Linux ALSA/Sound-API Questions - How do you mute?

• How do I mute sound using C? Is there an ALSA function call?

• Are there any other function calls/APIs that can MUTE the microphone?

• I have written some co开发者_StackOverflow社区de to do audio playback using ALSA, and I have noticed a DELAY before the sound starts playing ... how do I reduce DELAY or LATENCY on sound playback?

x

#include <alsa/asoundlib.h>

void SetAlsaMasterMute()
{
    long min, max;
    snd_mixer_t *handle;
    snd_mixer_selem_id_t *sid;
    const char *card = "default";
    const char *selem_name = "Master";

    snd_mixer_open(&handle, 0);
    snd_mixer_attach(handle, card);
    snd_mixer_selem_register(handle, NULL, NULL);
    snd_mixer_load(handle);

    snd_mixer_selem_id_alloca(&sid);
    snd_mixer_selem_id_set_index(sid, 0);
    snd_mixer_selem_id_set_name(sid, selem_name);
    snd_mixer_elem_t* elem = snd_mixer_find_selem(handle, sid);

    if (snd_mixer_selem_has_playback_switch(elem)) {
        snd_mixer_selem_set_playback_switch_all(elem, 0);
    }

    snd_mixer_close(handle);
}

references: here and official api here.