> account for a 150-sector offset

At a first glance this looks correct.
(It might be better to sanity check for overflow.)
If I had a VCD and if the CD drive in my laptop was
working, I'd test it:-)

> error field of struct scsireq is [...] unused

Right, only retsts should be checked.
I wouldn't bother to print sc.status, there is no useful
information afaics.

> submit those patches to mplayer development list

go ahead!

best regards
Matthias