Alsa snd_hctl_find_elem function test

alsa-test-hctl-find-elem.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <termios.h>
#include <sys/ioctl.h>
#include <sys/signal.h>
#include <sys/types.h>
#include <time.h>

// gcc -g -o test2-api test2api.c `pkg-config --cflags --libs alsa`

#include <alsa/asoundlib.h>

main() {

    int err;

	snd_hctl_t *handle;
	snd_hctl_elem_t *elem;

	snd_ctl_elem_info_t *info;
	snd_ctl_elem_id_t *id;
	snd_ctl_elem_value_t *control;
	snd_ctl_elem_info_alloca(&info);


    char *card = "hw:1";
    int  numid = 26;


	if ((err = snd_hctl_open(&handle, card, 0)) < 0) {
		error("Control %s open error: %s", card, snd_strerror(err));
		goto errorExit;
	}
	if ((err = snd_hctl_load(handle)) < 0) {
		error("Control %s local error: %s\n", card, snd_strerror(err));
		goto errorExit;
	}

	snd_ctl_elem_id_alloca(&id);
    snd_ctl_elem_id_set_interface(id, SND_CTL_ELEM_IFACE_MIXER);
    //snd_ctl_elem_id_set_numid (id, 3);
    snd_ctl_elem_id_set_name(id, "Line Playback Volume");


    // verify that element has a defined type
    elem = snd_hctl_find_elem (handle, id);
    if (elem == NULL) {
       fprintf(stderr, "Control %s numid=%d fail to find control\n", card, numid);
       goto errorExit;
    }

	snd_ctl_elem_value_alloca(&control);
    snd_ctl_elem_value_set_id(control, id);


    snd_ctl_elem_info_alloca(&info);
	if ((err = snd_hctl_elem_info (elem, info)) < 0) {
        fprintf(stderr, "Control %s numid=%d fail to request info \n", card, numid);
		goto errorExit;
	}



	fprintf (stderr,"fin\n");

errorExit:
	fprintf (stderr,"Error\n");