BeagleBoard XM MCBSP Driver

This might not be the best place to post this question, but I am trying to write a simple driver for MCBSP1 to read and write 16 bit mono audio, sampled at 8KHz, and there are a few things I don’t understand. 1) what is the difference between the interface clock, CLKS, the functional clock, and the bit clocks (CLKR and CLKX)?? And 2) I don’t completely understand the data transfer process, I thought I did, but some of the wording in DM3730 manual didn’t make sense to me. It says that up to 128 frames (or 32-bit words…??) can be transferred in one frame sync, (the frame sync is the sample rate clock right…??). In my situation I only need to transfer one frame, or really 16 bits, every 8 KHz. Why would anyone ever want to send 128 frames per transition of the sample rate clock?? If I had 9 channel stereo with a sub, I would still only want to transfer 10 frames per sample rate…?! I think I am misunderstanding something. Please help.

Thank you,