[alsa-devel] Playback open error: Device or resource busy

Guilherme grlongo.ireland at gmail.com
Mon Jun 15 23:46:18 CEST 2009


Mates...

I am running a simple app that I found called pcm.c and I can't get 
through with that.  It creates  and send  a simple sine wave to the 
speakers!

When I run the app I get the following error:

guilherme at lap:/home/guilherme/Experimentos# ./PCM
Playback device is plughw:0,0
Stream parameters are 44100Hz, S16_LE, 1 channels
sine wave rate is 0 0.0000Hz
Using transfer method: write
Playback open error: Device or resource busy

Every application I start playbacks the sound without a problem. Is 
there any special conf I should do to free the Device?

Here is the code:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sched.h>
#include <errno.h>
#include <getopt.h>
#include <alsa/asoundlib.h>
#include <sys/time.h>
#include <math.h>

static char *device = "plughw:0,0";                    //playback device 
aplay -l
static snd_pcm_format_t format = SND_PCM_FORMAT_S16;   //sample format 
unsigned 16 bit endian
static unsigned int rate = 44100;                      //stream rate
static unsigned int channels = 1;                       //contagem dos 
canais
static unsigned int buffer_time = 500000;              //ring buffer 
length on us
static unsigned int period_time = 100000;              //period time in us
static double freq = 400;                              // frequencia da 
senóide em Hz
static int verbose = 0;                                //verbose flag
static int resample = 1;                               //abilitar 
alsa-lib resampling
static int period_event = 0;                           // produz um 
event pool a cada periodo

static snd_pcm_sframes_t buffer_size;                  //quantidade de 
buffers frames
static snd_pcm_sframes_t period_size;                  //quantidade de 
periods frames
static snd_output_t *output = NULL;                    //ALSA usa esse 
ponteiro para lidar com output objects


static void generate_sine(const snd_pcm_channel_area_t *areas,
                                         snd_pcm_uframes_t offset,
                                         int count, double *_phase)
{
       static double max_phase = 2. * M_PI;
       double phase = *_phase;
       double step = max_phase*freq / (double)rate;
       double res;
       unsigned char *samples[channels], *tmp;
       int steps[channels];
       unsigned int chn, byte;
             union {
               int i;
               unsigned char c[4];
       } ires;
       unsigned int maxval = (1 << (snd_pcm_format_width(format) - 1)) - 1;
       int bps = snd_pcm_format_width(format) / 8; //bits per sample
             /*verificar e preparar o conteúdo das areas*/
       for (chn = 0; chn < channels; chn++) {
           if ((areas[chn].first % 8) != 0) {
                   printf("areas[%i].first == %i, abortando...\n", chn, 
areas[chn].first);
                   exit(EXIT_FAILURE);
           }
           //pega endereço e offset da area
           samples[chn] = /*(signed short *)*/(((unsigned char 
*)areas[chn].addr) + (areas[chn].first / 8));
                  if ((areas[chn].step % 16) != 0) {
               printf("areas[%i].step == %i, aborting...\n", chn, 
areas[chn].step);
               exit(EXIT_FAILURE);
        }
                         steps[chn] = areas[chn].step / 8;
               samples[chn] += offset * steps[chn];
       }
             //completa os channels da area
       while(count-- > 0) {
           res = sin(phase) * maxval;
           ires.i = res;
           tmp = ires.c;
           for (chn = 0; chn < channels; chn++) {
                   for (byte = 0; byte < (unsigned int)bps; byte++) 
*(samples[chn] + byte) = tmp[byte];
                       samples[chn] += steps[chn];
                   }
                   phase += step;
                   if (phase >= max_phase)
                           phase -= max_phase;
                   }
                   *_phase = phase;
 
}                              

static int set_hwparams(snd_pcm_t *handle,
                               snd_pcm_hw_params_t *params,
                               snd_pcm_access_t access)
{
       unsigned int rrate;
       snd_pcm_uframes_t size;
       int err, dir;
             /*escolha todos os parametros*/
       err = snd_pcm_hw_params_any(handle, params);
       if (err < 0) {
               printf("Broken configuration for playback: no 
configuration available: %s\n", snd_strerror(err));
               return err;
       }
             /*set hardware resampling*/
       err = snd_pcm_hw_params_set_rate_resample(handle, params, resample);
       if (err < 0) {
               printf("Resampling setup failed for playback: %s\n", 
snd_strerror(err));
               return err;
       }
           /* set the interleaved read/write format */
     err = snd_pcm_hw_params_set_access(handle, params, access);
     if (err < 0) {
           printf("Access type not available for playback: %s\n", 
snd_strerror(err));
           return err;
      }
          /* set the sample format SND_PCM_FORMAT_S16 */
      err = snd_pcm_hw_params_set_format(handle, params, format);
      if (err < 0) {
            printf("Sample format not available for playback: %s\n", 
snd_strerror(err));
            return err;
     }
           /* set the count of channels 1  */
      err = snd_pcm_hw_params_set_channels(handle, params, channels);
      if (err < 0) {
            printf("Channels count (%i) not available for playbacks: 
%s\n", channels, snd_strerror(err));
            return err;
     }
         /* set the stream rate */
      rrate = rate;
      err = snd_pcm_hw_params_set_rate_near(handle, params, &rrate, 0);
      if (err < 0) {
            printf("Rate %iHz not available for playback: %s\n", rate, 
snd_strerror(err));
            return err;
     }
     if (rrate != rate) {
            printf("Rate doesn't match (requested %iHz, get %iHz)\n", 
rate, err);
           return -EINVAL;
     }
     /* set the buffer time */
     err = snd_pcm_hw_params_set_buffer_time_near(handle, params, 
&buffer_time, &dir);
     if (err < 0) {
          printf("Unable to set buffer time %i for playback: %s\n", 
buffer_time, snd_strerror(err));
          return err;
     }
     err = snd_pcm_hw_params_get_buffer_size(params, &size);
     if (err < 0) {
          printf("Unable to get buffer size for playback: %s\n", 
snd_strerror(err));
          return err;
     }
     buffer_size = size;
     /* set the period time */
     err = snd_pcm_hw_params_set_period_time_near(handle, params, 
&period_time, &dir);
     if (err < 0) {
          printf("Unable to set period time %i for playback: %s\n", 
period_time, snd_strerror(err));
          return err;
     }
     err = snd_pcm_hw_params_get_period_size(params, &size, &dir);
     if (err < 0) {
          printf("Unable to get period size for playback: %s\n", 
snd_strerror(err));
          return err;
     }
     period_size = size;
     /* write the parameters to device */
     err = snd_pcm_hw_params(handle, params);
     if (err < 0) {
          printf("Unable to set hw params for playback: %s\n", 
snd_strerror(err));
          return err;
     }
     return 0;
}



static int set_swparams(snd_pcm_t *handle, snd_pcm_sw_params_t *swparams) {

           int err;
                     /*pegar os parametros atuais swparams*/
           err = snd_pcm_sw_params_current(handle, swparams);
           if (err < 0) {
               printf("Unable to determine current swparams for 
playback: %s\n", snd_strerror(err));
               return err;
           }
           /*Começa a transferência quando o buffer está quase cheio*/
           /*(buffer_size / avail_min) * avail_min */
           err = snd_pcm_sw_params_set_avail_min(handle, swparams, 
(buffer_size / period_size) * period_size);
           if (err < 0) {
               printf("Unable to set start threshold mode for playback: 
%s\n", snd_strerror(err));
               return err;
           }
           /* allow the transfer when at least period_size samples can 
be processed */
         /* or disable this mechanism when period event is enabled (aka 
interrupt like style processing) */
         err = snd_pcm_sw_params_set_avail_min(handle, swparams, 
period_event ? buffer_size : period_size);
         if (err < 0) {
                printf("Unable to set avail min for playback: %s\n", 
snd_strerror(err));
                 return err;
        }
         /* enable period events when requested */
        if (period_event) {
                 err = snd_pcm_sw_params_set_period_event(handle, 
swparams, 1);
                 if (err < 0) {
                         printf("Unable to set period event: %s\n", 
snd_strerror(err));
                         return err;
                }
         }
         /* write the parameters to the playback device */
         err = snd_pcm_sw_params(handle, swparams);
         if (err < 0) {
                 printf("Unable to set sw params for playback: %s\n", 
snd_strerror(err));
                 return err;
         }
         return 0;
}

/* Tenta recuperar estados de underrun e suspend */

static int xrun_recovery(snd_pcm_t *handle, int err)
{
           if (verbose)
                   printf("stream recovery\n");
           if (err == -EPIPE) {      //under-run*/
                   err = snd_pcm_prepare(handle);
                   if (err < 0)
                               printf("Can't recovery from underrun, 
prepare failed: %s\n", snd_strerror(err));
                   return 0;
           } else if (err == -ESTRPIPE) {
                   while ((err = snd_pcm_resume(handle)) == -EAGAIN)
                           sleep(1); /*espera pela release flag*/
                   if (err < 0) {
                           err = snd_pcm_prepare(handle);
                           if (err < 0)
                                   printf("Can't recovery from suspend, 
prepare failed: %s\n", snd_strerror(err));
                           }
                           return 0;
                   }
                   return err;
}

/* Metodo de transferência *WRITE-ONLY* */
static int write_loop(snd_pcm_t *handle,
                            signed short *samples,
                            snd_pcm_channel_area_t *areas)
{
       double phase = 0;
       signed short *ptr;
       int err, cptr;
             while(1) {
           generate_sine(areas, 0, period_size, &phase);
           ptr = samples;
           cptr = period_size;
           while (cptr > 0) {
                   err = snd_pcm_writei(handle, ptr, cptr);
                   if (err == -EAGAIN)
                                continue;
                   if (err < 0) {
                        if (xrun_recovery(handle, err) < 0) {
                                printf("Write error: %s\n", 
snd_strerror(err));
                                exit(EXIT_FAILURE);
                        }//if
                        ptr += err * channels;
                        cptr -= err;
                  }//if
                   }//if

        }//while
}


/*
*   Método de transferência - write and wait por espaço no buffer
*/

static int wait_for_poll(snd_pcm_t *handle, struct pollfd *ufds, 
unsigned int count)
{
       unsigned short revents;

       while (1) {
                poll(ufds, count, -1);
                snd_pcm_poll_descriptors_revents(handle, ufds, count, 
&revents);
                if (revents & POLLERR)
                       return -EIO;
                if (revents & POLLOUT)
                       return 0;
       }
}


static int write_and_poll_loop(snd_pcm_t *handle,
                                signed short *samples,
                                snd_pcm_channel_area_t *areas)
 {
         struct pollfd *ufds;
         double phase = 0;
         signed short *ptr;
         int err, count, cptr, init;

         count = snd_pcm_poll_descriptors_count (handle);
         if (count <= 0) {
                 printf("Invalid poll descriptors count\n");
                 return count;
         }

         ufds = malloc(sizeof(struct pollfd) * count);
         if (ufds == NULL) {
                 printf("No enough memory\n");
                 return -ENOMEM;
         }
         if ((err = snd_pcm_poll_descriptors(handle, ufds, count)) < 0) {
                 printf("Unable to obtain poll descriptors for playback: 
%s\n", snd_strerror(err));
                 return err;
         }

         init = 1;
         while (1) {
                 if (!init) {
                         err = wait_for_poll(handle, ufds, count);
                         if (err < 0) {
                                if (snd_pcm_state(handle) == 
SND_PCM_STATE_XRUN ||
                                     snd_pcm_state(handle) == 
SND_PCM_STATE_SUSPENDED) {
                                         err = snd_pcm_state(handle) == 
SND_PCM_STATE_XRUN ? -EPIPE : -ESTRPIPE;
                                         if (xrun_recovery(handle, err) 
< 0) {
                                                 printf("Write error: 
%s\n", snd_strerror(err));
                                                 exit(EXIT_FAILURE);
                                         }
                                         init = 1;
                                 } else {
                                         printf("Wait for poll failed\n");
                                        return err;
                                 }
                         }
                 }

                 generate_sine(areas, 0, period_size, &phase);
                 ptr = samples;
                cptr = period_size;
                 while (cptr > 0) {
                         err = snd_pcm_writei(handle, ptr, cptr);
                         if (err < 0) {
                                 if (xrun_recovery(handle, err) < 0) {
                                         printf("Write error: %s\n", 
snd_strerror(err));
                                         exit(EXIT_FAILURE);
                                 }
                                 init = 1;
                                break;  /* skip one period */
                         }
                         if (snd_pcm_state(handle) == 
SND_PCM_STATE_RUNNING)
                                 init = 0;
                         ptr += err * channels;
                         cptr -= err;
                        if (cptr == 0)
                                 break;
                          /* it is possible, that the initial buffer 
cannot store */
                         /* all data from the last period, so wait 
awhile */
                         err = wait_for_poll(handle, ufds, count);
                         if (err < 0) {
                                 if (snd_pcm_state(handle) == 
SND_PCM_STATE_XRUN ||
                                    snd_pcm_state(handle) == 
SND_PCM_STATE_SUSPENDED) {
                                         err = snd_pcm_state(handle) == 
SND_PCM_STATE_XRUN ? -EPIPE : -ESTRPIPE;
                                         if (xrun_recovery(handle, err) 
< 0) {
                                                 printf("Write error: 
%s\n", snd_strerror(err));
                                                 exit(EXIT_FAILURE);
                                         }
                                         init = 1;
                                 } else {
                                         printf("Wait for poll failed\n");
                                        return err;
                                 }
                         }
                }
         }
}



/*
*  Metodo de transferencia - Notificação assincrona
*/


struct async_private_data {
        signed short *samples;
        snd_pcm_channel_area_t *areas;
        double phase;
};


static void async_callback(snd_async_handler_t *ahandler)
{
        snd_pcm_t *handle = snd_async_handler_get_pcm(ahandler);
        struct async_private_data *data = 
snd_async_handler_get_callback_private(ahandler);
         signed short *samples = data->samples;
         snd_pcm_channel_area_t *areas = data->areas;
        snd_pcm_sframes_t avail;
         int err;
                avail = snd_pcm_avail_update(handle);
         while (avail >= period_size) {
                generate_sine(areas, 0, period_size, &data->phase);
                 err = snd_pcm_writei(handle, samples, period_size);
                 if (err < 0) {
                         printf("Write error: %s\n", snd_strerror(err));
                        exit(EXIT_FAILURE);
                }
                 if (err != period_size) {
                         printf("Write error: written %i expected 
%li\n", err, period_size);
                        exit(EXIT_FAILURE);
                }
                 avail = snd_pcm_avail_update(handle);
         }
}


static int async_loop(snd_pcm_t *handle,
                       signed short *samples,
                      snd_pcm_channel_area_t *areas)
 {
         struct async_private_data data;
        snd_async_handler_t *ahandler;
         int err, count;

        data.samples = samples;
         data.areas = areas;
        data.phase = 0;
         err = snd_async_add_pcm_handler(&ahandler, handle, 
async_callback, &data);
         if (err < 0) {
                 printf("Unable to register async handler\n");
                 exit(EXIT_FAILURE);
        }
        for (count = 0; count < 2; count++) {
                generate_sine(areas, 0, period_size, &data.phase);
                 err = snd_pcm_writei(handle, samples, period_size);
                 if (err < 0) {
                        printf("Initial write error: %s\n", 
snd_strerror(err));
                        exit(EXIT_FAILURE);
                 }
                 if (err != period_size) {
                         printf("Initial write error: written %i 
expected %li\n", err, period_size);
                        exit(EXIT_FAILURE);
                 }
         }
         if (snd_pcm_state(handle) == SND_PCM_STATE_PREPARED) {
                 err = snd_pcm_start(handle);
                 if (err < 0) {
                        printf("Start error: %s\n", snd_strerror(err));
                         exit(EXIT_FAILURE);
                 }
         }

        /* because all other work is done in the signal handler,
            suspend the process */
         while (1) {
                 sleep(1);
         }
}

/*
*   Transfer method - asynchronous notification + direct write
*/

 static void async_direct_callback(snd_async_handler_t *ahandler)
 {
         snd_pcm_t *handle = snd_async_handler_get_pcm(ahandler);
         struct async_private_data *data = 
snd_async_handler_get_callback_private(ahandler);
         const snd_pcm_channel_area_t *my_areas;
         snd_pcm_uframes_t offset, frames, size;
         snd_pcm_sframes_t avail, commitres;
         snd_pcm_state_t state;
         int first = 0, err;
                 while (1) {
                 state = snd_pcm_state(handle);
                 if (state == SND_PCM_STATE_XRUN) {
                         err = xrun_recovery(handle, -EPIPE);
                         if (err < 0) {
                                 printf("XRUN recovery failed: %s\n", 
snd_strerror(err));
                                 exit(EXIT_FAILURE);
                         }
                         first = 1;
                 } else if (state == SND_PCM_STATE_SUSPENDED) {
                         err = xrun_recovery(handle, -ESTRPIPE);
                         if (err < 0) {
                                 printf("SUSPEND recovery failed: %s\n", 
snd_strerror(err));
                                 exit(EXIT_FAILURE);
                         }
                 }
                 avail = snd_pcm_avail_update(handle);
                 if (avail < 0) {
                         err = xrun_recovery(handle, avail);
                         if (err < 0) {
                                 printf("avail update failed: %s\n", 
snd_strerror(err));
                                  exit(EXIT_FAILURE);
                         }
                         first = 1;
                         continue;
                 }
                 if (avail < period_size) {
                         if (first) {
                                 first = 0;
                                 err = snd_pcm_start(handle);
                                 if (err < 0) {
                                         printf("Start error: %s\n", 
snd_strerror(err));
                                         exit(EXIT_FAILURE);
                                }
                        } else {
                                 break;
                         }
                         continue;
                 }
                size = period_size;
                 while (size > 0) {
                         frames = size;
                         err = snd_pcm_mmap_begin(handle, &my_areas, 
&offset, &frames);
                         if (err < 0) {
                                 if ((err = xrun_recovery(handle, err)) 
< 0) {
                                         printf("MMAP begin avail error: 
%s\n", snd_strerror(err));
                                         exit(EXIT_FAILURE);
                                 }
                                 first = 1;
                         }
                         generate_sine(my_areas, offset, frames, 
&data->phase);
                         commitres = snd_pcm_mmap_commit(handle, offset, 
frames);
                         if (commitres < 0 || 
(snd_pcm_uframes_t)commitres != frames) {
                                 if ((err = xrun_recovery(handle, 
commitres >= 0 ? -EPIPE : commitres)) < 0) {
                                         printf("MMAP commit error: 
%s\n", snd_strerror(err));
                                         exit(EXIT_FAILURE);
                                 }
                                 first = 1;
                         }
                         size -= frames;
                 }
        }
}


static int async_direct_loop(snd_pcm_t *handle,
                              signed short *samples ATTRIBUTE_UNUSED,
                              snd_pcm_channel_area_t *areas 
ATTRIBUTE_UNUSED)
 {
         struct async_private_data data;
         snd_async_handler_t *ahandler;
         const snd_pcm_channel_area_t *my_areas;
         snd_pcm_uframes_t offset, frames, size;
         snd_pcm_sframes_t commitres;
         int err, count;

         data.samples = NULL;    /* we do not require the global sample 
area for direct write */
         data.areas = NULL;      /* we do not require the global areas 
for direct write */
         data.phase = 0;
        err = snd_async_add_pcm_handler(&ahandler, handle, 
async_direct_callback, &data);
         if (err < 0) {
                 printf("Unable to register async handler\n");
                 exit(EXIT_FAILURE);
         }
         for (count = 0; count < 2; count++) {
                 size = period_size;
                 while (size > 0) {
                         frames = size;
                         err = snd_pcm_mmap_begin(handle, &my_areas, 
&offset, &frames);
                         if (err < 0) {
                                 if ((err = xrun_recovery(handle, err)) 
< 0) {
                                         printf("MMAP begin avail error: 
%s\n", snd_strerror(err));
                                         exit(EXIT_FAILURE);
                                }
                        }
                         generate_sine(my_areas, offset, frames, 
&data.phase);
                         commitres = snd_pcm_mmap_commit(handle, offset, 
frames);
                         if (commitres < 0 || 
(snd_pcm_uframes_t)commitres != frames) {
                                 if ((err = xrun_recovery(handle, 
commitres >= 0 ? -EPIPE : commitres)) < 0) {
                                         printf("MMAP commit error: 
%s\n", snd_strerror(err));
                                         exit(EXIT_FAILURE);
                                 }
                         }
                         size -= frames;
                  }
         }
         err = snd_pcm_start(handle);
         if (err < 0) {
                 printf("Start error: %s\n", snd_strerror(err));
                 exit(EXIT_FAILURE);
         }

        /* because all other work is done in the signal handler,
            suspend the process */
         while (1) {
                 sleep(1);
         }
}

/*
*   Transfer method - direct write only
*/

static int direct_loop(snd_pcm_t *handle,
                        signed short *samples ATTRIBUTE_UNUSED,
                        snd_pcm_channel_area_t *areas ATTRIBUTE_UNUSED)
 {
         double phase = 0;
        const snd_pcm_channel_area_t *my_areas;
         snd_pcm_uframes_t offset, frames, size;
        snd_pcm_sframes_t avail, commitres;
         snd_pcm_state_t state;
         int err, first = 1;

         while (1) {
                 state = snd_pcm_state(handle);
                 if (state == SND_PCM_STATE_XRUN) {
                         err = xrun_recovery(handle, -EPIPE);
                         if (err < 0) {
                                printf("XRUN recovery failed: %s\n", 
snd_strerror(err));
                                 return err;
                         }
                         first = 1;
                } else if (state == SND_PCM_STATE_SUSPENDED) {
                        err = xrun_recovery(handle, -ESTRPIPE);
                         if (err < 0) {
                                 printf("SUSPEND recovery failed: %s\n", 
snd_strerror(err));
                                  return err;
                         }
                 }
                 avail = snd_pcm_avail_update(handle);
                 if (avail < 0) {
                         err = xrun_recovery(handle, avail);
                         if (err < 0) {
                                 printf("avail update failed: %s\n", 
snd_strerror(err));
                                 return err;
                         }
                         first = 1;
                         continue;
                 }
                 if (avail < period_size) {
                         if (first) {
                                 first = 0;
                                 err = snd_pcm_start(handle);
                                 if (err < 0) {
                                         printf("Start error: %s\n", 
snd_strerror(err));
                                         exit(EXIT_FAILURE);
                                 }
                         } else {
                                 err = snd_pcm_wait(handle, -1);
                                 if (err < 0) {
                                         if ((err = 
xrun_recovery(handle, err)) < 0) {
                                                 printf("snd_pcm_wait 
error: %s\n", snd_strerror(err));
                                                 exit(EXIT_FAILURE);
                                         }
                                         first = 1;
                                 }
                         }
                         continue;
                 }
                 size = period_size;
                 while (size > 0) {
                          frames = size;
                         err = snd_pcm_mmap_begin(handle, &my_areas, 
&offset, &frames);
                         if (err < 0) {
                                if ((err = xrun_recovery(handle, err)) < 
0) {
                                         printf("MMAP begin avail error: 
%s\n", snd_strerror(err));
                                         exit(EXIT_FAILURE);
                                 }
                                 first = 1;
                        }
                         generate_sine(my_areas, offset, frames, &phase);
                         commitres = snd_pcm_mmap_commit(handle, offset, 
frames);
                         if (commitres < 0 || 
(snd_pcm_uframes_t)commitres != frames) {
                                if ((err = xrun_recovery(handle, 
commitres >= 0 ? -EPIPE : commitres)) < 0) {
                                         printf("MMAP commit error: 
%s\n", snd_strerror(err));
                                         exit(EXIT_FAILURE);
                                 }
                                first = 1;
                         }
                         size -= frames;
                 }
         }
}

/*
*   Transfer method - direct write only using mmap_write functions
*/

static int direct_write_loop(snd_pcm_t *handle,
                              signed short *samples,
                             snd_pcm_channel_area_t *areas)
{
        double phase = 0;
         signed short *ptr;
         int err, cptr;

         while (1) {
                 generate_sine(areas, 0, period_size, &phase);
                ptr = samples;
                 cptr = period_size;
                 while (cptr > 0) {
                         err = snd_pcm_mmap_writei(handle, ptr, cptr);
                         if (err == -EAGAIN)
                                 continue;
                         if (err < 0) {
                                 if (xrun_recovery(handle, err) < 0) {
                                         printf("Write error: %s\n", 
snd_strerror(err));
                                         exit(EXIT_FAILURE);
                                }
                                break;  /* skip one period */
                        }
                         ptr += err * channels;
                         cptr -= err;
                 }
         }
}

struct transfer_method {
      const char *name;
      snd_pcm_access_t access;
      int (*transfer_loop)(snd_pcm_t *handle,
                           signed short *samples,
                           snd_pcm_channel_area_t *areas);
};

static struct transfer_method transfer_methods[] = {
         { "write", SND_PCM_ACCESS_RW_INTERLEAVED, write_loop },
         { "write_and_poll", SND_PCM_ACCESS_RW_INTERLEAVED, 
write_and_poll_loop },
         { "async", SND_PCM_ACCESS_RW_INTERLEAVED, async_loop },
         { "async_direct", SND_PCM_ACCESS_MMAP_INTERLEAVED, 
async_direct_loop },
         { "direct_interleaved", SND_PCM_ACCESS_MMAP_INTERLEAVED, 
direct_loop },
         { "direct_noninterleaved", SND_PCM_ACCESS_MMAP_NONINTERLEAVED, 
direct_loop },
         { "direct_write", SND_PCM_ACCESS_MMAP_INTERLEAVED, 
direct_write_loop },
         { NULL, SND_PCM_ACCESS_RW_INTERLEAVED, NULL }
};



static void help(void)
{
        int k;
         printf(
 "Usage: pcm [OPTION]... [FILE]...\n"
 "-h,--help      help\n"
 "-D,--device    playback device\n"
 "-r,--rate      stream rate in Hz\n"
 "-c,--channels  count of channels in stream\n"
 "-f,--frequency sine wave frequency in Hz\n"
 "-b,--buffer    ring buffer size in us\n"
 "-p,--period    period size in us\n"
 "-m,--method    transfer method\n"
 "-o,--format    sample format\n"
 "-v,--verbose   show the PCM setup parameters\n"
 "-n,--noresample  do not resample\n"
 "-e,--pevent    enable poll event after each period\n"
 "\n");
         printf("Recognized sample formats are:");
        for (k = 0; k < SND_PCM_FORMAT_LAST; ++k) {
                 const char *s = snd_pcm_format_name(k);
                 if (s)
                         printf(" %s", s);
         }
         printf("\n");
         printf("Recognized transfer methods are:");
         for (k = 0; transfer_methods[k].name; k++)
                 printf(" %s", transfer_methods[k].name);
         printf("\n");
}



int main (int argc, char *argv[])
{
           struct option long_option[] =
               {
                    {"help", 0, NULL, 'h'},
                    {"device", 1, NULL, 'd'},
                    {"rate", 1, NULL, 'r'},
                    {"channels", 1, NULL, 'c'},
                    {"frequency", 1, NULL, 'f'},
                    {"buffer", 1, NULL, 'b'},
                    {"period", 1, NULL, 'p'},
                    {"method", 1, NULL, 'm'},
                    {"format", 1, NULL, 'o'},
                    {"verbose", 1, NULL, 'v'},
                    {"noresample", 1, NULL, 'n'},
                    {"pevent", 1, NULL, 'e'},
                    {NULL, 0, NULL, 0},
               };
                             snd_pcm_t 
*handle;                            //ponteiro para pcm handle
               int err, morehelp;
               snd_pcm_hw_params_t *hwparams;                
//parametros de hardware
               snd_pcm_sw_params_t *swparams;                
//parametros de software
               int method = 0;
               signed short *samples;
               unsigned int chn;
               snd_pcm_channel_area_t *areas;

               //snd_pcm_hw_params_alloca(&hwparams);
               //snd_pcm_sw_params_alloca(&swparams);
                             morehelp = 0;
               while (1) {
                           int c;
                           if ((c = getopt_long(argc, argv, 
"hd:r:c:f:b:p:m:o:vne", long_option, NULL)) < 0)
                                   break;
                           switch(c) {
                           case 'h':
                                       morehelp++;
                                       break;
                           case 'd':
                                       device = strdup(optarg);
                                       break;
                           case 'r':
                                       rate = atoi(optarg);
                                       rate = rate < 4000 ? 4000 : rate;
                                       rate = rate > 196000 ? 19600 : rate;
                                       break;
                        case 'c':
                             channels = atoi(optarg);
                             channels = channels < 1 ? 1 : channels;
                             channels = channels > 1024 ? 1024 : channels;
                             break;
                    case 'f':
                             freq = atoi(optarg);
                             freq = freq < 50 ? 50 : freq;
                             freq = freq > 5000 ? 5000 : freq;
                             break;
                    case 'b':
                             buffer_time = atoi(optarg);
                             buffer_time = buffer_time < 1000 ? 1000 : 
buffer_time;
                             buffer_time = buffer_time > 1000000 ? 
1000000 : buffer_time;
                             break;
                    case 'p':
                             period_time = atoi(optarg);
                             period_time = period_time < 1000 ? 1000 : 
period_time;
                             period_time = period_time > 1000000 ? 
1000000 : period_time;
                             break;
                    case 'm':
                             for (method = 0; 
transfer_methods[method].name; method++)
                                             if 
(!strcasecmp(transfer_methods[method].name, optarg))
                                             break;
                             if (transfer_methods[method].name == NULL)
                                     method = 0;
                             break;
                    case 'o':
                             for (format = 0; format < 
SND_PCM_FORMAT_LAST; format++) {
                                     const char *format_name = 
snd_pcm_format_name(format);
                                     if (format_name)
                                             if 
(!strcasecmp(format_name, optarg))
                                             break;
                             }
                             if (format == SND_PCM_FORMAT_LAST)
                                    format = SND_PCM_FORMAT_S16;
                             break;
                    case 'v':
                             verbose = 1;
                             break;
                    case 'n':
                             resample = 0;
                             break;
                     case 'e':
                             period_event = 1;
                             break;
                    }//switch
             }//while
                         if(morehelp) {
                         help();
                         return 0;
             }

               //cria um novo output objeto
               err = snd_output_stdio_attach(&output, &stdout, 0);
               if (err < 0) {
                       printf("Output failed: %s\n", snd_strerror(err));
                       return 0;
               }
                             printf("Playback device is %s\n", device);
               printf("Stream parameters are %iHz, %s, %i channels\n", 
rate, snd_pcm_format_name(format), channels);
               printf("sine wave rate is %i %.4fHz\n", freq);
               printf("Using transfer method: %s\n", 
transfer_methods[method].name);
                             if ((err = snd_pcm_open(&handle, device, 
SND_PCM_STREAM_PLAYBACK, 0)) < 0) {
                       printf("Playback open error: %s\n", 
snd_strerror(err));
                       return 0;
               }
                             if ((err = set_hwparams(handle, hwparams, 
transfer_methods[method].access)) < 0) {
                 printf("Setting of hwparams failed: %s\n", 
snd_strerror(err));
                 exit(EXIT_FAILURE);
           }
           if ((err = set_swparams(handle, swparams)) < 0) {
                 printf("Setting of swparams failed: %s\n", 
snd_strerror(err));
                 exit(EXIT_FAILURE);
          }

           if (verbose > 0)
                 snd_pcm_dump(handle, output);
                         samples = malloc((period_size * channels * 
snd_pcm_format_physical_width(format)) / 8);
           if (samples == NULL) {
                 printf("No enough memory\n");
                 exit(EXIT_FAILURE);
           }
                   areas = calloc(channels, 
sizeof(snd_pcm_channel_area_t));
           if (areas == NULL) {
                 printf("No enough memory\n");
                 exit(EXIT_FAILURE);
           }
           for (chn = 0; chn < channels; chn++) {
                 areas[chn].addr = samples;
                 areas[chn].first = chn * 
snd_pcm_format_physical_width(format);
                 areas[chn].step = channels * 
snd_pcm_format_physical_width(format);
            }

           err = transfer_methods[method].transfer_loop(handle, samples, 
areas);
           if (err < 0)
                 printf("Transfer failed: %s\n", snd_strerror(err));

           free(areas);
           free(samples);
           snd_pcm_close(handle);
           return 0;
}


Thanks in advance;

-- 
Tks!

-------------------

Guilherme Longo
Dept. Eng. da Computação
Unaerp

Linux User - #484927

*Before Asking
http://www.istf.com.br/?page=perguntas

!- I'd rather die on my feet than live on my knees -!



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