$ ffmpeg -i bbb_sunflower_native_60fps_normal.mp4 -ss 00:00:00.0 -t 00:00:05.0 -c:a libfdk_aac -b:a 256k -af "channelmap=channel_layout=stereo" -compression_level 10 -vn -f mp4 -dash 1 test_a_aac256ks.mp4
ffmpeg version 3.4 Copyright (c) 2000-2017 the FFmpeg developers
  built with Apple LLVM version 9.0.0 (clang-900.0.38)
  configuration: --prefix=/opt/local --enable-swscale --enable-avfilter --enable-avresample --enable-libmp3lame --enable-libvorbis --enable-libopus --enable-librsvg --enable-libtheora --enable-libopenjpeg --enable-libmodplug --enable-libvpx --enable-libsoxr --enable-libspeex --enable-libass --enable-libbluray --enable-lzma --enable-gnutls --enable-fontconfig --enable-libfreetype --enable-libfribidi --disable-indev=jack --disable-outdev=xv --enable-audiotoolbox --enable-sdl2 --mandir=/opt/local/share/man --enable-shared --enable-pthreads --cc=/usr/bin/clang --enable-videotoolbox --arch=x86_64 --enable-x86asm --enable-libx265 --enable-gpl --enable-postproc --enable-libx264 --enable-libxvid --enable-version3 --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libsmbclient --enable-nonfree --enable-libfdk-aac
  libavutil      55. 78.100 / 55. 78.100
  libavcodec     57.107.100 / 57.107.100
  libavformat    57. 83.100 / 57. 83.100
  libavdevice    57. 10.100 / 57. 10.100
  libavfilter     6.107.100 /  6.107.100
  libavresample   3.  7.  0 /  3.  7.  0
  libswscale      4.  8.100 /  4.  8.100
  libswresample   2.  9.100 /  2.  9.100
  libpostproc    54.  7.100 / 54.  7.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'bbb_sunflower_native_60fps_normal.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 1
    compatible_brands: isomavc1
    creation_time   : 2013-12-24T11:10:47.000000Z
    title           : Big Buck Bunny, Sunflower version
    artist          : Blender Foundation 2008, Janus Bager Kristensen 2013
    comment         : Creative Commons Attribution 3.0 - http://bbb3d.renderfarming.net
    genre           : Animation
    composer        : Sacha Goedegebure
  Duration: 00:10:34.53, start: 0.000000, bitrate: 10487 kb/s
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 4000x2250 [SAR 1:1 DAR 16:9], 10002 kb/s, 60 fps, 60 tbr, 60k tbn, 120 tbc (default)
    Metadata:
      creation_time   : 2013-12-24T11:10:47.000000Z
      handler_name    : GPAC ISO Video Handler
    Stream #0:1(und): Audio: mp3 (mp4a / 0x6134706D), 48000 Hz, stereo, s16p, 160 kb/s (default)
    Metadata:
      creation_time   : 2013-12-24T11:10:49.000000Z
      handler_name    : GPAC ISO Audio Handler
    Stream #0:2(und): Audio: ac3 (ac-3 / 0x332D6361), 48000 Hz, 5.1(side), fltp, 320 kb/s (default)
    Metadata:
      creation_time   : 2013-12-24T11:10:49.000000Z
      handler_name    : GPAC ISO Audio Handler
    Side data:
      audio service type: main
Stream mapping:
  Stream #0:2 -> #0:0 (ac3 (native) -> aac (libfdk_aac))
Press [q] to stop, [?] for help
Output #0, mp4, to 'test_a_aac256ks.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 1
    compatible_brands: isomavc1
    composer        : Sacha Goedegebure
    title           : Big Buck Bunny, Sunflower version
    artist          : Blender Foundation 2008, Janus Bager Kristensen 2013
    comment         : Creative Commons Attribution 3.0 - http://bbb3d.renderfarming.net
    genre           : Animation
    encoder         : Lavf57.83.100
    Stream #0:0(und): Audio: aac (libfdk_aac) (mp4a / 0x6134706D), 48000 Hz, stereo, s16, 256 kb/s (default)
    Metadata:
      creation_time   : 2013-12-24T11:10:49.000000Z
      handler_name    : GPAC ISO Audio Handler
      encoder         : Lavc57.107.100 libfdk_aac
    Side data:
      audio service type: main
size=     160kB time=00:00:05.01 bitrate= 261.4kbits/s speed=27.5x
video:0kB audio:158kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 1.265815%

$ ffmpeg -f webm_dash_manifest -i test_a_aac256ks.mp4 -c copy -map 0 -f webm_dash_manifest -adaptation_sets "id=0,streams=0" test_a.mpd
ffmpeg version 3.4 Copyright (c) 2000-2017 the FFmpeg developers
  built with Apple LLVM version 9.0.0 (clang-900.0.38)
  configuration: --prefix=/opt/local --enable-swscale --enable-avfilter --enable-avresample --enable-libmp3lame --enable-libvorbis --enable-libopus --enable-librsvg --enable-libtheora --enable-libopenjpeg --enable-libmodplug --enable-libvpx --enable-libsoxr --enable-libspeex --enable-libass --enable-libbluray --enable-lzma --enable-gnutls --enable-fontconfig --enable-libfreetype --enable-libfribidi --disable-indev=jack --disable-outdev=xv --enable-audiotoolbox --enable-sdl2 --mandir=/opt/local/share/man --enable-shared --enable-pthreads --cc=/usr/bin/clang --enable-videotoolbox --arch=x86_64 --enable-x86asm --enable-libx265 --enable-gpl --enable-postproc --enable-libx264 --enable-libxvid --enable-version3 --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libsmbclient --enable-nonfree --enable-libfdk-aac
  libavutil      55. 78.100 / 55. 78.100
  libavcodec     57.107.100 / 57.107.100
  libavformat    57. 83.100 / 57. 83.100
  libavdevice    57. 10.100 / 57. 10.100
  libavfilter     6.107.100 /  6.107.100
  libavresample   3.  7.  0 /  3.  7.  0
  libswscale      4.  8.100 /  4.  8.100
  libswresample   2.  9.100 /  2.  9.100
  libpostproc    54.  7.100 / 54.  7.100
[webm_dash_manifest @ 0x7f862c800a00] Read error at pos. 1 (0x1)
[webm_dash_manifest @ 0x7f862c800a00] EBML header parsing failed
[webm_dash_manifest @ 0x7f862c800a00] Failed to read file headers
test_a_aac256ks.mp4: Operation not permitted