mplayer, Matrox G450 and interlaced output to TV via framebuffer

Hi, All!

I use mplayer to grab video from bttv card and play it on TV via patched 
matrox framebuffer (G450). If I deinterlace it with, e.g. -vop pp=lb, 
everything is ok. But when I try to play interlaced video, sometimes I get 
nice ppicture with smooth movements, but sometimes movements are rough. I 
think this is happend because there is no synchronization between data output 
to framebuffer memory and scanning this memory by TV-out hardware.
Is it possible to correct this behaviour?

-- 
Alexander Kogan
AutoWave Processes Group
Institute of Applied Physics RAS