nut needs definitions for P016 rawvideo

[Carl Eugen Hoyos]

This is release-critical because fate is currently broken on big-endian.

$ ffmpeg -i fate-suite/lena.pnm -pix_fmt p016 -vframes 1 -vcodec rawvideo out.nut
ffmpeg version N-90220-g69995a9 Copyright (c) 2000-2018 the FFmpeg developers
  built with gcc 6.3.0 (GCC)
  configuration: --enable-gpl
  libavutil      56.  8.100 / 56.  8.100
  libavcodec     58. 13.102 / 58. 13.102
  libavformat    58. 10.100 / 58. 10.100
  libavdevice    58.  2.100 / 58.  2.100
  libavfilter     7. 12.100 /  7. 12.100
  libswscale      5.  0.102 /  5.  0.102
  libswresample   3.  0.101 /  3.  0.101
  libpostproc    55.  0.100 / 55.  0.100
Input #0, ppm_pipe, from 'fate-suite/lena.pnm':
  Duration: N/A, bitrate: N/A
    Stream #0:0: Video: ppm, rgb24, 256x256, 25 tbr, 25 tbn, 25 tbc
Stream mapping:
  Stream #0:0 -> #0:0 (ppm (native) -> rawvideo (native))
Press [q] to stop, [?] for help
Output #0, nut, to 'out.nut':
  Metadata:
    encoder         : Lavf58.10.100
    Stream #0:0: Video: rawvideo (RGB[15] / 0xF424752), p016le, 256x256, q=2-31, 39321 kb/s, 25 fps, 51200 tbn, 25 tbc
    Metadata:
      encoder         : Lavc58.13.102 rawvideo
frame=    1 fps=0.0 q=-0.0 Lsize=     192kB time=00:00:00.00 bitrate=78764400.0kbits/s speed=0.00646x
video:192kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.154114%

$ ffmpeg -i out.nut
ffmpeg version N-90220-g69995a9 Copyright (c) 2000-2018 the FFmpeg developers
  built with gcc 6.3.0 (GCC)
  configuration: --enable-gpl
  libavutil      56.  8.100 / 56.  8.100
  libavcodec     58. 13.102 / 58. 13.102
  libavformat    58. 10.100 / 58. 10.100
  libavdevice    58.  2.100 / 58.  2.100
  libavfilter     7. 12.100 /  7. 12.100
  libswscale      5.  0.102 /  5.  0.102
  libswresample   3.  0.101 /  3.  0.101
  libpostproc    55.  0.100 / 55.  0.100
Input #0, nut, from 'out.nut':
  Metadata:
    encoder         : Lavf58.10.100
  Duration: 00:00:00.00, start: 0.000000, bitrate: N/A
    Stream #0:0: Video: rawvideo (RGB[15] / 0xF424752), rgb555le, 256x256, 25 tbr, 51200 tbn, 51200 tbc
    Metadata:
      encoder         : Lavc58.13.102 rawvideo
At least one output file must be specified

[Carl Eugen Hoyos]

This is not the reason for the fate failure on big-endian but I believe it is a bad idea to use a know-to-be-broken function for regression tests.

[Balling]

See 9fe61b61074b013bc0a9289a207efce2107bfbcf

There should be a way to force it, instead of writing rgb24.