when i was playing with mplayer in my ras pi. I found that it always appear warning "Your system is too slow to play this". And voice often play faster than the video.
after some modifying with config and option, i found nothing was helpful.
(Btw, you should tune the speed of lcd screen at least 48000000, but you may find some strange colour behaviour appear lol)
So, finally, i tried to re encode my video.
result turns out that we can simply solve this problem by encode the video into the older encoding format like mpg or ogg.
don't use format like mp4 or flv
mplayer -nolirc -vo fbdev2:/dev/fb1 -fs -zoom -x 480 -y 320 ~/Videos/BadApple.mpg
Look at the a-v, You can see a significant difference between the mpg and flv.
Which means flv always face sync problem while mpg not.
-lavdopts skipframe=nonref:skiploopfilter=all may helo