[alsa-devel] Fwd: [Alsa-devel] Read the input of a soundcard with ALSA

[Nyx]

OK. I only want to read on the input of soundcard. So I wrote an other
program easier than the first, I write the data in file, but it seems that
it doesn't work...

#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include "alsa/asoundlib.h"
#include <errno.h>

unsigned int rate = 44100;
unsigned int nb_channels = 2;

int set_hwparams(snd_pcm_t *handle, snd_pcm_hw_params_t *hw_params)
{
    int err;
    int dir=0;
    if ((err = snd_pcm_hw_params_malloc (&hw_params)) < 0) {
        fprintf (stderr, "cannot allocate hardware parameter structure
(%s)\n", snd_strerror (err));
        exit (1);
    }

    if ((err = snd_pcm_hw_params_any (handle, hw_params)) < 0) {
        fprintf (stderr, "cannot initialize hardware parameter structure
(%s)\n", snd_strerror (err));
        exit (1);
    }
    printf("Initialisation des paramètres\n");

    if ((err = snd_pcm_hw_params_set_access (handle, hw_params,
SND_PCM_ACCESS_RW_INTERLEAVED)) < 0) {
        fprintf (stderr, "cannot set access type (%s)\n", snd_strerror
(err));
        exit (1);
    }
    printf("Access card configuration\n");

    if ((err = snd_pcm_hw_params_set_format (handle, hw_params,
SND_PCM_FORMAT_S16_LE)) < 0) {
        fprintf (stderr, "cannot set sample format (%s)\n", snd_strerror
(err));
        exit (1);
    }

    if ((err = snd_pcm_hw_params_set_rate_near (handle, hw_params, &rate,
&dir)) < 0) {
        fprintf (stderr, "cannot set sample rate (%s)\n", snd_strerror
(err));
        exit (1);
    }
    if ((err = snd_pcm_hw_params_set_channels (handle, hw_params, nb_chann))
< 0) {
        fprintf (stderr, "cannot set channel count (%s)\n", snd_strerror
(err));
        exit (1);
    }

    if ((err = snd_pcm_hw_params (handle, hw_params)) < 0) {
        fprintf (stderr, "cannot set parameters (%s)\n", snd_strerror
(err));
        exit (1);
    }
    printf("Parameters recorded\n");

    //snd_pcm_hw_params_free (hw_params);

    if ((err = snd_pcm_prepare (handle)) < 0) {
        fprintf (stderr, "cannot prepare audio interface for use (%s)\n",
snd_strerror (err));
        exit (1);
    }
        return 0;
}

int main(int   argc, char *argv[]){
    int err;
    int j;
    printf("Beginning \n");
    snd_pcm_hw_params_t *hw_params_capture, *hw_params_playback;
    short buf[256];
    FILE *file;

    fichier = fopen( "/root/Desktop/Test/Audio/Capture.001", "w");
    if (fichier == NULL) printf("cannot create file : %i\n", errno);
    else printf("file created\n");

    /*Open soundcard as capture*/
    snd_pcm_t *capture_handle;

    if ((err = snd_pcm_open (&capture_handle, "hw:0,0",
SND_PCM_STREAM_CAPTURE, 0)) < 0) {
        fprintf (stderr, "cannot open audio device %s (%s)\n",  argv[1],
 snd_strerror (err));
        exit (1);
    }

   set_hwparams(capture_handle, hw_params_capture);

   for (j = 0 ;  j < 256 ; j++) {
            if ((err = snd_pcm_readi (capture_handle, buf, 128)) < 0)
printf("cherche pas\n");
            putc(buf[j], file);       //write in file LEFT Channel
            putc(buf[j+1], file);  //write in file RIGHT Channel
            putc(0x0A, file);
    }

    printf("Close File\n");
    fclose(file);
    snd_pcm_close (capture_handle);
    return 0 ;
}


What do you think about this program... ? I searched about an How-to or some
help for capture on a soundcard with ALSA, but I didn't found

Thank you
-- 
K