That makes sense, I never knew that. Thanks!

Now I wonder where the Audio CD 44.1k sample rate came from. 44,100 divided by 75 is 588 samples per channel. That doesn't seem like a particularly useful number, whereas 48k / 75 is a more appealing 640.

Right - is it not the case that this object is tracking Mode 1 CD-ROM physical (i.e. rotational) frames, not audio/video frames? That is .. a Mode 1× CD-ROM drive reads 150/2 = 75 consecutive sectors per second ... 150k/sec transfer rate ..