When I use the mplayer "pause" key, it stops exactly where
I want it; bang-on. Then I record the number of seconds that
it has printed. Then I use something like

mencoder -ss 30.0 -endpos 10 -ovc copy -oac copy -o segment.dump stream.dump

When I play back the stream, it's not exactly what I wanted. In fact it seems
a good number of seconds (maybe 6) off.

How do you correct that?

Thanks in advance.

Reza.