AMIXER_PCM_F_C
amix_d = mixer->amixers[AMIXER_PCM_F_C*CHN_NUM];
amix_d = mixer->amixers[AMIXER_PCM_F_C*CHN_NUM+1];
case MIXER_PCM_C_S: return AMIXER_PCM_F_C;
case AMIXER_PCM_F: return AMIXER_PCM_F_C;