music is broken after adjusting dpll clock ..?

Hi

I use madplay on omap5912 to play mp3 music. The mp3 music can be play
smoothly. But if I adjust dpll clock, the music become rugged. Is there any addition setting of clock rate ? My code to adjust is :

//to adjust as 192 MHz
*dpll &= ~(0x7f) << 5;
*dpll |= (0x40 << 5);

//to adjust as 96 MHz
*dpll &= ~(0x7f) << 5;
*dpll |= (0x41 << 5);

In fact, I want to develop a dynamic clock scaling system, but the music become rugged when I change dpll clock.

How to adjust clock correctly and not to affect music ?

regards

D.G.Lin