mv30 decoder renders video upside down

[pross]

Steps to reproduce

% ffplay ​http://samples.ffmpeg.org/V-codecs/mv30.avi

car drives upside down

% ffplay mv30-test-columbia.avi

columbia text is upside down

[Elon Musk]

This is how virtual dub renders it. So not really bug.

[Carl Eugen Hoyos]

There may be no bug in libavcodec, but the issue is definitely reproducible with the application.

$ ffmpeg -i mv30-test-columbia.avi out.avi
ffmpeg version N-97298-g9f4054a0cb Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 9 (SUSE Linux)
  configuration: --enable-gpl --enable-gnutls --enable-libx264 --enable-libx265 --enable-libdav1d --enable-libvpx --enable-libopus --enable-libxml2 --enable-libwebp --enable-librav1e --extra-cflags=-I/usr/include/rav1e --enable-opencl --enable-chromaprint
  libavutil      56. 42.102 / 56. 42.102
  libavcodec     58. 78.101 / 58. 78.101
  libavformat    58. 42.100 / 58. 42.100
  libavdevice    58.  9.103 / 58.  9.103
  libavfilter     7. 77.101 /  7. 77.101
  libswscale      5.  6.101 /  5.  6.101
  libswresample   3.  6.100 /  3.  6.100
  libpostproc    55.  6.100 / 55.  6.100
Input #0, avi, from 'mv30-test-columbia.avi':
  Duration: 00:00:06.00, start: 0.000000, bitrate: 1157 kb/s
    Stream #0:0: Video: mv30 (MV30 / 0x3033564D), yuv420p(pc), 320x128, 1164 kb/s, 10 fps, 10 tbr, 10 tbn, 10 tbc
Stream mapping:
  Stream #0:0 -> #0:0 (mv30 (native) -> mpeg4 (native))
Press [q] to stop, [?] for help
[mpeg4 @ 0x25e4200] too many threads/slices (9), reducing to 8
Output #0, avi, to 'out.avi':
  Metadata:
    ISFT            : Lavf58.42.100
    Stream #0:0: Video: mpeg4 (FMP4 / 0x34504D46), yuv420p, 320x128, q=2-31, 200 kb/s, 10 fps, 10 tbn, 10 tbc
    Metadata:
      encoder         : Lavc58.78.101 mpeg4
    Side data:
      cpb: bitrate max/min/avg: 0/0/200000 buffer size: 0 vbv_delay: N/A
frame=   60 fps=0.0 q=3.1 Lsize=     228kB time=00:00:06.00 bitrate= 310.7kbits/s speed= 131x    
video:221kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 3.166844%

[ami_stuff]

This problem doesn't seem to be related only to VirtualDub. The same thing happens with avi files exported from Premiere - such files plays correctly with VFW-based players, but decodes upside-down with FFmpeg.