[alsa-devel] segfault when setting swparams! help

Guilherme grlongo.ireland at gmail.com
Fri Jun 19 09:27:58 CEST 2009


Mates...

I am getting a segfault when running my app:

This is the part of the code where I am getting the error:

            if ((err = set_swparams(handle, swparams)) < 0) {
                  printf("Setting of swparams failed: %s\n", 
snd_strerror(err));
                  exit(EXIT_FAILURE);
           }

That is the gdb output:  (*The full program code's been posted below the 
debug output)

Starting program: /home/guilherme/Experimentos/PCM
[Thread debugging using libthread_db enabled]
[New Thread 0xb7c896c0 (LWP 3391)]
[Switching to Thread 0xb7c896c0 (LWP 3391)]

Breakpoint 1, main (argc=1, argv=0xbfa27da4) at pcm.c:777
777                    };
(gdb) n
783                    int method = 0;
(gdb) n
791                    morehelp = 0;
(gdb) n
794                                if ((c = getopt_long(argc, argv, 
"hd:r:c:f:b:p:m:o:vne", long_option, NULL)) < 0)
(gdb) nn
Undefined command: "nn".  Try "help".
(gdb) n
857                  if(morehelp) {
(gdb) n
863                    err = snd_output_stdio_attach(&output, &stdout, 0);
(gdb) n
864                    if (err < 0) {
(gdb) n
869                    printf("Playback device is %s\n", device);
(gdb) n
Playback device is default
870                    printf("Stream parameters are %iHz, %s, %i 
channels\n", rate, snd_pcm_format_name(format), channels);
(gdb) n
Stream parameters are 48000Hz, S16_LE, 1 channels
871                    printf("sine wave rate is %i %.4fHz\n", freq);
(gdb) n
sine wave rate is 0 0.0000Hz
872                    printf("Using transfer method: %s\n", 
transfer_methods[method].name);
(gdb) n
Using transfer method: write
874                    if ((err = snd_pcm_open(&handle, device, 
SND_PCM_STREAM_PLAYBACK, 0)) < 0) {
(gdb) n
879                    if ((err = set_hwparams(handle, hwparams, 
transfer_methods[method].access)) < 0) {
(gdb) n

Program received signal SIGSEGV, Segmentation fault.
0xb7d47e3f in memset () from /lib/libc.so.6
(gdb) Quit
(gdb) quit
The program is running.  Exit anyway? (y or n)





That  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 = "default";                       //playback device 
aplay -l
static snd_pcm_format_t format = SND_PCM_FORMAT_S16;   //sample format 
unsigned 16 bit endian
static unsigned int rate = 48000;                      //stream rate
static unsigned int channels = 1;                       //contagem dos 
canais
static unsigned int buffer_time = 500;              //ring buffer length 
on us
static unsigned int period_time = 100;              //period time in us
static double freq = 440;                              // 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;
}



Any ideas of what might be happening?? I've been looking for a 
reasonable explanation but i don't find any related error o online.

Tks in advanced!

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 -!



Takashi Iwai wrote:
> At Fri, 19 Jun 2009 02:50:35 +0300,
> Maxim Levitsky wrote:
>   
>> Hi,
>>
>> Due to lack of time, I didn't update kernel on my desktop system.
>> Now I notice that analog loopback go removed. Why?
>>     
>
> Because it harms than helps more often.  I've got tons of bug reports
> and been upset just because users blindly set "Analog Loopback" mixer
> switch and lost their sound output.  This is no mixer element that
> behaves intuitively -- it shuts out PCM output instead of adding the
> analog loopback like other hardwares.
>
> The feature is still available, though.  You just need to give the
> driver an instruction via sysfs.  Namely, write to sysfs files
> corresponding to the IDT codec like
> 	# echo "loopback yes" > /sys/class/sound/hwC0D0/hints
> 	# echo 1 > /sys/class/sound/hwC0D0/reconfig
> Then the driver will reconfigure with the loopback mixer element.
> 	
> I have a patch series to add this with a "patch" firmware file to
> make it easier, which I'm going to send an RFC to this ML soon later.
> Take a look at topic/hda-patch branch on sound-unstable tree.
>
>
> thanks,
>
> Takashi
> _______________________________________________
> Alsa-devel mailing list
> Alsa-devel at alsa-project.org
> http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
>
>   


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