While long live encoding from sky4linux device like that:

ffmpeg -i /dev/dvb/stream\
  -sameq -vcodec mpeg2video\
  -acodec copy  -f mpeg2video /dev/null

I see a memory leak with top and vmstat
file memory_leak.mpg - part of that stream 
(cat /dev/dvb/stream >memory_leak_mpg) ), that shows leakage
Sorry for size, but it can't be smaller - bug depelo itself only in a long
while.

Probably there are errors in stream, that are not fully traced in mpeg2video
module