Audio and Video synchronization with timestamps

I 开发者_如何学JAVAreceive audio packets from net (4 packets per second, 250ms each) and video - 15fps. Everything goes with my own timestamps. How should I sync them? I've seen the source code of one of our developers but he did syncing VIDEO according to audio. I.e. audio is always played immediately and video can be dropped or buffered. I don't think it is correct because audio can overrun video for a second or two - in that case we will not have actual video frames at all.

I'd like to know some basics in sync stuff. What should be buffered? Should audio and video in sync mode be played in separate thread(s)? Any clues would be regardful!

Thanks a lot!

I needed in smth like that - http://www.freepatentsonline.com/7680153.html

Pretty difficult to understand but I think this patent explains the basics of sync.