[FFmpeg-devel] [PATCH] libavutil: add clean aperture (CLAP) side data.

[Kieran O Leary]

Hi Neil,

Thanks so much for working on this - what was the impetus?
I started the ticket you mentioned. I applied your patch and tested it with
the clap.mov file from that ticket. How do I know if behaviour has changed
with this patch, how should I be testing?
I don't see any reference to the clap atom values when transcoding the file
to MKV or to another mov:

./ffmpeg -i /mnt/c/Users/kieran.oleary/Downloads/clap.mov out.mkv
ffmpeg version N-97506-g2fae000994 Copyright (c) 2000-2020 the FFmpeg
developers
  built with gcc 7 (Ubuntu 7.5.0-3ubuntu1~18.04)
  configuration:
  libavutil      56. 43.100 / 56. 43.100
  libavcodec     58. 82.100 / 58. 82.100
  libavformat    58. 42.101 / 58. 42.101
  libavdevice    58.  9.103 / 58.  9.103
  libavfilter     7. 79.100 /  7. 79.100
  libswscale      5.  6.101 /  5.  6.101
  libswresample   3.  6.100 /  3.  6.100
Guessed Channel Layout for Input Stream #0.1 : stereo
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from
'/mnt/c/Users/kieran.oleary/Downloads/clap.mov':
  Metadata:
    major_brand     : qt
    minor_version   : 537199360
    compatible_brands: qt
    creation_time   : 2018-09-13T08:48:41.000000Z
  Duration: 00:00:01.00, start: 0.000000, bitrate: 80686 kb/s
    Stream #0:0(eng): Video: v210 (v210 / 0x30313276),
yuv422p10le(smpte170m/bt470bg/bt709, top coded first (swapped)), 720x576,
79626 kb/s, SAR 59:54 DAR 295:216, 9 fps, 25 tbr, 25k tbn, 25k tbc (default)
    Metadata:
      creation_time   : 2018-09-13T08:48:41.000000Z
      handler_name    : ?Apple Video Media Handler
      encoder         : Uncompressed 10-Bit YUV
      timecode        : 00:00:00:00
    Stream #0:1(eng): Audio: pcm_s24le (in24 / 0x34326E69), 48000 Hz,
stereo, s32 (24 bit), 2304 kb/s (default)
    Metadata:
      creation_time   : 2018-09-13T08:48:41.000000Z
      handler_name    : ?Apple Sound Media Handler
      timecode        : 00:00:00:00
    Stream #0:2(eng): Data: none (tmcd / 0x64636D74), 0 kb/s (default)
    Metadata:
      creation_time   : 2018-09-13T08:48:41.000000Z
      handler_name    : Time Code Media Handler
      reel_name       : 001
      timecode        : 00:00:00:00
File 'out.mkv' already exists. Overwrite? [y/N] y
Stream mapping:
  Stream #0:0 -> #0:0 (v210 (native) -> mpeg4 (native))
  Stream #0:1 -> #0:1 (pcm_s24le (native) -> ac3 (native))
Press [q] to stop, [?] for help
Output #0, matroska, to 'out.mkv':
  Metadata:
    major_brand     : qt
    minor_version   : 537199360
    compatible_brands: qt
    encoder         : Lavf58.42.101
    Stream #0:0(eng): Video: mpeg4 (FMP4 / 0x34504D46), yuv420p(top coded
first (swapped)), 720x576 [SAR 59:54 DAR 295:216], q=2-31, 200 kb/s, 25
fps, 1k tbn, 25 tbc (default)
    Metadata:
      creation_time   : 2018-09-13T08:48:41.000000Z
      handler_name    : ?Apple Video Media Handler
      timecode        : 00:00:00:00
      encoder         : Lavc58.82.100 mpeg4
    Side data:
      cpb: bitrate max/min/avg: 0/0/200000 buffer size: 0 vbv_delay: N/A
    Stream #0:1(eng): Audio: ac3 ([0] [0][0] / 0x2000), 48000 Hz, stereo,
fltp (24 bit), 192 kb/s (default)
    Metadata:
      creation_time   : 2018-09-13T08:48:41.000000Z
      handler_name    : ?Apple Sound Media Handler
      timecode        : 00:00:00:00
      encoder         : Lavc58.82.100 ac3
frame=    9 fps=0.0 q=1.6 Lsize=      36kB time=00:00:00.41 bitrate=
717.1kbits/s speed=9.05x
video:25kB audio:10kB subtitle:0kB other streams:0kB global headers:0kB
muxing overhead: 3.596637%