[LAD] reading and writing to /dev/dsp

Hi,

I am running a .mp3 file using 'xine' without any issues on my Fedora
Core 8 machine.

I am reading /dev/dsp and storing it in some file.
i.e. cat /dev/dsp > musicfile

Now I am stopping 'xine' and then writing 'musicfile' to /dev/dsp.
i.e. cat musicfile > /dev/dsp

In this case I can hear the music but with a lot of noise in it.
Is there any way I can remove/reduce this noise from 'musicfile'?

I also tried following program (it records the voice and plays it
immediately) that I got from net to understand how to write to /dev/dsp
but it does not seem to record my voice and hence plays nothing and
there is noise only.

-------------------------------------------------------
#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 fd; /* sound device file descriptor */
    int arg; /* argument for ioctl calls */
    int status; /* return status of system calls */

    /* open sound device */
    fd = open("/dev/dsp", O_RDWR);
    if (fd < 0) {
        perror("open of /dev/dsp failed");
        exit(1);
    }

    /* 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");
    }
}
---------------------------------------------------------------------------------------
Regards,
Girish

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Received on Thu Jul 23 16:15:01 2009