OUTPUT_MUTE
l = ce4231_read(sc, SP_LEFT_OUTPUT_CONTROL) & ~OUTPUT_MUTE;
r = ce4231_read(sc, SP_RIGHT_OUTPUT_CONTROL) & ~OUTPUT_MUTE;
l |= OUTPUT_MUTE;
r |= OUTPUT_MUTE;
OUTPUT_MUTE) ? 1 : 0;
OUTPUT_ATTEN_BITS) | OUTPUT_MUTE;
OUTPUT_ATTEN_BITS) | OUTPUT_MUTE;
lm &= ~OUTPUT_MUTE;
rm &= ~OUTPUT_MUTE;