable-fontconfig --enable-gmp --enable-gnutls --enable-gpl --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libdrm --enable-libfreetype --enable-libfribidi --enable-libgsm --enable-libiec61883 --enable-libjack --enable-libmodplug --enable-libmp3lame --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libv4l2 --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxcb --enable-libxml2 --enable-libxvid --enable-nvdec --enable-nvenc --enable-omx --enable-shared --enable-version3 --enable-libzvbi --enable-libmysofa
  libavutil      56. 22.100 / 56. 22.100
  libavcodec     58. 35.100 / 58. 35.100
  libavformat    58. 20.100 / 58. 20.100
  libavdevice    58.  5.100 / 58.  5.100
  libavfilter     7. 40.101 /  7. 40.101
  libswscale      5.  3.100 /  5.  3.100
  libswresample   3.  3.100 /  3.  3.100
  libpostproc    55.  3.100 / 55.  3.100
Input #0, matroska,webm, from '5.1 Dolby Surround Test-PqVCPE8_ntE.mkv':
  Metadata:
    ENCODER         : Lavf58.20.100
  Duration: 00:01:22.05, start: 0.000000, bitrate: 1028 kb/s
    Stream #0:0(eng): Video: vp9 (Profile 0), yuv420p(tv, bt709), 1920x1080, SAR 1:1 DAR 16:9, 29.97 fps, 29.97 tbr, 1k tbn, 1k tbc (default)
    Metadata:
      DURATION        : 00:01:21.748000000
    Stream #0:1: Audio: aac (LC), 48000 Hz, 5.1, fltp (default)
    Metadata:
      HANDLER_NAME    : SoundHandler
      DURATION        : 00:01:22.048000000
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
  Stream #0:1 -> #0:1 (aac (native) -> ac3 (native))
Press [q] to stop, [?] for help
Output #0, matroska, to 'aresample_test.mkv':
  Metadata:
    encoder         : Lavf58.20.100
    Stream #0:0(eng): Video: vp9 (Profile 0) (VP90 / 0x30395056), yuv420p(tv, bt709), 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 29.97 fps, 29.97 tbr, 1k tbn, 1k tbc (default)
    Metadata:
      DURATION        : 00:01:21.748000000
    Stream #0:1: Audio: ac3 ([0] [0][0] / 0x2000), 48000 Hz, 5.1, fltp, 256 kb/s (default)
    Metadata:
      HANDLER_NAME    : SoundHandler
      DURATION        : 00:01:22.048000000
      encoder         : Lavc58.35.100 ac3
frame= 2450 fps=0.0 q=-1.0 Lsize=    9012kB time=00:01:22.04 bitrate= 899.9kbits/s speed= 151x    
video:6413kB audio:2564kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.398834%


===============================



Probing the output:

=============================


ffprobe aresample_test.mkv ffprobe version n4.1.1 Copyright (c) 2007-2019 the FFmpeg developers
  built with gcc 8.2.1 (GCC) 20181127
  configuration: --prefix=/usr --disable-debug --disable-static --disable-stripping --enable-fontconfig --enable-gmp --enable-gnutls --enable-gpl --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libdrm --enable-libfreetype --enable-libfribidi --enable-libgsm --enable-libiec61883 --enable-libjack --enable-libmodplug --enable-libmp3lame --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libv4l2 --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxcb --enable-libxml2 --enable-libxvid --enable-nvdec --enable-nvenc --enable-omx --enable-shared --enable-version3 --enable-libzvbi --enable-libmysofa
  libavutil      56. 22.100 / 56. 22.100
  libavcodec     58. 35.100 / 58. 35.100
  libavformat    58. 20.100 / 58. 20.100
  libavdevice    58.  5.100 / 58.  5.100
  libavfilter     7. 40.101 /  7. 40.101
  libswscale      5.  3.100 /  5.  3.100
  libswresample   3.  3.100 /  3.  3.100
  libpostproc    55.  3.100 / 55.  3.100
Input #0, matroska,webm, from 'aresample_test.mkv':
  Metadata:
    ENCODER         : Lavf58.20.100
  Duration: 00:01:22.05, start: 0.000000, bitrate: 899 kb/s
    Stream #0:0(eng): Video: vp9 (Profile 0), yuv420p(tv, bt709), 1920x1080, SAR 1:1 DAR 16:9, 29.97 fps, 29.97 tbr, 1k tbn, 1k tbc (default)
    Metadata:
      DURATION        : 00:01:21.753000000
    Stream #0:1: Audio: ac3, 48000 Hz, 5.1(side), fltp, 256 kb/s (default)
    Metadata:
      HANDLER_NAME    : SoundHandler
      ENCODER         : Lavc58.35.100 ac3

      DURATION        : 00:01:22.048000000

=====================================


The audio stays to has 5.1 channels?!


Kind regards
Bernd B.