rv60: visible artefacts 2

[ami_stuff]

attached file decodes correctly with RealPlayer Converter and the output video has 1000x1000 resolution

./ffmpeg -i i10_2_25.rmhd -y out.avi
ffmpeg version N-117708-g8503c64aa8 Copyright (c) 2000-2024 the FFmpeg developers
  built with gcc 11 (Ubuntu 11.4.0-1ubuntu1~22.04)
  configuration: 
  libavutil      59. 46.100 / 59. 46.100
  libavcodec     61. 24.100 / 61. 24.100
  libavformat    61.  9.100 / 61.  9.100
  libavdevice    61.  4.100 / 61.  4.100
  libavfilter    10.  6.101 / 10.  6.101
  libswscale      8.  9.101 /  8.  9.101
  libswresample   5.  4.100 /  5.  4.100
Input #0, rm, from 'i10_2_25.rmhd':
  Duration: 00:00:10.00, start: 0.000000, bitrate: 708 kb/s
  Stream #0:0: Video: rv60 (RV60 / 0x30365652), yuv420p, 1000x1000, 705 kb/s, 24 fps, 24 tbr, 1k tbn
Stream mapping:
  Stream #0:0 -> #0:0 (rv60 (native) -> mpeg4 (native))
Press [q] to stop, [?] for help
[rv60 @ 0x55d6cf94e280] changing dimensions to 748x748
Output #0, avi, to 'out.avi':
  Metadata:
    ISFT            : Lavf61.9.100
  Stream #0:0: Video: mpeg4 (FMP4 / 0x34504D46), yuv420p(tv, progressive), 748x748, q=2-31, 200 kb/s, 24 fps, 24 tbn
    Metadata:
      encoder         : Lavc61.24.100 mpeg4
    Side data:
      cpb: bitrate max/min/avg: 0/0/200000 buffer size: 0 vbv_delay: N/A
frame=  210 fps=0.0 q=31.0 size=     768KiB time=00:00:08.75 bitrate= 719.0kbits[out#0/avi @ 0x55d6cf940440] video:913KiB audio:0KiB subtitle:0KiB other streams:0KiB global headers:0KiB muxing overhead: 1.240220%
frame=  241 fps=0.0 q=31.0 Lsize=     925KiB time=00:00:10.04 bitrate= 754.3kbits/s speed=  17x    

[ami_stuff]

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