//--------------------------------------------------------------
original libpostproc_plugin always crashed (corrupt rsp in mmx code, libavcodec) - bithack used
original                      changed 
push rsp                -->   push rax
movd esp,mmxX           -->   mov eax,mmxX
cmp  rpl,[offset]       -->   nop; cmp al,[offset] 
pop rsp                 -->   pop rax
//--------------------------------------------------------------