I joined the mplayer mailing list and have tried to seek help/information from those nice folks.. The following is part of one of my exchanges. Maybe the part about the timestamp may be of some help?
I asked a couple specific questions and included some quotes from other posts to provide an idea of what we're looking at as the cause. I can't tell you what the exact problem is because we're still trying to figure
that
out... And a good place to start is by comparing the differences between the software that has the problem and software that doesn't. We're trying to figure out what mplayer does, if anything, with regards to repacking, the pes layer, pcr data, etc. during the "playback" of a VDR
"recording".
nothing particular: the pes packetization is as standard as you can get, except that IIRC there's a timestamp on every single frame, rather than once every 0.5-0.7 seconds; this fact alone can make a lot of difference during playback. Does the desync that you are experiencing get worse with time or does it regularly decrease and next increase?