isom little-endian audio detected as big-endian

[Carl Eugen Hoyos]

​https://forum.handbrake.fr/viewtopic.php?f=5&t=38129
HandBrake forum user arichards1 provided a sample file that produces broken audio with FFmpeg, regression since 152e9a43f2435e6f2cdaf50ad0605e951c774386

$ ffmpeg -i Blackmagic\ HyperDeck\ Studio\ Mini\[0013\]_cut.mp4
ffmpeg version N-91666-g70d2bab Copyright (c) 2000-2018 the FFmpeg developers
  built with gcc 6.4.0 (GCC)
  configuration: --enable-gpl --enable-gnutls --enable-libxml2
  libavutil      56. 19.100 / 56. 19.100
  libavcodec     58. 24.101 / 58. 24.101
  libavformat    58. 17.103 / 58. 17.103
  libavdevice    58.  4.101 / 58.  4.101
  libavfilter     7. 26.100 /  7. 26.100
  libswscale      5.  2.100 /  5.  2.100
  libswresample   3.  2.100 /  3.  2.100
  libpostproc    55.  2.100 / 55.  2.100
Guessed Channel Layout for Input Stream #0.1 : stereo
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'Blackmagic HyperDeck Studio Mini[0013]_cut.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 1
    compatible_brands: iso4avc1isom
    creation_time   : 2018-07-15T20:18:01.000000Z
  Duration: 00:04:36.48, start: 0.000000, bitrate: 74 kb/s
    Stream #0:0(eng): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv, bt709, progressive), 1920x1080, 19999 kb/s, SAR 1:1 DAR 16:9, 50 fps, 50 tbr, 50 tbn, 100 tbc (default)
    Metadata:
      creation_time   : 2018-07-15T20:18:01.000000Z
      handler_name    : ?Apple Video Media Handler
      encoder         : H264/AVC
      timecode        : 00:00:00:00
    Stream #0:1(eng): Audio: pcm_s24be (in24 / 0x34326E69), 48000 Hz, stereo, s32 (24 bit), 2304 kb/s (default)
    Metadata:
      creation_time   : 2018-07-15T20:18:01.000000Z
      handler_name    : ?Apple Sound Media Handler
      timecode        : 00:00:00:00
    Stream #0:2(eng): Data: none (tmcd / 0x64636D74) (default)
    Metadata:
      creation_time   : 2018-07-15T20:18:01.000000Z
      handler_name    : ?Time Code Media Handler
      timecode        : 00:00:00:00
At least one output file must be specified

Audio is actually little-endia pcm_s24le.
The stsd atom has version 1, contains a wave and an enda atom but they are not found because the 16 specific version 1 bytes are not read for brand isom and the stsd atom is not consumed correctly.
Works fine with every (?) other demuxer, I couldn't find testclip_wrong_version_1_audio_stsd.mp4.

[Carl Eugen Hoyos]

Fixed by Justin in d2047c14c0789ce3059b840472fb96fd8bd854a9