orginal patch  by (Marc Hoffman <mmh at pleasantst dot com>)
critical fixes by (Reza Jelveh <reza.jelveh at tu-harburg dot de>)

known bugs/issues, which should be fixed ASAP by someone who has a ppc:
0..255 vs. 16..235
unneeded recalculation of tables
general cleaup, like removing double initalizing of variables


git-svn-id: file:///var/local/repositories/mplayer/trunk/postproc@12699 b3059339-0415-0410-9bf9-f77b7e298cf2