Meanwhile, I've played back a vdr recording in xine (xine-ui) (the file itself, not through vdr) and can confirm the a/v sync problem is still there.
I played back the same recording with mplayer and the a/v sync problem seems to be gone---maybe with the small note that mplayer takes a few moments to adjust. This pretty much rules out vdr and vdr-xine as the source of the problem as well.
As far as I know, mplayer and ffmpeg use the same codebase (mostly).
From the above, I deduce that xine-lib or my configuration thereof produces the
a/v sync problem.
Can anyone confirm or contradict my thesis?
If it is in fact xine-lib that is the problem, does anyone know how to approach the problem?