C++ snd_pcm_sw_params_set_avail_min函数代码示例

static void alsa_set_sw_params(struct alsa_dev *dev, snd_pcm_t *handle,
			       int period, int thres)
{
	int ret;
	snd_pcm_sw_params_t *sw_params;

	ret = snd_pcm_sw_params_malloc(&sw_params);
	if (ret < 0)
		syslog_panic("Cannot allocate software parameters: %s\n",
			     snd_strerror(ret));
	ret = snd_pcm_sw_params_current(handle, sw_params);
	if (ret < 0)
		syslog_panic("Cannot initialize software parameters: %s\n",
			     snd_strerror(ret));
	ret = snd_pcm_sw_params_set_avail_min(handle, sw_params, period);
	if (ret < 0)
		syslog_panic("Cannot set minimum available count: %s\n",
			     snd_strerror(ret));
	if (thres) {
		ret = snd_pcm_sw_params_set_start_threshold(handle, sw_params,
							    period);
		if (ret < 0)
			syslog_panic("Cannot set start mode: %s\n",
				     snd_strerror(ret));
		
	}
	ret = snd_pcm_sw_params(handle, sw_params);
	if (ret < 0)
		syslog_panic("Cannot set software parameters: %s\n",
			     snd_strerror(ret));
	snd_pcm_sw_params_free(sw_params);
}

static int set_sw_params(snd_pcm_t *pcm,
                         snd_pcm_sw_params_t *sw_params,
                         snd_spcm_xrun_type_t xrun_type)
{
    int err;

    err = snd_pcm_sw_params_current(pcm, sw_params);
    if (err < 0)
        return err;
    err = snd_pcm_sw_params_set_start_threshold(pcm, sw_params, (pcm->buffer_size / pcm->period_size) * pcm->period_size);
    if (err < 0)
        return err;
    err = snd_pcm_sw_params_set_avail_min(pcm, sw_params, pcm->period_size);
    if (err < 0)
        return err;
    switch (xrun_type) {
    case SND_SPCM_XRUN_STOP:
        err = snd_pcm_sw_params_set_stop_threshold(pcm, sw_params, pcm->buffer_size);
        break;
    case SND_SPCM_XRUN_IGNORE:
        err = snd_pcm_sw_params_set_stop_threshold(pcm, sw_params, pcm->boundary);
        break;
    default:
        return -EINVAL;
    }
    if (err < 0)
        return err;
    err = snd_pcm_sw_params_set_xfer_align(pcm, sw_params, 1);
    if (err < 0)
        return err;
    err = snd_pcm_sw_params(pcm, sw_params);
    if (err < 0)
        return err;
    return 0;
}

int set_swparams(snd_pcm_t *handle, snd_pcm_sw_params_t *swparams)
{
        int err;

        /* get the current 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;
        }
        /* start the transfer when the buffer is almost full: */
        /* (buffer_size / avail_min) * avail_min */
        //err = snd_pcm_sw_params_set_start_threshold(handle, swparams, (buffer_size / period_size) * period_size);
        err = snd_pcm_sw_params_set_start_threshold(handle, swparams, period_size * periods - arnold_frame_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 */
        err = snd_pcm_sw_params_set_avail_min(handle, swparams, arnold_frame_size);
        if (err < 0) {
                printf("Unable to set avail min for playback: %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;
}

snd_pcm_t *open_pcm(char *pcm_name) {

    snd_pcm_t *playback_handle;
    snd_pcm_hw_params_t *hw_params;
    snd_pcm_sw_params_t *sw_params;
            
    if (snd_pcm_open (&playback_handle, pcm_name, SND_PCM_STREAM_PLAYBACK, 0) < 0) {
        fprintf (stderr, "cannot open audio device %s\n", pcm_name);
        exit (1);
    }
    snd_pcm_hw_params_alloca(&hw_params);
    snd_pcm_hw_params_any(playback_handle, hw_params);
    snd_pcm_hw_params_set_access(playback_handle, hw_params, SND_PCM_ACCESS_RW_INTERLEAVED);
    snd_pcm_hw_params_set_format(playback_handle, hw_params, SND_PCM_FORMAT_S16_LE);
    snd_pcm_hw_params_set_rate_near(playback_handle, hw_params, 44100, 0);
    snd_pcm_hw_params_set_channels(playback_handle, hw_params, 2);
    snd_pcm_hw_params_set_periods(playback_handle, hw_params, 2, 0);
    snd_pcm_hw_params_set_period_size(playback_handle, hw_params, BUFSIZE, 0);
    snd_pcm_hw_params(playback_handle, hw_params);
    snd_pcm_sw_params_alloca(&sw_params);
    snd_pcm_sw_params_current(playback_handle, sw_params);
    snd_pcm_sw_params_set_avail_min(playback_handle, sw_params, BUFSIZE);
    snd_pcm_sw_params(playback_handle, sw_params);
    return(playback_handle);
}

static void audio_renderer_init() {
  int rc;
  decoder = opus_decoder_create(SAMPLE_RATE, CHANNEL_COUNT, &rc);

  snd_pcm_hw_params_t *hw_params;
  snd_pcm_sw_params_t *sw_params;
  snd_pcm_uframes_t period_size = FRAME_SIZE * CHANNEL_COUNT * 2;
  snd_pcm_uframes_t buffer_size = 12 * period_size;
  unsigned int sampleRate = SAMPLE_RATE;

  /* Open PCM device for playback. */
  CHECK_RETURN(snd_pcm_open(&handle, audio_device, SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK))

  /* Set hardware parameters */
  CHECK_RETURN(snd_pcm_hw_params_malloc(&hw_params));
  CHECK_RETURN(snd_pcm_hw_params_any(handle, hw_params));
  CHECK_RETURN(snd_pcm_hw_params_set_access(handle, hw_params, SND_PCM_ACCESS_RW_INTERLEAVED));
  CHECK_RETURN(snd_pcm_hw_params_set_format(handle, hw_params, SND_PCM_FORMAT_S16_LE));
  CHECK_RETURN(snd_pcm_hw_params_set_rate_near(handle, hw_params, &sampleRate, NULL));
  CHECK_RETURN(snd_pcm_hw_params_set_channels(handle, hw_params, CHANNEL_COUNT));
  CHECK_RETURN(snd_pcm_hw_params_set_buffer_size_near(handle, hw_params, &buffer_size));
  CHECK_RETURN(snd_pcm_hw_params_set_period_size_near(handle, hw_params, &period_size, NULL));
  CHECK_RETURN(snd_pcm_hw_params(handle, hw_params));
  snd_pcm_hw_params_free(hw_params);

  /* Set software parameters */
  CHECK_RETURN(snd_pcm_sw_params_malloc(&sw_params));
  CHECK_RETURN(snd_pcm_sw_params_current(handle, sw_params));
  CHECK_RETURN(snd_pcm_sw_params_set_start_threshold(handle, sw_params, buffer_size - period_size));
  CHECK_RETURN(snd_pcm_sw_params_set_avail_min(handle, sw_params, period_size));
  CHECK_RETURN(snd_pcm_sw_params(handle, sw_params));
  snd_pcm_sw_params_free(sw_params);

  CHECK_RETURN(snd_pcm_prepare(handle));
}

int VoiceStreamer::setparams_set(snd_pcm_t *handle, snd_pcm_hw_params_t *params,
      snd_pcm_sw_params_t *swparams, const char *id) {
   int err;
   snd_pcm_uframes_t val;

   if ((err = snd_pcm_hw_params(handle, params)) < 0) {
      printf("Unable to set hw params for %s: %s\n", id, snd_strerror(err));
      return err;
   }
   if ((err = snd_pcm_sw_params_current(handle, swparams)) < 0) {
      printf("Unable to determine current swparams for %s: %s\n", id,
            snd_strerror(err));
      return err;
   }
   if ((err = snd_pcm_sw_params_set_start_threshold(handle, swparams, 
               0x7fffffff)) < 0) {
      printf("Unable to set start threshold mode for %s: %s\n", id,
            snd_strerror(err));
      return err;
   }
   val = 4;
   if ((err = snd_pcm_sw_params_set_avail_min(handle, swparams, val)) < 0) {
      printf("Unable to set sw params for %s: %s\n", id, snd_strerror(err));
      return err;
   }

   return 0;
}

// returns 1 if successful
int setSWParams(AlsaPcmInfo* info) {
    int ret;

    /* get the current swparams */
    ret = snd_pcm_sw_params_current(info->handle, info->swParams);
    if (ret < 0) {
        ERROR1("Unable to determine current swparams: %s\n", snd_strerror(ret));
        return FALSE;
    }
    /* never start the transfer automatically */
    if (!setStartThresholdNoCommit(info, FALSE /* don't use threshold */)) {
        return FALSE;
    }

    /* allow the transfer when at least period_size samples can be processed */
    ret = snd_pcm_sw_params_set_avail_min(info->handle, info->swParams, info->periodSize);
    if (ret < 0) {
        ERROR1("Unable to set avail min for playback: %s\n", snd_strerror(ret));
        return FALSE;
    }
    /* align all transfers to 1 sample */
    ret = snd_pcm_sw_params_set_xfer_align(info->handle, info->swParams, 1);
    if (ret < 0) {
        ERROR1("Unable to set transfer align: %s\n", snd_strerror(ret));
        return FALSE;
    }
    /* write the parameters to the playback device */
    ret = snd_pcm_sw_params(info->handle, info->swParams);
    if (ret < 0) {
        ERROR1("Unable to set sw params: %s\n", snd_strerror(ret));
        return FALSE;
    }
    return TRUE;
}

int AudioAlsa::setSWParams()
{
	int err;

	// get the current swparams
	if( ( err = snd_pcm_sw_params_current( m_handle, m_swParams ) ) < 0 )
	{
		printf( "Unable to determine current swparams for playback: %s"
						"\n", snd_strerror( err ) );
		return err;
	}

	// start the transfer when a period is full
	if( ( err = snd_pcm_sw_params_set_start_threshold( m_handle,
					m_swParams, m_periodSize ) ) < 0 )
	{
		printf( "Unable to set start threshold mode for playback: %s\n",
							snd_strerror( err ) );
		return err;
	}

	// allow the transfer when at least m_periodSize samples can be
	// processed
	if( ( err = snd_pcm_sw_params_set_avail_min( m_handle, m_swParams,
							m_periodSize ) ) < 0 )
	{
		printf( "Unable to set avail min for playback: %s\n",
							snd_strerror( err ) );
		return err;
	}

	// align all transfers to 1 sample
	
#if SND_LIB_VERSION < ((1<<16)|(0)|16)
	if( ( err = snd_pcm_sw_params_set_xfer_align( m_handle,
							m_swParams, 1 ) ) < 0 )
	{
		printf( "Unable to set transfer align for playback: %s\n",
							snd_strerror( err ) );
		return err;
	}
#endif

	// write the parameters to the playback device
	if( ( err = snd_pcm_sw_params( m_handle, m_swParams ) ) < 0 )
	{
		printf( "Unable to set sw params for playback: %s\n",
							snd_strerror( err ) );
		return err;
	}

	return 0;	// all ok
}

static void set_params(void)
{
	hwparams.format=SND_PCM_FORMAT_S16_LE;
        hwparams.channels=2;
        hwparams.rate=44100;

	snd_pcm_hw_params_t *params;
	snd_pcm_sw_params_t *swparams;

        snd_pcm_hw_params_alloca(&params);
	snd_pcm_sw_params_alloca(&swparams);	

	snd_pcm_hw_params_any(handle, params);
	snd_pcm_hw_params_set_format(handle, params, hwparams.format);
	snd_pcm_hw_params_set_channels(handle, params, hwparams.channels);
	snd_pcm_hw_params_set_rate_near(handle, params, &hwparams.rate, 0);

	buffer_time=0;
	snd_pcm_hw_params_get_buffer_time_max(params,&buffer_time, 0);

	period_time=125000;
	snd_pcm_hw_params_set_period_time_near(handle, params,&period_time, 0);

	buffer_time = 500000;
	snd_pcm_hw_params_set_buffer_time_near(handle, params, &buffer_time, 0);
	
	/*monotonic = */snd_pcm_hw_params_is_monotonic(params);
        /*can_pause = */snd_pcm_hw_params_can_pause(params);

	
	printf("sizeof(params) : %d\n",sizeof(params));

        snd_pcm_hw_params(handle, params);

        snd_pcm_uframes_t buffer_size;
	snd_pcm_hw_params_get_period_size(params, &chunk_size, 0);

	size_t n=chunk_size;

	snd_pcm_sw_params_set_avail_min(handle, swparams, n);


	snd_pcm_uframes_t start_threshold, stop_threshold;	
	start_threshold=22050;
	snd_pcm_sw_params_set_start_threshold(handle, swparams, start_threshold);
	stop_threshold=22050;
	snd_pcm_sw_params_set_stop_threshold(handle, swparams, stop_threshold);
	
	snd_pcm_format_physical_width(hwparams.format);
	
}

void mixer_open()
{
	memset(&channels, 0, sizeof(channels));
	int err = snd_pcm_open(&pcm, "default", SND_PCM_STREAM_PLAYBACK, 0);
	if (err < 0)
	{
		printf("Failed to open pcm device: %s\n", snd_strerror(err));
		exit(1);
	}
	
	unsigned int rate = 44100;
	snd_pcm_hw_params_t *hw_params = 0;
	snd_pcm_hw_params_alloca(&hw_params);
	snd_pcm_hw_params_any(pcm, hw_params);
	snd_pcm_hw_params_set_rate_resample(pcm, hw_params, 0);
	snd_pcm_hw_params_set_access(pcm, hw_params, SND_PCM_ACCESS_RW_INTERLEAVED);
	snd_pcm_hw_params_set_format(pcm, hw_params, SND_PCM_FORMAT_S16_LE);
	snd_pcm_hw_params_set_rate_near(pcm, hw_params, &rate, 0);
	snd_pcm_hw_params_set_channels(pcm, hw_params, 2);
	snd_pcm_hw_params_set_period_size(pcm, hw_params, BUFFER_SIZE, 0);
	snd_pcm_hw_params_set_buffer_size(pcm, hw_params, BUFFER_SIZE * 4);
	
	err = snd_pcm_hw_params(pcm, hw_params);
	if (err < 0)
	{
		printf("Failed to apply pcm hardware settings: %s\n", snd_strerror(err));
		exit(1);
	}
	
	snd_pcm_sw_params_t *sw_params = 0;
	snd_pcm_sw_params_alloca(&sw_params);
	snd_pcm_sw_params_current(pcm, sw_params);
	snd_pcm_sw_params_set_avail_min(pcm, sw_params, BUFFER_SIZE * 4);
	err = snd_pcm_sw_params(pcm, sw_params);
	if (err < 0)
	{
		printf("Failed to apply pcm software settings: %s\n", snd_strerror(err));
		exit(1);
	}
	
	err = snd_pcm_prepare(pcm);
	if (err < 0)
	{
		printf("Failed to prepare pcm interface: %s\n", snd_strerror(err));
		exit(1);
	}
	
	memset(delay_left, 0, sizeof(delay_left));
	memset(delay_right, 0, sizeof(delay_right));
}

static int setparams_set(snd_pcm_t *handle,
                         snd_pcm_hw_params_t *params,
                         snd_pcm_sw_params_t *swparams,
                         snd_pcm_uframes_t start_treshold,
                         const char *id)
{
    int err;

    err = snd_pcm_hw_params(handle, params);
    if (err < 0) {
        fprintf(error_fp, "alsa: Unable to set hw params for %s: %s\n",
                id, snd_strerror(err));
        return err;
    }
    err = snd_pcm_sw_params_current(handle, swparams);
    if (err < 0) {
        fprintf(error_fp, "alsa: Unable to determine current swparams for %s: %s\n",
                id, snd_strerror(err));
        return err;
    }
    err = snd_pcm_sw_params_set_start_threshold(handle, swparams,
            start_treshold);
    if (err < 0) {
        fprintf(error_fp, "alsa: Unable to set start threshold mode for %s: %s\n",
                id, snd_strerror(err));
        return err;
    }

    err = snd_pcm_sw_params_set_avail_min(handle, swparams, 4);
    if (err < 0) {
        fprintf(error_fp, "alsa: Unable to set avail min for %s: %s\n",
                id, snd_strerror(err));
        return err;
    }

    err = snd_pcm_sw_params_set_tstamp_mode(handle, swparams, SND_PCM_TSTAMP_ENABLE);
    if (err < 0) {
        fprintf(error_fp, "alsa: Unable to enable timestamps for %s: %s\n",
                id, snd_strerror(err));
    }

    err = snd_pcm_sw_params(handle, swparams);
    if (err < 0) {
        fprintf(error_fp, "alsa: Unable to set sw params for %s: %s\n",
                id, snd_strerror(err));
        return err;
    }
    return 0;
}

/**************************************************************************************
 * set_swparams
 * history: (1) 2014 03 30 mhb
 *
 **************************************************************************************/
static int set_swparams(snd_pcm_t *handle, 
                        snd_pcm_sw_params_t *swparams)
{
    int err;
    /* get the current swparams */
    err = snd_pcm_sw_params_current(handle, swparams);
    if (err < 0) 
    {
        printf("Unable to determine current swparams : %s\n", snd_strerror(err));
        return err;
    }
    /* start the transfer when the buffer is almost full: */
    /* (buffer_size / avail_min) * avail_min */
    err = snd_pcm_sw_params_set_start_threshold(handle, swparams, (buffer_size / period_size) * period_size);
    //err = snd_pcm_sw_params_set_start_threshold(handle, swparams, 3*period_size);// mhb|  修改此值，太小程序会卡死
    if (err < 0) 
    {
        printf("Unable to set start threshold mode : %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);
    //err = snd_pcm_sw_params_set_avail_min(handle, swparams, 0);//mhb
    if (err < 0) 
    {
        printf("Unable to set avail min : %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 : %s\n", snd_strerror(err));
        return err;
    }
    return 0;
}

int
set_mic_swparams(snd_pcm_t *handle) 
{
    // set software params

    snd_pcm_sw_params_t *swparams;
    snd_pcm_sw_params_alloca(&swparams);

    /* get the current swparams */
    int ret = snd_pcm_sw_params_current(handle, swparams);
    if (ret < 0) {
        fprintf(stderr, 
	    "Unable to determine current swparams for mic: %s\n", 
	    snd_strerror(ret));
        return ret;
    }

    /* allow transfer when at least period_frames can be processed */

    ret = snd_pcm_sw_params_set_avail_min(handle, swparams, 
	get_period_frames(handle));

    if (ret < 0) {
        fprintf(stderr, "Unable to set avail min for mic: %s\n", 
	    snd_strerror(ret));
        return ret;
    }

    /* align all transfers to 1 sample */
    ret = snd_pcm_sw_params_set_xfer_align(handle, swparams, 1);
    if (ret < 0) {
        fprintf(stderr, "Unable to set transfer align for mic: %s\n", 
	    snd_strerror(ret));
        return ret;
    }

    /* write the parameters to the microphone device */
    ret = snd_pcm_sw_params(handle, swparams);
    if (ret < 0) {
        fprintf(stderr, "Unable to set sw params for mic: %s\n", 
	    snd_strerror(ret));
        return ret;
    }
	
    dump_swparams(handle);
    return 0;
}

static int alsa_set_hwparams()
{
	snd_pcm_hw_params_t *hwp;
	snd_pcm_sw_params_t *swp;
	int dir = 1;
	unsigned period_time;
	snd_pcm_uframes_t buffer_size, period_size;

	snd_pcm_hw_params_alloca(&hwp);
	snd_pcm_sw_params_alloca(&swp);

	// ALSA bug? If we request 44100 Hz, it rounds the value up to 48000...
	alsa_hw.rate--;

	if (alsa_error("hw_params_any", snd_pcm_hw_params_any(alsa_hw.handle, hwp))
	    || alsa_error("hw_params_set_format", snd_pcm_hw_params_set_format(alsa_hw.handle, hwp, alsa_hw.format))
	    || alsa_error("hw_params_set_channels",
			  snd_pcm_hw_params_set_channels(alsa_hw.handle, hwp, alsa_hw.num_channels))
	    || alsa_error("hw_params_set_rate_near",
			  snd_pcm_hw_params_set_rate_near(alsa_hw.handle, hwp, &alsa_hw.rate, &dir))
	    || alsa_error("hw_params_set_access",
			  snd_pcm_hw_params_set_access(alsa_hw.handle, hwp, SND_PCM_ACCESS_RW_INTERLEAVED))
	    || alsa_error("hw_params_set_buffer_time_near",
			  snd_pcm_hw_params_set_buffer_time_near(alsa_hw.handle, hwp, &alsa_hw.buffer_time, 0)))
		return -1;

	/* How often to call our SIGIO handler (~40Hz) */
	period_time = alsa_hw.buffer_time / 4;
	if (alsa_error
	    ("hw_params_set_period_time_near",
	     snd_pcm_hw_params_set_period_time_near(alsa_hw.handle, hwp, &period_time, &dir))
	    || alsa_error("hw_params_get_buffer_size", snd_pcm_hw_params_get_buffer_size(hwp, &buffer_size))
	    || alsa_error("hw_params_get_period_size", snd_pcm_hw_params_get_period_size(hwp, &period_size, 0))
	    || alsa_error("hw_params", snd_pcm_hw_params(alsa_hw.handle, hwp)))
		return -1;

	snd_pcm_sw_params_current(alsa_hw.handle, swp);
	if (alsa_error
	    ("sw_params_set_start_threshold", snd_pcm_sw_params_set_start_threshold(alsa_hw.handle, swp, period_size))
	    || alsa_error("sw_params_set_avail_min", snd_pcm_sw_params_set_avail_min(alsa_hw.handle, swp, period_size))
	    || alsa_error("sw_params", snd_pcm_sw_params(alsa_hw.handle, swp)))
		return -1;

	return 0;
}

/* setup alsa data transfer behavior */
static inline int alsa_set_swparams(ao_alsa_internal *internal)
{
	snd_pcm_sw_params_t   *params;
	int err;

	/* allocate the software parameter structure */
	snd_pcm_sw_params_alloca(&params);

	/* fetch the current software parameters */
	internal->cmd = "snd_pcm_sw_params_current";
	err = snd_pcm_sw_params_current(internal->pcm_handle, params);
	if (err < 0)
		return err;

	/* allow transfers to start when there is one period */
	internal->cmd = "snd_pcm_sw_params_set_start_threshold";
	err = snd_pcm_sw_params_set_start_threshold(internal->pcm_handle,
			params, internal->period_size);
	if (err < 0)
		return err;

	/* require a minimum of one full transfer in the buffer */
	internal->cmd = "snd_pcm_sw_params_set_avail_min";
	err = snd_pcm_sw_params_set_avail_min(internal->pcm_handle, params,
			internal->period_size);
	if (err < 0)
		return err;

	/* do not align transfers */
	internal->cmd = "snd_pcm_sw_params_set_xfer_align";
	err = snd_pcm_sw_params_set_xfer_align(internal->pcm_handle, params, 1);
	if (err < 0)
		return err;

	/* commit the params structure to ALSA */
	internal->cmd = "snd_pcm_sw_params";
	err = snd_pcm_sw_params(internal->pcm_handle, params);
	if (err < 0)
		return err;

	return 1;
}