According to the Accuraterip database it has a read offset of +48, so it is (almost certainly) based on an NEC chip. That rules out many possibilities, so the most likely candidates are (in no particular order) a rebadged Pioneer or true Optiarc (IIRC, all the QSI ones are Mediatek), or an original Teac.
Can the drive scan? And does CD-DVD Speed give a choice of DVD scanning interval? (1ECC & 8ECC)
(You might need to check the registry to ensure the drive isn't blocked from scanning by CD-DVD Speed - see the Samsung FAQ for instructions.)