snd_adjust.c

来自「基于linux的录音程序」· C语言 代码 · 共 58 行

#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <linux/soundcard.h>
#include <sys/ioctl.h>
#include <errno.h>
#include "snd_adjust.h"

int snd_adjust()
{
	int fd_m;
	int val,left,right;
	int err;

	fd_m = open("/dev/mixer",O_RDONLY);
	if(fd_m<0)
	{
		perror("open mixer failed~~\n");
                return 0;//leo
		//exit(0); //leo
	}
	ioctl(fd_m,MIXER_READ(SOUND_MIXER_SPEAKER),&val);
	printf("SPEAKER gain is %d %%\n",val);
	close(fd_m);

	fd_m = open("/dev/mixer",O_RDONLY);
	if(fd_m<0)
	{
		perror("open mixer failed~~  read ~~\n");
                return 0;
		//exit(1);//leo
	}

	val = 0;
	left = 100;
	right = 100;
	val = left | right<<8;
	err = ioctl(fd_m,SOUND_MIXER_WRITE_SPEAKER,&val);
	if( err<0 )
	{
		perror("SOUND MIXER WRITE SPEAKER failed\n");
		//exit(1);
	}

	val = 0;
	left = 255;
	right = 255;
	val = left| right<<8;
	ioctl(fd_m,SOUND_MIXER_WRITE_MIC,&val);
	 if(err=-1)
        {
                perror("MIXER_WRITE_MIC failed\n");
                //exit(1);
        }
	close(fd_m);
	return 1;
}