vmix: first frame decodes with artefacts

[ami_stuff]

./ffmpeg -i vmix.avi -frames:v 1 -y out.bmp
ffmpeg version N-112010-g1a87a9d82a Copyright (c) 2000-2023 the FFmpeg developers
  built with gcc 11 (Ubuntu 11.4.0-1ubuntu1~22.04)
  configuration: 
  libavutil      58. 19.100 / 58. 19.100
  libavcodec     60. 26.100 / 60. 26.100
  libavformat    60. 11.100 / 60. 11.100
  libavdevice    60.  2.101 / 60.  2.101
  libavfilter     9. 11.100 /  9. 11.100
  libswscale      7.  3.100 /  7.  3.100
  libswresample   4. 11.100 /  4. 11.100
Input #0, avi, from 'vmix.avi':
  Metadata:
    software        : Lavf58.76.100
  Duration: 00:00:00.52, start: 0.000000, bitrate: 21950 kb/s
  Stream #0:0: Video: vmix (VMX1 / 0x31584D56), yuv422p, 640x360, 22579 kb/s, 60 fps, 60 tbr, 60 tbn
Stream mapping:
  Stream #0:0 -> #0:0 (vmix (native) -> bmp (native))
Press [q] to stop, [?] for help
Output #0, image2, to 'out.bmp':
  Metadata:
    software        : Lavf58.76.100
    encoder         : Lavf60.11.100
  Stream #0:0: Video: bmp, bgr24(pc, gbr/unknown/unknown, progressive), 640x360, q=2-31, 200 kb/s, 60 fps, 60 tbn
    Metadata:
      encoder         : Lavc60.26.100 bmp
frame=    0 fps=0.0 q=-0.0 size=       0kB time=00:00:00.00 bitrate=N/A speed=  [image2 @ 0x5556c69a5740] The specified filename 'out.bmp' does not contain an image sequence pattern or a pattern is invalid.
[image2 @ 0x5556c69a5740] Use a pattern such as %03d for an image sequence or use the -update option (with -frames:v 1 if needed) to write a single image.
[out#0/image2 @ 0x5556c69a6b40] video:675kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
frame=    1 fps=0.0 q=-0.0 Lsize=N/A time=00:00:00.00 bitrate=N/A speed=   0x

[Elon Musk]

Probably fixed in 5acc3c4cff88de1ced1c4d9c6070b708613b43c1