alsa record example.c

最新推荐文章于 2024-06-07 20:30:00 发布
Yantai666
最新推荐文章于 2024-06-07 20:30:00 发布
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  /* 

 
 
 
 
  
    A Minimal Capture Program

 
 
 
 
  
  

 
 
 
 
  
    This program opens an audio interface for capture, configures it for

 
 
 
 
  
    stereo, 16 bit, 44.1kHz, interleaved conventional read/write

 
 
 
 
  
    access. Then its reads a chunk of random data from it, and exits. It

 
 
 
 
  
    isn't meant to be a real program.

 
 
 
 
  
  

 
 
 
 
  
    From on Paul David's tutorial : http://equalarea.com/paul/alsa-audio.html

 
 
 
 
  
  

 
 
 
 
  
    Fixes rate and buffer problems

 
 
 
 
  
  

 
 
 
 
  
    sudo apt-get install libasound2-dev

 
 
 
 
  
    gcc -o alsa-record-example -lasound alsa-record-example.c && ./alsa-record-example hw:0

 
 
 
 
  
  */

 
 
 
 
  
   

 
 
 
 
  
  #
  
  include 
  
  <stdio.h>

 
 
 
 
  
  #
  
  include 
  
  <stdlib.h>

 
 
 
 
  
  #
  
  include 
  
  <alsa/asoundlib.h>

 
 
 
 	      

 
 
 
 
  
  main (
  
  int argc, 
  
  char *argv[])

 
 
 
 
  
  {

 
 
 
   
  
  int i;

 
 
 
   
  
  int err;

 
 
 
   
  
  char *buffer;

 
 
 
   
  
  int buffer_frames = 
  
  128;

 
 
 
   
  
  unsigned 
  
  int rate = 
  
  44100;

 
 
 
   
  
  snd_pcm_t *capture_handle;

 
 
 
   
  
  snd_pcm_hw_params_t *hw_params;

 
 
 
 	
  
  snd_pcm_format_t format = SND_PCM_FORMAT_S16_LE;

 
 
 
 
  
   

 
 
 
   
  
  if ((err = 
  
  snd_pcm_open (&capture_handle, argv[
  
  1], SND_PCM_STREAM_CAPTURE, 
  
  0)) < 
  
  0) {

 
 
 
     
  
  fprintf (stderr, 
  
  "cannot open audio device %s (%s)\n", 

 
 
 
 
  
               argv[
  
  1],

 
 
 
              
  
  snd_strerror (err));

 
 
 
     
  
  exit (
  
  1);

 
 
 
 
  
    }

 
 
 
 
  
   

 
 
 
   
  
  fprintf(stdout, 
  
  "audio interface opened\n");

 
 
 
 		   

 
 
 
   
  
  if ((err = 
  
  snd_pcm_hw_params_malloc (&hw_params)) < 
  
  0) {

 
 
 
     
  
  fprintf (stderr, 
  
  "cannot allocate hardware parameter structure (%s)\n",

 
 
 
              
  
  snd_strerror (err));

 
 
 
     
  
  exit (
  
  1);

 
 
 
 
  
    }

 
 
 
 
  
   

 
 
 
   
  
  fprintf(stdout, 
  
  "hw_params allocated\n");

 
 
 
 				 

 
 
 
   
  
  if ((err = 
  
  snd_pcm_hw_params_any (capture_handle, hw_params)) < 
  
  0) {

 
 
 
     
  
  fprintf (stderr, 
  
  "cannot initialize hardware parameter structure (%s)\n",

 
 
 
              
  
  snd_strerror (err));

 
 
 
     
  
  exit (
  
  1);

 
 
 
 
  
    }

 
 
 
 
  
   

 
 
 
   
  
  fprintf(stdout, 
  
  "hw_params initialized\n");

 
 
 
 	

 
 
 
   
  
  if ((err = 
  
  snd_pcm_hw_params_set_access (capture_handle, hw_params, SND_PCM_ACCESS_RW_INTERLEAVED)) < 
  
  0) {

 
 
 
     
  
  fprintf (stderr, 
  
  "cannot set access type (%s)\n",

 
 
 
              
  
  snd_strerror (err));

 
 
 
     
  
  exit (
  
  1);

 
 
 
 
  
    }

 
 
 
 
  
   

 
 
 
   
  
  fprintf(stdout, 
  
  "hw_params access setted\n");

 
 
 
 	

 
 
 
   
  
  if ((err = 
  
  snd_pcm_hw_params_set_format (capture_handle, hw_params, format)) < 
  
  0) {

 
 
 
     
  
  fprintf (stderr, 
  
  "cannot set sample format (%s)\n",

 
 
 
              
  
  snd_strerror (err));

 
 
 
     
  
  exit (
  
  1);

 
 
 
 
  
    }

 
 
 
 
  
   

 
 
 
   
  
  fprintf(stdout, 
  
  "hw_params format setted\n");

 
 
 
 	

 
 
 
   
  
  if ((err = 
  
  snd_pcm_hw_params_set_rate_near (capture_handle, hw_params, &rate, 
  
  0)) < 
  
  0) {

 
 
 
     
  
  fprintf (stderr, 
  
  "cannot set sample rate (%s)\n",

 
 
 
              
  
  snd_strerror (err));

 
 
 
     
  
  exit (
  
  1);

 
 
 
 
  
    }

 
 
 
 	

 
 
 
   
  
  fprintf(stdout, 
  
  "hw_params rate setted\n");

 
 
 
 
  
   

 
 
 
   
  
  if ((err = 
  
  snd_pcm_hw_params_set_channels (capture_handle, hw_params, 
  
  2)) < 
  
  0) {

 
 
 
     
  
  fprintf (stderr, 
  
  "cannot set channel count (%s)\n",

 
 
 
              
  
  snd_strerror (err));

 
 
 
     
  
  exit (
  
  1);

 
 
 
 
  
    }

 
 
 
 
  
   

 
 
 
   
  
  fprintf(stdout, 
  
  "hw_params channels setted\n");

 
 
 
 	

 
 
 
   
  
  if ((err = 
  
  snd_pcm_hw_params (capture_handle, hw_params)) < 
  
  0) {

 
 
 
     
  
  fprintf (stderr, 
  
  "cannot set parameters (%s)\n",

 
 
 
              
  
  snd_strerror (err));

 
 
 
     
  
  exit (
  
  1);

 
 
 
 
  
    }

 
 
 
 
  
   

 
 
 
   
  
  fprintf(stdout, 
  
  "hw_params setted\n");

 
 
 
 	

 
 
 
   
  
  snd_pcm_hw_params_free (hw_params);

 
 
 
 
  
   

 
 
 
   
  
  fprintf(stdout, 
  
  "hw_params freed\n");

 
 
 
 	

 
 
 
   
  
  if ((err = 
  
  snd_pcm_prepare (capture_handle)) < 
  
  0) {

 
 
 
     
  
  fprintf (stderr, 
  
  "cannot prepare audio interface for use (%s)\n",

 
 
 
              
  
  snd_strerror (err));

 
 
 
     
  
  exit (
  
  1);

 
 
 
 
  
    }

 
 
 
 
  
   

 
 
 
   
  
  fprintf(stdout, 
  
  "audio interface prepared\n");

 
 
 
 
  
   

 
 
 
 
  
    buffer = 
  
  malloc(
  
  128 * 
  
  snd_pcm_format_width(format) / 
  
  8 * 
  
  2);

 
 
 
 
  
   

 
 
 
   
  
  fprintf(stdout, 
  
  "buffer allocated\n");

 
 
 
 
  
   

 
 
 
   
  
  for (i = 
  
  0; i < 
  
  10; ++i) {

 
 
 
     
  
  if ((err = 
  
  snd_pcm_readi (capture_handle, buffer, buffer_frames)) != buffer_frames) {

 
 
 
       
  
  fprintf (stderr, 
  
  "read from audio interface failed (%s)\n",

 
 
 
 
  
                 err, 
  
  snd_strerror (err));

 
 
 
       
  
  exit (
  
  1);

 
 
 
 
  
      }

 
 
 
     
  
  fprintf(stdout, 
  
  "read %d done\n", i);

 
 
 
 
  
    }

 
 
 
 
  
   

 
 
 
   
  
  free(buffer);

 
 
 
 
  
   

 
 
 
   
  
  fprintf(stdout, 
  
  "buffer freed\n");

 
 
 
 	

 
 
 
   
  
  snd_pcm_close (capture_handle);

 
 
 
   
  
  fprintf(stdout, 
  
  "audio interface closed\n");

 
 
 
 
  
   

 
 
 
   
  
  exit (
  
  0);

 
 
 
 
  
  }