ffmpeg -i "input.mkv" -map 0:0 -map 0:2 -map 0:2 -c:v copy -c:a:0 aac -ac:a:0 2 -af:a:0 "pan=stereo|FL=FC+0.30*FL+0.30*BL|FR=FC+0.30*FR+0.30*BR" -c:a:1 copy "output.mkv"
ffmpeg version N-86175-g64ea4d1 Copyright (c) 2000-2017 the FFmpeg developers
  built with gcc 6.3.0 (GCC)
  configuration: --enable-gpl --enable-version3 --enable-cuda --enable-cuvid --enable-d3d11va --enable-dxva2 --enable-libmfx --enable-nvenc --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenh264 --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-libzimg --enable-lzma --enable-zlib
  libavutil      55. 63.100 / 55. 63.100
  libavcodec     57. 96.101 / 57. 96.101
  libavformat    57. 72.101 / 57. 72.101
  libavdevice    57.  7.100 / 57.  7.100
  libavfilter     6. 90.100 /  6. 90.100
  libswscale      4.  7.101 /  4.  7.101
  libswresample   2.  8.100 /  2.  8.100
  libpostproc    54.  6.100 / 54.  6.100
Input #0, matroska,webm, from 'input.mkv':
  Metadata:
    ENCODER         : Lavf57.72.101
  Duration: 02:22:09.49, start: 0.000000, bitrate: 2595 kb/s
    Stream #0:0: Video: hevc (Main 10), yuv420p10le(tv), 1920x816, SAR 1:1 DAR 40:17, 23.98 fps, 23.98 tbr, 1k tbn, 23.98 tbc (default)
    Metadata:
      BPS             : 1957560
      BPS-eng         : 1957560
      DURATION-eng    : 02:22:09.480000000
      NUMBER_OF_FRAMES: 204503
      NUMBER_OF_FRAMES-eng: 204503
      NUMBER_OF_BYTES : 2087121591
      NUMBER_OF_BYTES-eng: 2087121591
      _STATISTICS_WRITING_APP: mkvmerge v9.0.1 ('Obstacles') 64bit
      _STATISTICS_WRITING_APP-eng: mkvmerge v9.0.1 ('Obstacles') 64bit
      _STATISTICS_WRITING_DATE_UTC: 2016-06-19 03:07:15
      _STATISTICS_WRITING_DATE_UTC-eng: 2016-06-19 03:07:15
      _STATISTICS_TAGS: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES
      _STATISTICS_TAGS-eng: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES
      DURATION        : 02:22:09.480000000
    Stream #0:1: Audio: aac (LC), 48000 Hz, stereo, fltp
    Metadata:
      BPS             : 438422
      BPS-eng         : 438422
      DURATION-eng    : 02:22:09.472000000
      NUMBER_OF_FRAMES: 399819
      NUMBER_OF_FRAMES-eng: 399819
      NUMBER_OF_BYTES : 467438758
      NUMBER_OF_BYTES-eng: 467438758
      _STATISTICS_WRITING_APP: mkvmerge v9.0.1 ('Obstacles') 64bit
      _STATISTICS_WRITING_APP-eng: mkvmerge v9.0.1 ('Obstacles') 64bit
      _STATISTICS_WRITING_DATE_UTC: 2016-06-19 03:07:15
      _STATISTICS_WRITING_DATE_UTC-eng: 2016-06-19 03:07:15
      _STATISTICS_TAGS: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES
      _STATISTICS_TAGS-eng: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES
      ENCODER         : Lavc57.96.101 aac
      DURATION        : 02:22:09.491000000
    Stream #0:2: Audio: aac (LC), 48000 Hz, 5.1, fltp
    Metadata:
      BPS             : 438422
      BPS-eng         : 438422
      DURATION-eng    : 02:22:09.472000000
      NUMBER_OF_FRAMES: 399819
      NUMBER_OF_FRAMES-eng: 399819
      NUMBER_OF_BYTES : 467438758
      NUMBER_OF_BYTES-eng: 467438758
      _STATISTICS_WRITING_APP: mkvmerge v9.0.1 ('Obstacles') 64bit
      _STATISTICS_WRITING_APP-eng: mkvmerge v9.0.1 ('Obstacles') 64bit
      _STATISTICS_WRITING_DATE_UTC: 2016-06-19 03:07:15
      _STATISTICS_WRITING_DATE_UTC-eng: 2016-06-19 03:07:15
      _STATISTICS_TAGS: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES
      _STATISTICS_TAGS-eng: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES
      DURATION        : 02:22:09.492000000
Filtergraph 'pan=stereo|FL=FC+0.30*FL+0.30*BL|FR=FC+0.30*FR+0.30*BR' was defined for audio output stream 0:2 but codec copy was selected.
Filtering and streamcopy cannot be used together.