Artefacts in MPEG-4 ASP elementary stream

[cehoyos]

I will upload an ASP elementary streams that shows accumulating artefacts with ffmpeg, plays fine with mplayer -vc xvid -demuxer lavf (-demuxer mpeg4es produces different artefacts).

$ ffmpeg -i tears.m4v -ss 9.65 out.png
ffmpeg version N-48881-g7980cca Copyright (c) 2000-2013 the FFmpeg developers
  built on Jan 14 2013 17:11:14 with gcc 4.7 (SUSE Linux)
  configuration: --enable-gpl --disable-indev=jack
  libavutil      52. 14.100 / 52. 14.100
  libavcodec     54. 89.100 / 54. 89.100
  libavformat    54. 59.107 / 54. 59.107
  libavdevice    54.  3.102 / 54.  3.102
  libavfilter     3. 32.100 /  3. 32.100
  libswscale      2.  1.103 /  2.  1.103
  libswresample   0. 17.102 /  0. 17.102
  libpostproc    52.  2.100 / 52.  2.100
[m4v @ 0x2bcbde0] Estimating duration from bitrate, this may be inaccurate
Input #0, m4v, from 'tears.m4v':
  Duration: N/A, start: 0.000000, bitrate: N/A
    Stream #0:0: Video: mpeg4, yuv420p, 640x480 [SAR 1:1 DAR 4:3], 29.97 tbr, 1200k tbn, 30k tbc
Output #0, image2, to 'out.png':
  Metadata:
    encoder         : Lavf54.59.107
    Stream #0:0: Video: png, rgb24, 640x480 [SAR 1:1 DAR 4:3], q=2-31, 200 kb/s, 90k tbn, 29.97 tbc
Stream mapping:
  Stream #0:0 -> #0:0 (mpeg4 -> png)
Press [q] to stop, [?] for help
[mpeg4 @ 0x2bbacc0] looks like this file was encoded with (divx4/(old)xvid/opendivx) -> forcing low_delay flag
frame=    1 fps=0.0 q=0.0 Lsize=N/A time=00:00:00.03 bitrate=N/A
video:474kB audio:0kB subtitle:0 global headers:0kB muxing overhead -100.004531%

out.png shows artefacts that can not be seen with 00000290.png:
$ mplayer tears.m4v -demuxer lavf -vc xvid -vo png