sm-spc  streaming

S-DSP CLOCK : 24576000  [1024*24*1000]   (tolerance: 24592800 Hz to 24645600)
SPC CLOCK : 1024000 (MC/24)

SNES CLOCK : 21.477MHz (tolerance: ?)

6 rates selectable:
 2000, 4000, 6000, 8000, 10000, 12000

RATE	SAMPLES/FRAME	BLOCKS/FRAME
12KHZ	200		13
10KHZ	166.7		11
8KHZ	133.3		9
6KHZ	100		7
4KHZ	66.7		5
2KHZ	33.3		3

Prime buffer by sending 12x more blocks on initial transfer