mix_get
level = mix_get(m, SOUND_MIXER_PCM);
vol = mix_get(m, SOUND_MIXER_PCM);
pvol = mix_get(m, parent);
treble = mix_get(m, SOUND_MIXER_TREBLE);
bass = mix_get(m, SOUND_MIXER_BASS);
int mix_get(struct snd_mixer *m, u_int dev);