使用alsa库函数调节音量和开关声音

使用alsa库函数调节音量，代码如下：

#include <stdio.h>
#include <stdlib.h>
#include <alsa/asoundlib.h>
#define card        "default"
#define selem_name  "PCM"
int main(int argc,char**argv) {
    snd_mixer_t *handle;
    snd_mixer_selem_id_t *sid;
    // const char *card = "hw:2";
    // const char *selem_name = "Line Out";
    long volume = atoi(argv[1]); // Assuming range is 0-63 and 50% is around 31. Adjust as needed.

    int err = snd_mixer_open(&handle, 0);
    if (err < 0) {
        fprintf(stderr, "Error opening mixer: %s\n", snd_strerror(err));
        return -1;
    }

    err = snd_mixer_attach(handle, card);
    if (err < 0) {
        fprintf(stderr, "Error attaching mixer to card: %s\n", snd_strerror(err));
        snd_mixer_close(handle);
        return -1;
    }

    err = snd_mixer_selem_register(handle, NULL, NULL);
    if (err < 0) {
        fprintf(stderr, "Error registering mixer elements: %s\n", snd_strerror(err));
        snd_mixer_close(handle);
        return -1;
    }

    err = snd_mixer_load(handle);
    if (err < 0) {
        fprintf(stderr, "Error loading mixer: %s\n", snd_strerror(err));
        snd_mixer_close(handle);
        return -1;
    }

    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 (elem == NULL) {
        fprintf(stderr, "Could not find element: %s\n", selem_name);
        snd_mixer_close(handle);
        return -1;
    }

    err = snd_mixer_selem_set_playback_volume_all(elem, volume);
    if (err < 0) {
        fprintf(stderr, "Error setting volume: %s\n", snd_strerror(err));
        snd_mixer_close(handle);
        return -1;
    }
      err = snd_mixer_selem_set_playback_switch_all(elem,atoi(argv[1]));
      if (err < 0) {
        fprintf(stderr, "Error setting volume: %s\n", snd_strerror(err));
        snd_mixer_close(handle);
        return -1;
    }

    snd_mixer_close(handle);

    return 0;
}