*

 * Program to illustrate /dev/dsp device

 * Records several seconds of sound, then echoes it back.

 * Runs until Control-C is pressed.

 */

#include <unistd.h>

#include <fcntl.h>

#include <sys/types.h>

#include <sys/ioctl.h>

#include <stdlib.h>

#include <stdio.h>

#include <linux/soundcard.h>

#define LENGTH 3                /* how many seconds of speech to store */

#define RATE 8000               /* the sampling rate */

#define SIZE 8                  /* sample size: 8 or 16 bits */

#define CHANNELS 1              /* 1 = mono 2 = stereo */

     /*

      * this buffer holds the digitized audio

      */

unsigned char buf[LENGTH * RATE * SIZE * CHANNELS / 8];

int main (int argc, char **argv)

{

    int fd;                     /* sound device file descriptor */

    int arg;                    /* argument for ioctl calls */

    int status;                 /* return status of system calls */

    /*

     * open sound device

     */

    if (argc != 2) {

        printf ("Usage: %s <DEVICE>\n", argv[0]);

        printf ("Example: %s /dev/dsp\n", argv[0]);

        printf ("Example: %s /dev/dsp1\n", argv[0]);

        return EXIT_SUCCESS;

    }

    fd = open (argv[1], O_RDWR);

    if (fd < 0) {

        perror ("open of sound device failed");

        return EXIT_FAILURE;

    }

    /*

     * set sampling parameters

     */

    arg = SIZE;                 /* sample size */

    status = ioctl (fd, SOUND_PCM_WRITE_BITS, &arg);

    if (status == -1)

        perror ("SOUND_PCM_WRITE_BITS ioctl failed");

    if (arg != SIZE)

        perror ("unable to set sample size");

    arg = CHANNELS;             /* mono or stereo */

    status = ioctl (fd, SOUND_PCM_WRITE_CHANNELS, &arg);

    if (status == -1)

        perror ("SOUND_PCM_WRITE_CHANNELS ioctl failed");

    if (arg != CHANNELS)

        perror ("unable to set number of channels");

    arg = RATE;                 /* sampling rate */

    status = ioctl (fd, SOUND_PCM_WRITE_RATE, &arg);

    if (status == -1)

        perror ("SOUND_PCM_WRITE_WRITE ioctl failed");

    while (1) {                 /* loop until Control-C */

        printf ("Say something:\n");

        status = read (fd, buf, sizeof (buf));  /* record some sound */

        if (status != sizeof (buf))

            perror ("read wrong number of bytes");

        printf ("You said:\n");

        status = write (fd, buf, sizeof (buf)); /* play it back */

        if (status != sizeof (buf))

            perror ("wrote wrong number of bytes");

        /*

         * wait for playback to complete before recording again

         */

        status = ioctl (fd, SOUND_PCM_SYNC, 0);

        if (status == -1)

            perror ("SOUND_PCM_SYNC ioctl failed");

    }

    return EXIT_SUCCESS;

}