http://ffmpeg.sourceforge.net

 Here's a shared library of libavcodec. It has been compiled with 
Gcc 2.95.2 with -m68020 and works only under MiNT 1.15.3 or more and
MagiC 6. TOS cannot load .SLB, but an SLB loader exist with MetaDOS:
ftp://ftp.uni-muenster.de/pub/atari/Utilities/slbld028.lzh 
http://www.muenster.de/~reschke/soft_e.html

 Requirements:
  - 68020 or higher
  - MiNT 1.15.3 or MagiC 6 or MetaDOS 2.74.
