[MPlayer-users] decoding of MS-RLE in 4-bit is buggy

[Michael Günnewig]

Hallo.

The decoding of Microsoft-RLE in 4-bit doesn't work correctly under
all circumstances. As described at 

  http://www.pcisys.net/~melanson/codecs/msrle.txt

must the code be aligned at a word-boundary when in absolute mode. I
have an AVI file which decodes correctly under Windows. The
problematic segment is the following (in hex):

  00 09 77 70 78 88 80 00 3A 88 00 08 77 07 7F FF 29 FF 00 00

This code results that the variable rle_code will be 9 / 2, which will
be 4. This will decode the next 4 bytes into the corresponding 8
pixels. The 9th pixel will be interpreted by mplayer as an
encoded-code-segment instead of be a pixel with pal-index 9 (and skip
the 0 in the lsb) and an extra-byte for alignment. This results in
very strange decoded frames and warning-messages about violated
boundaries:

  MS RLE: stream ptr just went out of bounds (1)

The problematic AVI file (60 kB size) is available at:
  http://ls6-www.cs.uni-dortmund.de/~guennewi/mplayer-msrle-4bit.avi


  Michael