feeder_find
f = feeder_find(c, FEEDER_EQ);
struct pcm_feeder *feeder_find(struct pcm_channel *c, u_int32_t type);
f = feeder_find(c, FEEDER_EQ);
f = feeder_find(c, FEEDER_EQ);
f = feeder_find(c, FEEDER_RATE);
f = feeder_find(c, FEEDER_EQ);