mixer.c

this is sample code to control mixer in linux.

#include <stdio.h>
#include <fcntl.h>
#include <string.h>
#include <sys/soundcard.h>

#define ARM

int main(int argc, char *argv[])
{
    int volume_read, volume_write, mixerfd;
    /* check argument */
    if(argc != 3)
    {
        printf("usage: %s volume_write volume_read\n", argv[0]);
        printf("example: %s 30 50\n", argv[0]);
        exit(-1);
    }
    volume_write = atoi(argv[1]);
    volume_read = atoi(argv[2]);
    if(volume_write < 0 || volume_write > 100)
        volume_write = 30;
    if(volume_read < 0 || volume_read > 100)
        volume_read = 30;

    /* open mixer device */
#ifdef ARM
    mixerfd = open("/dev/sound/mixer", O_RDWR);
#else
    mixerfd = open("/dev/mixer", O_RDWR);
#endif
    if(mixerfd < 0)
    {
        perror("Mixer open error !!");
        exit(-1);
    }

    /* adjust volume */
    ioctl(mixerfd, SOUND_MIXER_WRITE_VOLUME, &volume_write);
    ioctl(mixerfd, SOUND_MIXER_READ_VOLUME, &volume_read);

    close(mixerfd);

    return 0;
}