Daniel Mack <zonque <at> gmail.com> writes:

Without providing any code, I guess nobody on this list will be able to help you.

Daniel

OK. Here is the essential part of my code - settings and write to ALSA:

PlayThread() { ...

/********************************* SET PARAMS ******************/         /* Set HW Parameters, based on .wav header settings */         ...            /* APLAY settings */          if (buffer_time == 0 && buffer_frames == 0)             {             iCheckErrorState = snd_pcm_hw_params_get_buffer_time_max(pcmHwParameterCfg, &buffer_time, 0);             if (iCheckErrorState < 0)                {                iStatus = -1; /* set erroneous state */                }             if (buffer_time > 500000)                {                buffer_time = 500000;                }             }          if (period_time == 0 && period_frames == 0)             {             if (buffer_time > 0)                {                period_time = buffer_time / 4;                }             else                {                period_frames = buffer_frames / 4;                }             }          if (period_time > 0)             {                period_time = 500000;    /* restrict /smaller period time */             iCheckErrorState = snd_pcm_hw_params_set_period_time_near(pPcmPlayHandle, pcmHwParameterCfg,                                                          &period_time, 0);             }          else             {             iCheckErrorState = snd_pcm_hw_params_set_period_size_near(pPcmPlayHandle, pcmHwParameterCfg,                                                          &period_frames, 0);             }          if (iCheckErrorState < 0)             {             iStatus = -1; /* set erroneous state */             }          if (buffer_time > 0)             {             iCheckErrorState = snd_pcm_hw_params_set_buffer_time_near(pPcmPlayHandle, pcmHwParameterCfg,                                                          &buffer_time, 0);             }          else             {             iCheckErrorState = snd_pcm_hw_params_set_buffer_size_near(pPcmPlayHandle, pcmHwParameterCfg,                                                          &buffer_frames);             }          if (iCheckErrorState < 0)             {             iStatus = -1; /* set erroneous state */             }

iCheckErrorState = snd_pcm_hw_params(pPcmPlayHandle, pcmHwParameterCfg);          if (iCheckErrorState != 0)             {             iStatus = -1;             }          snd_pcm_hw_params_get_period_size(pcmHwParameterCfg, &pcmPeriodSize, 0);          snd_pcm_hw_params_get_buffer_size(pcmHwParameterCfg, &pcmBufferSize);

fprintf(stderr,"Period size = %lu ; Buffer size = %lu \n", pcmPeriodSize, pcmBufferSize);

if (pcmPeriodSize == pcmBufferSize)             {             fprintf(stderr,"Can't use period equal to buffer size (%lu == %lu)", pcmPeriodSize, pcmBufferSize);             }

snd_pcm_sw_params_current(pPcmPlayHandle, pcmSWParameterCfg);          if (avail_min < 0)             {             n = pcmPeriodSize;             }          else             {             n = (double) rate * avail_min / 1000000;             }          iCheckErrorState = snd_pcm_sw_params_set_avail_min(pPcmPlayHandle, pcmSWParameterCfg, n);                    /* round up to closest transfer boundary */          n = pcmBufferSize;          if (start_delay <= 0)             {             start_threshold = n + (double) rate * start_delay / 1000000;             }          else             {             start_threshold = (double) rate * start_delay / 1000000;             }          if (start_threshold < 1)             {             start_threshold = 1;             }          if (start_threshold > n)             {             start_threshold = n;             }

iCheckErrorState = snd_pcm_sw_params_set_start_threshold(pPcmPlayHandle, pcmSWParameterCfg, start_threshold);          if (iCheckErrorState < 0)             {             iStatus = -1; /* set erroneous state */             }

fprintf(stderr,"Start threshold = %lu \n",start_threshold);

if (stop_delay <= 0)             {             stop_threshold = pcmBufferSize + (double) rate * stop_delay / 1000000;             }          else             {             stop_threshold = (double) rate * stop_delay / 1000000;             }

iCheckErrorState = snd_pcm_sw_params_set_stop_threshold(pPcmPlayHandle, pcmSWParameterCfg, stop_threshold);          if (iCheckErrorState < 0)             {             iStatus = -1; /* set erroneous state */             }

if (snd_pcm_sw_params(pPcmPlayHandle, pcmSWParameterCfg) < 0)             {             fprintf(stderr,"Unable to install sw parameters, exit thread \n");             iStatus = -1; /* set erroneous state */             }

fprintf(stderr,"Play ThreadID [%lu]: after parmas ended\n", pthread_self());      /* END APLAY settings */          /*********************************END SET PARAMS ******************/          /* Check if the Settings were correctly done or not */          if (iStatus < 0)             {             fprintf(stderr,"Could not SET correctly the wav settings! \n");         /* ... do something */             }          else             {             /* Finished operation with Settings, continue processing */                  /*Now we've set up our device, but we still can't write to it. There's one last step we have to take: prepare the device */                  snd_pcm_prepare (pPcmPlayHandle);                                            /* NOTE: cannot use to malloc the entire wav file size, as this leads to: frequent overrun (more data in output buffer),                   * and the User-Space app runtime memory is increased with wav file size; Hence, is better to use the ALSA pcm buffer sizes. */

iBufferSize = pcmBufferSize;

TimeStamp("Play ThreadID [%lu]: before malloc\n", pthread_self());             fprintf(stderr,"About to allocate %u buffer...\n", iBufferSize);

pu8WavDataBuf = (uint8*) malloc( (size_t) iBufferSize);             if (pu8WavDataBuf != NULL)                {                   /* Data allocation successful continue with play... */                fprintf(stderr,"Done allocating the buffer, start execute ALSA play sequence...\n");

size_t offset = 0;                int remaining = WavSoundSize;

Wavfp = fopen(WavPathAndName, "r");                if (Wavfp != NULL)                   {                   /* Wav FILE opened OK, continue reading the data and send it to ALSA driver */                   TimeStamp("Play ThreadID [%lu]: before reading/writing\n", pthread_self());                   while (remaining > 0)                      {                         /* READ DATA into local buffer */                      /* Firstly, read a block of data into buffer */                      /********* READ DATA ********/                      /* Normal read from wav file, with a complete a buffer size */                         iStatus = fread(pu8WavDataBuf, sizeof(uint8), iBufferSize , Wavfp);                      /********** END READ DATA ****************/

/* Secondly, output that buffer to ALSA driver */                      iStatus = snd_pcm_writei(pPcmPlayHandle, pu8WavDataBuf, iBufferSize / (stHWSettings.format * stHWSettings.channels) );                      if (iStatus == -EAGAIN || (iStatus >= 0 && ( (size_t)iStatus < iBufferSize / (stHWSettings.format * stHWSettings.channels)  ) ))                         {                         /* The ALSA ring buffer is full, wait some small time to flush parts of data, so we can fill it with rest of .wav data */                         fprintf(stderr,"The ALSA ring buffer is full, wait some small time to flush parts of data \n");                         snd_pcm_wait(pPcmPlayHandle, 10);                         }                      else                         {                         if (iStatus == -EPIPE)                            {                            /* In some cases, it might happen that this thread does not feed new samples in time to alsa-lib (due to high CPU usage - thread interrupted often -                             * or large delay between consecutive writei() calls). Therefore, we must prepare/recover the PCM handle for next usage.                             */

/* Print delay time */                             snd_pcm_status_t *status;                             snd_pcm_status_alloca(&status);                             if ((snd_pcm_status(pPcmPlayHandle, status))<0) {                                 fprintf(stderr, "some error \n");                             }                             struct timespec now, diff, tstamp;                             clock_gettime(CLOCK_MONOTONIC, &now);                             snd_pcm_status_get_trigger_htstamp(status, &tstamp);                             timermsub(&now, &tstamp, &diff);                             fprintf(stderr,"underrun!!! (at least %.3f ms long)\n", diff.tv_sec * 1000 + diff.tv_nsec / 10000000.0);

fprintf(stderr,"Underrun encountered: application didn't sent enough data to the ALSA buffer, status = %d \n", iStatus);                            iStatus = snd_pcm_recover(pPcmPlayHandle,iStatus,0 );                            }                         else                            {                            if (iStatus == -ESTRPIPE)                               {                 /* ignore it */                               }                            else                               {                               if (iStatus < 0)                                  {                        /* ignore it */                                  }                               else                                  {                                  /* Write performed OK */                                  }                               }                            }                         }                      /* Use the pcm_avail_update() only for checking buffer playback fill level - not for SYNCHRONISATION */                      snd_pcm_sframes_t pcmAvailBytes;                      pcmAvailBytes = snd_pcm_avail_update(pPcmPlayHandle);                                            offset = offset +  ( iStatus * (stHWSettings.format * stHWSettings.channels));                      remaining = remaining -  ( iStatus * (stHWSettings.format * stHWSettings.channels));                                             fprintf(stderr,"Writei() ended, bytes written = %d, available bytes to be written = %lu\n", iStatus, pcmAvailBytes);                      }

TimeStamp("Play ThreadID [%lu]: after reading/writing fully ended\n", pthread_self());                   /* Finished reading the wav file, now it's time to close it */                   fclose(Wavfp);                      /* Done the complete output, now drain/reset the ALSA device */                      snd_pcm_nonblock(pPcmPlayHandle, 0);                      snd_pcm_drain(pPcmPlayHandle);                      snd_pcm_nonblock(pPcmPlayHandle, 0); ... }

On 23.11.2012 11:35, Sandulescu Bogdan wrote:

...

Daniel Mack <zonque <at> gmail.com> writes:

...

Without providing any code, I guess nobody on this list will be able to help you.

Daniel

OK. Here is the essential part of my code - settings and write to ALSA:

It's not about the userspace code in the first place but the kernel part.

I guess you are based on a BSP kernel that the vendor of the chip/module/board you are using provides. For whatever reason, this vendor has decided to not push its code to the mainline kernel but keep changes in a private repository.

While this is a common approach, your vendor is the only instance in the game that is in charge of supporting you here. The community can't, as the code has not been shared for discussion and integration in mainline.

Daniel

Hello Daniel,

Thank you for your answer. Initially I thought I should share my app, as every information I got regarding underruns was that the application is not feeding data fast enough - hence I thought it was my application's fault.

Considering your precise answer, I will try to get support directly from the module vendor.

Yours,     Bogdan