[alsa-devel] Problem capturing from sound board

[André Prado]

Hello i am trying to do a simple program in order to capture the input
from the microphone in my OnBoard HDA Intel sound board.
However it doesnt work and gives me a segmentation fault. Any help is
appreciated.

#include <stdio.h>
#include <string.h>
#include <alsa/asoundlib.h>

int main(int argc, char** argv)
{
    register int err;
    int cardNum, totalCards;

    totalCards = 0;

    cardNum = -1;

    short buf[128];

    while(1)
    {
	snd_ctl_t *cardHandle;

    printf("\n***********\n");
   //Number of boards	

    if ((err = snd_card_next(&cardNum)) < 0)
        {
	    printf("%s\n", snd_strerror(err));
	    break;
	}

    if(cardNum<0)
    {
        break;
    }

    ++totalCards;

    char str[64];

    sprintf(str, "hw:%i", cardNum); (IS THIS THE RIGHT WAY TO NAME MY DEVICE?)


    snd_pcm_t *capture_handle;
    snd_pcm_hw_params_t *hw_params;



    if(err = snd_pcm_open( &capture_handle, str,
SND_PCM_STREAM_CAPTURE, 0 ) < 0 )
        {
	    printf("  %s\n", snd_strerror(err));
	    break;
	}

    snd_pcm_hw_params_malloc (&hw_params);
    snd_pcm_hw_params_any(capture_handle, hw_params);

    if(err = snd_pcm_hw_params_set_access(capture_handle, hw_params,
SND_PCM_ACCESS_RW_INTERLEAVED) < 0)
        printf("Nao e setar o acesso: %s\n", snd_strerror(err));

    unsigned int num_canais = 0;
    int ret;

    if(err = snd_pcm_hw_params_get_channels_max(hw_params, &num_canais) < 0)
        printf(" Nao e conseguir o numero de canais: %s\n", snd_strerror(err));

    printf("Numero de canais: %i\n",num_canais);

    // Configurando hardware

    // Resampling

    printf("Fim preparacao");
    unsigned int resample = 1;

    if (err = snd_pcm_hw_params_set_rate_resample(capture_handle,
hw_params, resample)<0)
        printf("Erro setando o sample: %s\n", snd_strerror(err));
    // Formato Little endian 16 bits
    snd_pcm_hw_params_set_format (capture_handle, hw_params,
SND_PCM_FORMAT_S16_LE);

    // Stereo
    if (err = snd_pcm_hw_params_set_channels (capture_handle, hw_params, 2) < 0)
	printf("Erro setando o numero de canais: %s\n", snd_strerror(err));

    // Playback Rate
    unsigned int actualRate = 44100;
    if (err = snd_pcm_hw_params_set_rate_near (capture_handle,
hw_params, &actualRate, 0) < 0)
	printf("Erro setando o rate de playback: %s\n", snd_strerror(err));

    // Setando os valores configurados no hardware.
    if (err = snd_pcm_hw_params (capture_handle, hw_params) < 0 )
	printf("Erro setando o hardware: %s\n", snd_strerror(err));

    // Tamanho do buffer recebido apos configurar o hardware
    snd_pcm_uframes_t bufferSize;
    snd_pcm_hw_params_get_buffer_size( hw_params, &bufferSize );
    //printf( "Init: Buffer size = %s", bufferSize);
    //_playbackFrames = bufferSize;

    printf( "\nBits significantes para amostra linear = %i\n",
snd_pcm_hw_params_get_sbits(hw_params));




    // Preparando para leitura
    int i=0;
    int d=0;

    if ((err = snd_pcm_prepare (capture_handle)) < 0)
  	printf("cannot prepare audio interface for use (%s)\n",snd_strerror(err));
		
			

    snd_pcm_hw_params_free (hw_params);

//    if ((err = snd_pcm_readi (capture_handle, buf, 128)) != 128)
  //   printf( "read from audio interface failed (%s)\n", snd_strerror (err));
    }
    snd_config_update_free_global();
    }


-- 
Att
André