C++ snd_pcm_hw_params_set_access函数代码示例

static int pcm_open(pcm_handle_t* pcm, const pcm_desc_t* desc)
{
  const snd_pcm_format_t fmt = SND_PCM_FORMAT_S16_LE;
  snd_pcm_stream_t stm;
  int err;

  if (desc->flags & PCM_FLAG_IN) stm = SND_PCM_STREAM_CAPTURE;
  else stm = SND_PCM_STREAM_PLAYBACK;

  err = snd_pcm_open
    (&pcm->pcm, desc->name, stm, SND_PCM_NONBLOCK);
  if (err) PERROR_GOTO(snd_strerror(err), on_error_0);

  err = snd_pcm_hw_params_malloc(&pcm->hw_params);
  if (err) PERROR_GOTO(snd_strerror(err), on_error_1);

  err = snd_pcm_hw_params_any(pcm->pcm, pcm->hw_params);
  if (err) PERROR_GOTO(snd_strerror(err), on_error_2);

  err = snd_pcm_hw_params_set_access
    (pcm->pcm, pcm->hw_params, SND_PCM_ACCESS_RW_INTERLEAVED);
  if (err) PERROR_GOTO(snd_strerror(err), on_error_2);

  err = snd_pcm_hw_params_set_format(pcm->pcm, pcm->hw_params, fmt);
  if (err) PERROR_GOTO(snd_strerror(err), on_error_2);

  err = snd_pcm_hw_params_set_rate
    (pcm->pcm, pcm->hw_params, desc->fsampl, 0);
  if (err) PERROR_GOTO(snd_strerror(err), on_error_2);

  pcm->nchan = desc->nchan;
  pcm->wchan = (size_t)snd_pcm_format_physical_width(fmt) / 8;
  pcm->scale = pcm->nchan * pcm->wchan;

  err = snd_pcm_hw_params_set_channels
    (pcm->pcm, pcm->hw_params, desc->nchan);
  if (err) PERROR_GOTO(snd_strerror(err), on_error_2);
  
  err = snd_pcm_hw_params(pcm->pcm, pcm->hw_params);
  if (err) PERROR_GOTO(snd_strerror(err), on_error_2);

  err = snd_pcm_sw_params_malloc(&pcm->sw_params);
  if (err) PERROR_GOTO(snd_strerror(err), on_error_2);

  err = snd_pcm_sw_params_current(pcm->pcm, pcm->sw_params);
  if (err) PERROR_GOTO(snd_strerror(err), on_error_3);

#if 1
  err = snd_pcm_sw_params_set_avail_min
    (pcm->pcm, pcm->sw_params, 1024);
  if (err) PERROR_GOTO(snd_strerror(err), on_error_3);
#endif

#if 1
  err = snd_pcm_sw_params_set_start_threshold
    (pcm->pcm, pcm->sw_params, 0U);
  if (err) PERROR_GOTO(snd_strerror(err), on_error_3);
#endif

  err = snd_pcm_sw_params(pcm->pcm, pcm->sw_params);
  if (err) PERROR_GOTO(snd_strerror(err), on_error_3);
  
  err = snd_pcm_prepare(pcm->pcm);
  if (err) PERROR_GOTO(snd_strerror(err), on_error_3);

  pcm->rpos = 0;
  pcm->wpos = 0;
  pcm->nsampl = (size_t)desc->fsampl * 10;
  pcm->buf = malloc(pcm->nsampl * pcm->scale);
  if (pcm->buf == NULL) goto on_error_3;

  return 0;

 on_error_3:
  snd_pcm_sw_params_free(pcm->sw_params);
 on_error_2:
  snd_pcm_hw_params_free(pcm->hw_params);
 on_error_1:
  snd_pcm_close(pcm->pcm);
 on_error_0:
  return -1;
  
}

static pj_status_t open_capture (struct alsa_stream* stream,
			         const pjmedia_aud_param *param)
{
    snd_pcm_hw_params_t* params;
    snd_pcm_format_t format;
    int result;
    unsigned int rate;
    snd_pcm_uframes_t tmp_buf_size;
    snd_pcm_uframes_t tmp_period_size;

    if (param->rec_id < 0 || param->rec_id >= stream->af->dev_cnt)
	return PJMEDIA_EAUD_INVDEV;

    /* Open PCM for capture */
    PJ_LOG (5,(THIS_FILE, "open_capture: Open capture device '%s'",
	       stream->af->devs[param->rec_id].name));
    result = snd_pcm_open (&stream->ca_pcm,
		            stream->af->devs[param->rec_id].name,
			   SND_PCM_STREAM_CAPTURE,
			   0);
    if (result < 0)
	return PJMEDIA_EAUD_SYSERR;

    /* Allocate a hardware parameters object. */
    snd_pcm_hw_params_alloca (&params);

    /* Fill it in with default values. */
    snd_pcm_hw_params_any (stream->ca_pcm, params);

    /* Set interleaved mode */
    snd_pcm_hw_params_set_access (stream->ca_pcm, params,
				  SND_PCM_ACCESS_RW_INTERLEAVED);

    /* Set format */
    switch (param->bits_per_sample) {
    case 8:
	TRACE_((THIS_FILE, "open_capture: set format SND_PCM_FORMAT_S8"));
	format = SND_PCM_FORMAT_S8;
	break;
    case 16:
	TRACE_((THIS_FILE, "open_capture: set format SND_PCM_FORMAT_S16_LE"));
	format = SND_PCM_FORMAT_S16_LE;
	break;
    case 24:
	TRACE_((THIS_FILE, "open_capture: set format SND_PCM_FORMAT_S24_LE"));
	format = SND_PCM_FORMAT_S24_LE;
	break;
    case 32:
	TRACE_((THIS_FILE, "open_capture: set format SND_PCM_FORMAT_S32_LE"));
	format = SND_PCM_FORMAT_S32_LE;
	break;
    default:
	TRACE_((THIS_FILE, "open_capture: set format SND_PCM_FORMAT_S16_LE"));
	format = SND_PCM_FORMAT_S16_LE;
	break;
    }
    snd_pcm_hw_params_set_format (stream->ca_pcm, params, format);

    /* Set number of channels */
    TRACE_((THIS_FILE, "open_capture: set channels: %d",
	    param->channel_count));
    snd_pcm_hw_params_set_channels (stream->ca_pcm, params,
				    param->channel_count);

    /* Set clock rate */
    rate = param->clock_rate;
    TRACE_((THIS_FILE, "open_capture: set clock rate: %d", rate));
    snd_pcm_hw_params_set_rate_near (stream->ca_pcm, params, &rate, NULL);
    TRACE_((THIS_FILE, "open_capture: clock rate set to: %d", rate));

    /* Set period size to samples_per_frame frames. */
    stream->ca_frames = (snd_pcm_uframes_t) param->samples_per_frame /
					    param->channel_count;
    TRACE_((THIS_FILE, "open_capture: set period size: %d",
	    stream->ca_frames));
    tmp_period_size = stream->ca_frames;
    snd_pcm_hw_params_set_period_size_near (stream->ca_pcm, params,
					    &tmp_period_size, NULL);
    TRACE_((THIS_FILE, "open_capture: period size set to: %d",
	    tmp_period_size));

    /* Set the sound device buffer size and latency */
    if (param->flags & PJMEDIA_AUD_DEV_CAP_INPUT_LATENCY)
	tmp_buf_size = (rate / 1000) * param->input_latency_ms;
    else
	tmp_buf_size = (rate / 1000) * PJMEDIA_SND_DEFAULT_REC_LATENCY;
    snd_pcm_hw_params_set_buffer_size_near (stream->ca_pcm, params,
					    &tmp_buf_size);
    stream->param.input_latency_ms = tmp_buf_size / (rate / 1000);

    /* Set our buffer */
    stream->ca_buf_size = stream->ca_frames * param->channel_count *
			  (param->bits_per_sample/8);
    stream->ca_buf = (char*) pj_pool_alloc (stream->pool, stream->ca_buf_size);

    TRACE_((THIS_FILE, "open_capture: buffer size set to: %d",
	    (int)tmp_buf_size));
    TRACE_((THIS_FILE, "open_capture: capture_latency set to: %d ms",
	    (int)stream->param.input_latency_ms));

//.........这里部分代码省略.........

static int
set_hwparams (GstAlsaSink * alsa)
{
  guint rrate;
  gint err;
  snd_pcm_hw_params_t *params;
  guint period_time, buffer_time;

  snd_pcm_hw_params_malloc (&params);

  GST_DEBUG_OBJECT (alsa, "Negotiating to %d channels @ %d Hz (format = %s) "
      "SPDIF (%d)", alsa->channels, alsa->rate,
      snd_pcm_format_name (alsa->format), alsa->iec958);

  /* start with requested values, if we cannot configure alsa for those values,
   * we set these values to -1, which will leave the default alsa values */
  buffer_time = alsa->buffer_time;
  period_time = alsa->period_time;

retry:
  /* choose all parameters */
  CHECK (snd_pcm_hw_params_any (alsa->handle, params), no_config);
  /* set the interleaved read/write format */
  CHECK (snd_pcm_hw_params_set_access (alsa->handle, params, alsa->access),
      wrong_access);
  /* set the sample format */
  if (alsa->iec958) {
    /* Try to use big endian first else fallback to le and swap bytes */
    if (snd_pcm_hw_params_set_format (alsa->handle, params, alsa->format) < 0) {
      alsa->format = SND_PCM_FORMAT_S16_LE;
      alsa->need_swap = TRUE;
      GST_DEBUG_OBJECT (alsa, "falling back to little endian with swapping");
    } else {
      alsa->need_swap = FALSE;
    }
  }
  CHECK (snd_pcm_hw_params_set_format (alsa->handle, params, alsa->format),
      no_sample_format);
  /* set the count of channels */
  CHECK (snd_pcm_hw_params_set_channels (alsa->handle, params, alsa->channels),
      no_channels);
  /* set the stream rate */
  rrate = alsa->rate;
  CHECK (snd_pcm_hw_params_set_rate_near (alsa->handle, params, &rrate, NULL),
      no_rate);
  if (rrate != alsa->rate)
    goto rate_match;

#ifndef GST_DISABLE_GST_DEBUG
  /* get and dump some limits */
  {
    guint min, max;

    snd_pcm_hw_params_get_buffer_time_min (params, &min, NULL);
    snd_pcm_hw_params_get_buffer_time_max (params, &max, NULL);

    GST_DEBUG_OBJECT (alsa, "buffer time %u, min %u, max %u",
        alsa->buffer_time, min, max);

    snd_pcm_hw_params_get_period_time_min (params, &min, NULL);
    snd_pcm_hw_params_get_period_time_max (params, &max, NULL);

    GST_DEBUG_OBJECT (alsa, "period time %u, min %u, max %u",
        alsa->period_time, min, max);

    snd_pcm_hw_params_get_periods_min (params, &min, NULL);
    snd_pcm_hw_params_get_periods_max (params, &max, NULL);

    GST_DEBUG_OBJECT (alsa, "periods min %u, max %u", min, max);
  }
#endif

  /* now try to configure the buffer time and period time, if one
   * of those fail, we fall back to the defaults and emit a warning. */
  if (buffer_time != -1 && !alsa->iec958) {
    /* set the buffer time */
    if ((err = snd_pcm_hw_params_set_buffer_time_near (alsa->handle, params,
                &buffer_time, NULL)) < 0) {
      GST_ELEMENT_WARNING (alsa, RESOURCE, SETTINGS, (NULL),
          ("Unable to set buffer time %i for playback: %s",
              buffer_time, snd_strerror (err)));
      /* disable buffer_time the next round */
      buffer_time = -1;
      goto retry;
    }
    GST_DEBUG_OBJECT (alsa, "buffer time %u", buffer_time);
  }
  if (period_time != -1 && !alsa->iec958) {
    /* set the period time */
    if ((err = snd_pcm_hw_params_set_period_time_near (alsa->handle, params,
                &period_time, NULL)) < 0) {
      GST_ELEMENT_WARNING (alsa, RESOURCE, SETTINGS, (NULL),
          ("Unable to set period time %i for playback: %s",
              period_time, snd_strerror (err)));
      /* disable period_time the next round */
      period_time = -1;
      goto retry;
    }
    GST_DEBUG_OBJECT (alsa, "period time %u", period_time);
  }
//.........这里部分代码省略.........

int main()
{
	int fp,ff;
  unsigned int pcm, tmp, dir;
  int buff_size;
	char filename[20] = "123.wav";
  long loops;
  int rc;
  int size;
  snd_pcm_t *handle;
  snd_pcm_hw_params_t *params;
  unsigned int val;
  
  snd_pcm_uframes_t frames;
  char *buff,*ipaddress;
  int rate, channels, seconds;
//printf("aaa\n");
  /* Open PCM device for recording (capture). */
  rc = snd_pcm_open(&handle, "default", SND_PCM_STREAM_CAPTURE, 0);

  if (rc < 0) 
  {
    fprintf(stderr,"unable to open pcm device: %s\n",   snd_strerror(rc));
    exit(1);
  }
  /* Allocate a hardware parameters object. */
  snd_pcm_hw_params_alloca(&params);

  /* Fill it in with default values. */
  snd_pcm_hw_params_any(handle, params);

  /* Set the desired hardware parameters. */

  /* Interleaved mode */
  snd_pcm_hw_params_set_access(handle, params,  SND_PCM_ACCESS_RW_INTERLEAVED);

  /* Signed 16-bit little-endian format */
  snd_pcm_hw_params_set_format(handle, params,SND_PCM_FORMAT_U8);

  /* Two channels (stereo) */
  snd_pcm_hw_params_set_channels(handle, params, 1);

  /* 44100 bits/second sampling rate (CD quality) */
  val = 8000;
  
  snd_pcm_hw_params_set_rate_near(handle, params,  &val, &dir);

  /* Set period size to 32 frames. */
  frames = 32;
  snd_pcm_hw_params_set_period_size_near(handle,params, &frames, &dir);

  /* Write the parameters to the driver */
  rc = snd_pcm_hw_params(handle, params);
  if (rc < 0) 
  {
    fprintf(stderr,"unable to set hw parameters: %s\n", snd_strerror(rc));
    exit(1);
  }

  /* Use a buff large enough to hold one period */

  snd_pcm_hw_params_get_period_size(params,  &frames, &dir);
  size = frames * 4; /* 2 bytes/sample, 2 channels */
  buff = (char *) malloc(size);

  /* We want to loop for 5 seconds */

  snd_pcm_hw_params_get_period_time(params, &val, &dir);
  loops = 50000000 / val;

  fp=open("123.wav",O_WRONLY);
  ipaddress = malloc(sizeof(char) * 4);

  /*printf("\n\tEnter ip : ");
  scanf("%s",ipaddress);*/

//  printf("sending data\n");
  
  for (loops=500000 / val;loops > 0;loops--) 
  {
		bzero(buff,sizeof(buff));
		rc = snd_pcm_readi(handle, buff, frames);
		write(fp,buff,128);
		fun(buff,128,filename);
	
	//	fucntion1(ipaddress,buff,size);
		
		if (rc == -EPIPE) 
		{
		  /* EPIPE means overrun */
		  fprintf(stderr, "overrun occurred\n");
		  snd_pcm_prepare(handle);
		} 
		else if (rc < 0) 
		{
		  fprintf(stderr,"error from read: %s\n",  snd_strerror(rc));
		} 
		else if (rc != (int)frames) 
		{
		  fprintf(stderr, "short read, read %d frames\n", rc);
//.........这里部分代码省略.........

bool QAudioInputPrivate::open()
{
#ifdef DEBUG_AUDIO
    QTime now(QTime::currentTime());
    qDebug()<<now.second()<<"s "<<now.msec()<<"ms :open()";
#endif
    clockStamp.restart();
    timeStamp.restart();
    elapsedTimeOffset = 0;

    int dir;
    int err = 0;
    int count=0;
    unsigned int freakuency=settings.frequency();

    if (!settings.isValid()) {
        qWarning("QAudioOutput: open error, invalid format.");
    } else if (settings.sampleRate() <= 0) {
        qWarning("QAudioOutput: open error, invalid sample rate (%d).",
                 settings.sampleRate());
    } else {
        err = -1;
    }

    if (err == 0) {
        errorState = QAudio::OpenError;
        deviceState = QAudio::StoppedState;
        emit errorChanged(errorState);
        return false;
    }


    QString dev = QString(QLatin1String(m_device.constData()));
    QList<QByteArray> devices = QAudioDeviceInfoInternal::availableDevices(QAudio::AudioInput);
    if(dev.compare(QLatin1String("default")) == 0) {
#if(SND_LIB_MAJOR == 1 && SND_LIB_MINOR == 0 && SND_LIB_SUBMINOR >= 14)
        if (devices.size() > 0)
            dev = QLatin1String(devices.first());
        else
            return false;
#else
        dev = QLatin1String("hw:0,0");
#endif
    } else {
#if(SND_LIB_MAJOR == 1 && SND_LIB_MINOR == 0 && SND_LIB_SUBMINOR >= 14)
        dev = QLatin1String(m_device);
#else
        int idx = 0;
        char *name;

        QString shortName = QLatin1String(m_device.mid(m_device.indexOf('=',0)+1).constData());

        while(snd_card_get_name(idx,&name) == 0) {
            if(qstrncmp(shortName.toLocal8Bit().constData(),name,shortName.length()) == 0)
                break;
            idx++;
        }
        dev = QString(QLatin1String("hw:%1,0")).arg(idx);
#endif
    }

    // Step 1: try and open the device
    while((count < 5) && (err < 0)) {
        err=snd_pcm_open(&handle,dev.toLocal8Bit().constData(),SND_PCM_STREAM_CAPTURE,0);
        if(err < 0)
            count++;
    }
    if (( err < 0)||(handle == 0)) {
        errorState = QAudio::OpenError;
        deviceState = QAudio::StoppedState;
        emit stateChanged(deviceState);
        return false;
    }
    snd_pcm_nonblock( handle, 0 );

    // Step 2: Set the desired HW parameters.
    snd_pcm_hw_params_alloca( &hwparams );

    bool fatal = false;
    QString errMessage;
    unsigned int chunks = 8;

    err = snd_pcm_hw_params_any( handle, hwparams );
    if ( err < 0 ) {
        fatal = true;
        errMessage = QString::fromLatin1("QAudioInput: snd_pcm_hw_params_any: err = %1").arg(err);
    }
    if ( !fatal ) {
        err = snd_pcm_hw_params_set_rate_resample( handle, hwparams, 1 );
        if ( err < 0 ) {
            fatal = true;
            errMessage = QString::fromLatin1("QAudioInput: snd_pcm_hw_params_set_rate_resample: err = %1").arg(err);
        }
    }
    if ( !fatal ) {
        err = snd_pcm_hw_params_set_access( handle, hwparams, access );
        if ( err < 0 ) {
            fatal = true;
            errMessage = QString::fromLatin1("QAudioInput: snd_pcm_hw_params_set_access: err = %1").arg(err);
        }
//.........这里部分代码省略.........

static int pcm_open(struct alsa_pcm *alsa, const char *device_name,
                    snd_pcm_stream_t stream, int rate, int buffer_time)
{
    int r, dir;
    unsigned int p;
    size_t bytes;
    snd_pcm_hw_params_t *hw_params;
    
    r = snd_pcm_open(&alsa->pcm, device_name, stream, SND_PCM_NONBLOCK);
    if (!chk("open", r))
        return -1;

    snd_pcm_hw_params_alloca(&hw_params);

    r = snd_pcm_hw_params_any(alsa->pcm, hw_params);
    if (!chk("hw_params_any", r))
        return -1;
    
    r = snd_pcm_hw_params_set_access(alsa->pcm, hw_params,
                                     SND_PCM_ACCESS_RW_INTERLEAVED);
    if (!chk("hw_params_set_access", r))
        return -1;
    
    r = snd_pcm_hw_params_set_format(alsa->pcm, hw_params, SND_PCM_FORMAT_S16);
    if (!chk("hw_params_set_format", r)) {
        fprintf(stderr, "16-bit signed format is not available. "
                "You may need to use a 'plughw' device.\n");
        return -1;
    }

    r = snd_pcm_hw_params_set_rate(alsa->pcm, hw_params, rate, 0);
    if (!chk("hw_params_set_rate", r )) {
        fprintf(stderr, "%dHz sample rate not available. You may need to use "
                "a 'plughw' device.\n", rate);
        return -1;
    }
    alsa->rate = rate;

    r = snd_pcm_hw_params_set_channels(alsa->pcm, hw_params, DEVICE_CHANNELS);
    if (!chk("hw_params_set_channels", r)) {
        fprintf(stderr, "%d channel audio not available on this device.\n",
                DEVICE_CHANNELS);
        return -1;
    }

    p = buffer_time * 1000; /* microseconds */
    dir = -1;
    r = snd_pcm_hw_params_set_buffer_time_near(alsa->pcm, hw_params, &p, &dir);
    if (!chk("hw_params_set_buffer_time_near", r)) {
        fprintf(stderr, "Buffer of %dms may be too small for this hardware.\n",
                buffer_time);
        return -1;
    }

    p = 2; /* double buffering */
    dir = 1;
    r = snd_pcm_hw_params_set_periods_min(alsa->pcm, hw_params, &p, &dir);
    if (!chk("hw_params_set_periods_min", r)) {
        fprintf(stderr, "Buffer of %dms may be too small for this hardware.\n",
                buffer_time);
        return -1;
    }

    r = snd_pcm_hw_params(alsa->pcm, hw_params);
    if (!chk("hw_params", r))
        return -1;
    
    r = snd_pcm_hw_params_get_period_size(hw_params, &alsa->period, &dir);
    if (!chk("get_period_size", r))
        return -1;

    bytes = alsa->period * DEVICE_CHANNELS * sizeof(signed short);
    alsa->buf = malloc(bytes);
    if (!alsa->buf) {
        perror("malloc");
        return -1;
    }

    /* snd_pcm_readi() returns uninitialised memory on first call,
     * possibly caused by premature POLLIN. Keep valgrind happy. */

    memset(alsa->buf, 0, bytes);

    return 0;
}

int main()
{
    long loops;
    int rc;
    int size;
    snd_pcm_t *rec_handle;
    snd_pcm_hw_params_t *rec_params;
    unsigned int val;
    int dir;
    snd_pcm_uframes_t frames;
    char *buffer;
    WAVEHDR wavheader;
    int total_len = 0;
    FILE *fp_rec = fopen("rec.wav", "wb");
    if(fp_rec==NULL)
    {
        return 0;
    }
    wav_start_write(fp_rec, &wavheader);
    /* Open PCM device for recording (capture). */
    rc = snd_pcm_open(&rec_handle, "default",
                      SND_PCM_STREAM_CAPTURE, 0);
    if (rc < 0) {
        fprintf(stderr,
                "unable to open pcm device: %s\n",
                snd_strerror(rc));
        exit(1);
    }

    /* Allocate a hardware parameters object. */
    snd_pcm_hw_params_alloca(&rec_params);

    /* Fill it in with default values. */
    snd_pcm_hw_params_any(rec_handle, rec_params);

    /* Set the desired hardware parameters. */

    /* Interleaved mode */
    snd_pcm_hw_params_set_access(rec_handle, rec_params,
                                 SND_PCM_ACCESS_RW_INTERLEAVED);

    /* Signed 16-bit little-endian format */
    snd_pcm_hw_params_set_format(rec_handle, rec_params,
                                 SND_PCM_FORMAT_S16_LE);

    /* Two channels (stereo) */
    snd_pcm_hw_params_set_channels(rec_handle, rec_params, 1);

    /* 44100 bits/second sampling rate (CD quality) */
    val = 8000;
    snd_pcm_hw_params_set_rate_near(rec_handle, rec_params,
                                    &val, &dir);

    /* Set period size to 32 frames. */
    frames = 32;
    snd_pcm_hw_params_set_period_size_near(rec_handle,
                                           rec_params, &frames, &dir);

    /* Write the parameters to the driver */
    rc = snd_pcm_hw_params(rec_handle, rec_params);
    if (rc < 0)
    {
        fprintf(stderr,
                "unable to set hw parameters: %s\n",
                snd_strerror(rc));
        exit(1);
    }

    /* Use a buffer large enough to hold one period */
    snd_pcm_hw_params_get_period_size(rec_params,  &frames, &dir);
    size = frames * 2; /* 2 bytes/sample, 2 channels */
    buffer = (char *) malloc(size);

    /* We want to loop for 5 seconds */
    snd_pcm_hw_params_get_period_time(rec_params, &val, &dir);
    loops = 2000;

    while (loops-- > 0)
    {
        rc = snd_pcm_readi(rec_handle, buffer, frames);
        if (rc == -EPIPE)
        {
            /* EPIPE means overrun */
            fprintf(stderr, "overrun occurred\n");
            snd_pcm_prepare(rec_handle);
        }
        else if (rc < 0)
        {
            fprintf(stderr, "error from read: %s\n", snd_strerror(rc));
        }
        else if (rc != (int)frames)
        {
            fprintf(stderr, "short read, read %d frames\n", rc);
        }
        rc = fwrite(buffer, 1, size, fp_rec);
        total_len += size;
        printf("#\n");
        if (rc != size)
            fprintf(stderr,"short write: wrote %d bytes\n", rc);
    }
//.........这里部分代码省略.........

//.........这里部分代码省略.........
        settings_current.sound = 0;
        ui_error( UI_ERROR_ERROR,
                  "couldn't open sound device 'default' and 'plughw:0,0' check ALSA configuration."
                  );
	init_running = 0;
        return 1;
      } else {
        if( first_init )
          fprintf( stderr,
                    "Couldn't open sound device 'default', using 'plughw:0,0' check ALSA configuration.\n"
                    );
      }
    }
    settings_current.sound = 0;
    ui_error( UI_ERROR_ERROR, "couldn't open sound device '%s'.", pcm_name );
    init_running = 0;
    return 1;
  }

/* Allocate the snd_pcm_hw_params_t structure on the stack. */
  snd_pcm_hw_params_alloca( &hw_params );

/* Init hw_params with full configuration space */
  if( snd_pcm_hw_params_any( pcm_handle, hw_params ) < 0 ) {
    settings_current.sound = 0;
    ui_error( UI_ERROR_ERROR,
              "couldn't get configuration space on sound device '%s'.",
              pcm_name );
    snd_pcm_close( pcm_handle );
    init_running = 0;
    return 1;
  }

  if( snd_pcm_hw_params_set_access( pcm_handle, hw_params,
                                    SND_PCM_ACCESS_RW_INTERLEAVED ) < 0) {
    settings_current.sound = 0;
    ui_error( UI_ERROR_ERROR, "couldn't set access interleaved on '%s'.",
              pcm_name );
    snd_pcm_close( pcm_handle );
    init_running = 0;
    return 1;
  }
  
    /* Set sample format */
  if( snd_pcm_hw_params_set_format( pcm_handle, hw_params, 
#if defined WORDS_BIGENDIAN
				    SND_PCM_FORMAT_S16_BE
#else
				    SND_PCM_FORMAT_S16_LE
#endif
						    ) < 0 ) {
    settings_current.sound = 0;
    ui_error( UI_ERROR_ERROR, "couldn't set format on '%s'.", pcm_name );
    snd_pcm_close( pcm_handle );
    init_running = 0;
    return 1;
  }

  ch = *stereoptr ? 2 : 1;

  if( snd_pcm_hw_params_set_channels( pcm_handle, hw_params, ch )
	    < 0 ) {
    fprintf( stderr, "Couldn't set %s to '%s'.\n", pcm_name,
    		    (*stereoptr ? "stereo" : "mono") );
    ch = *stereoptr ? 1 : 2;		/* try with opposite */
    if( snd_pcm_hw_params_set_channels( pcm_handle, hw_params, ch )

bool QAudioInputPrivate::open( QObject *input )
{
    // Open the Alsa capture device.
    bool    rc = true;
    int     err;

    unsigned int        freakuency = frequency;

    if ((err = snd_pcm_open(&handle,
                             m_device.constData(), //"plughw:0,0"
                             SND_PCM_STREAM_CAPTURE,
                                 0/*SND_PCM_ASYNC*/)) < 0) {

        qWarning( "QAudioInput: snd_pcm_open: error %d", err);

        rc = false;
    }
    else {
        snd_pcm_hw_params_t *hwparams;

        // We want non-blocking mode.
        snd_pcm_nonblock(handle, 1);

        // Set the desired parameters.
        snd_pcm_hw_params_alloca(&hwparams);

        err = snd_pcm_hw_params_any(handle, hwparams);
        if ( err < 0 ) {
            qWarning( "QAudioInput: snd_pcm_hw_params_any: err %d", err);
        }

        err = snd_pcm_hw_params_set_access(handle, hwparams,
                                           access);
        if ( err < 0 ) {
            qWarning( "QAudioInput: snd_pcm_hw_params_set_access: err %d",err);
        }

        err = snd_pcm_hw_params_set_format(handle, hwparams,format);
        if ( err < 0 ) {
            qWarning( "QAudioInput: snd_pcm_hw_params_set_format: err %d",err);
        }

        err = snd_pcm_hw_params_set_channels(handle,hwparams,(unsigned int)channels);
        if ( err < 0 ) {
            qWarning( "QAudioInput: snd_pcm_hw_params_set_channels: err %d",err);
        }

        err = snd_pcm_hw_params_set_rate_near(handle, hwparams, &freakuency, 0);
        if ( err < 0 ) {
            qWarning( "QAudioInput: snd_pcm_hw_params_set_rate_near: err %d",err);
        }
        if(freakuency > 1.05 * frequency || freakuency < 0.95 * frequency) {
            qWarning("QAudioInput: warning, sample rate %i not supported by the hardware, using %u", frequency, freakuency);
        }

        if ( samplesPerBlock != -1 ) {
            // Set buffer and period sizes based on the supplied block size.
            sample_size = (snd_pcm_uframes_t)( samplesPerBlock * channels / 8 );
            err = snd_pcm_hw_params_set_rate_near(handle, hwparams, &freakuency, 0);
            if ( err < 0 ) {
                qWarning( "QAudioInput: snd_pcm_hw_params_set_rate_near: err %d",err);
            }
            if(freakuency > 1.05 * frequency || freakuency < 0.95 * frequency) {
                qWarning( "QAudioInput: warning, sample rate %i not supported by the hardware, using %u", frequency, freakuency);
            }

            err = snd_pcm_hw_params_set_buffer_time_near(handle, hwparams, &buffer_time, 0);
            if ( err < 0 ) {
                qWarning( "QAudioInput: snd_pcm_hw_params_set_buffer_time_near: err %d",err);
            }
            period_time = 1000000 * 256 / frequency;
            err = snd_pcm_hw_params_set_period_time_near(handle, hwparams, &period_time, 0);
            if ( err < 0 ) {
                qWarning( "QAudioInput: snd_pcm_hw_params_set_period_time_near: err %d",err);
            }
        } else {
            // Use the largest buffer and period sizes we can.
            err = snd_pcm_hw_params_set_buffer_time_near(handle, hwparams, &buffer_time, 0);
            if ( err < 0 ) {
                qWarning( "QAudioInput: snd_pcm_hw_params_set_buffer_time_near: err %d",err);
            }
            period_time = 1000000 * 256 / frequency;
            err = snd_pcm_hw_params_set_period_time_near(handle, hwparams, &period_time, 0);
            if ( err < 0 ) {
                qWarning( "QAudioInput: snd_pcm_hw_params_set_period_time_near: err %d",err);
            }
       }

        err = snd_pcm_hw_params(handle, hwparams);
        if ( err < 0 ) {
            qWarning( "QAudioInput: snd_pcm_hw_params: err %d",err);
        }

        int                  dir;
        unsigned int         vval, vval2;
        snd_pcm_access_t     aval;
        snd_pcm_format_t     fval;
        snd_pcm_subformat_t  sval;

        qLog(QAudioInput) << "PCM handle name = " << snd_pcm_name(handle);
//.........这里部分代码省略.........

	main (int argc, char *argv[])
	{
		int i;
		int err;
		short buf[128];
		snd_pcm_t *capture_handle;
		snd_pcm_hw_params_t *hw_params;
	
		if ((err = snd_pcm_open (&capture_handle, argv[1], SND_PCM_STREAM_CAPTURE, 0)) < 0) {
			fprintf (stderr, "cannot open audio device %s (%s)\n", 
				 argv[1],
				 snd_strerror (err));
			exit (1);
		}
		   
		if ((err = snd_pcm_hw_params_malloc (&hw_params)) < 0) {
			fprintf (stderr, "cannot allocate hardware parameter structure (%s)\n",
				 snd_strerror (err));
			exit (1);
		}
				 
		if ((err = snd_pcm_hw_params_any (capture_handle, hw_params)) < 0) {
			fprintf (stderr, "cannot initialize hardware parameter structure (%s)\n",
				 snd_strerror (err));
			exit (1);
		}
	
		if ((err = snd_pcm_hw_params_set_access (capture_handle, hw_params, SND_PCM_ACCESS_RW_INTERLEAVED)) < 0) {
			fprintf (stderr, "cannot set access type (%s)\n",
				 snd_strerror (err));
			exit (1);
		}
	
		if ((err = snd_pcm_hw_params_set_format (capture_handle, hw_params, SND_PCM_FORMAT_S16_LE)) < 0) {
			fprintf (stderr, "cannot set sample format (%s)\n",
				 snd_strerror (err));
			exit (1);
		}
	
		if ((err = snd_pcm_hw_params_set_rate_near (capture_handle, hw_params, 44100, 0)) < 0) {
			fprintf (stderr, "cannot set sample rate (%s)\n",
				 snd_strerror (err));
			exit (1);
		}
	
		if ((err = snd_pcm_hw_params_set_channels (capture_handle, hw_params, 2)) < 0) {
			fprintf (stderr, "cannot set channel count (%s)\n",
				 snd_strerror (err));
			exit (1);
		}
	
		if ((err = snd_pcm_hw_params (capture_handle, hw_params)) < 0) {
			fprintf (stderr, "cannot set parameters (%s)\n",
				 snd_strerror (err));
			exit (1);
		}
	
		snd_pcm_hw_params_free (hw_params);
	
		if ((err = snd_pcm_prepare (capture_handle)) < 0) {
			fprintf (stderr, "cannot prepare audio interface for use (%s)\n",
				 snd_strerror (err));
			exit (1);
		}
	
		for (i = 0; i < 10; ++i) {
			if ((err = snd_pcm_readi (capture_handle, buf, 128)) != 128) {
				fprintf (stderr, "read from audio interface failed (%s)\n",
					 snd_strerror (err));
				exit (1);
			}
		}
	
		snd_pcm_close (capture_handle);
		exit (0);
	}

void* play_thread(void *argv)
{
    char *__file_name = argv;
    struct WAVE *_wave;

#ifdef SOLO
    _wave = (struct WAVE*)malloc(sizeof(struct WAVE));
    memset(&_wave, 0, sizeof(struct _wave));
    if(!wave_read_file(argv, &_wave )){
	goto ERR;
    }
#else
    if(!list_count){
	fprintf(stderr,"[PLAY]: Not such wav sound file.\nPlease call \'play_read_filelist(DIR_PATH)\'\n");
	exit(1);
    }
    for(_wave=head;;_wave=_wave->next){
	if(!strcmp(_wave->file_name, __file_name))break;
	if(head->prev == _wave){
	    fprintf(stderr,"[PLAY]: Invalid file_name...\n");
	    return NULL;
	}
    }
#endif
    if(DISP)
	fprintf(stderr,"[PLAY]: Player will be playing \"%s\".\n",__file_name);

    snd_pcm_t *handle;                  // handle for sound_device
    snd_pcm_hw_params_t *params;        // params for sound_device
    int result_func = 0;                // result for function return
    unsigned int sampling_rate = _wave->rate;   // sampling rate
    int dir;    // sub unit direction
    snd_pcm_uframes_t frames = 32;        // size of frame
    unsigned int buffer_size;                   // buffer_size for frame
    int16_t *frameBuffer=NULL;                       // buffer for frame
    unsigned int approximate_period;                     // period[us]

    {// open the pcm device
	// open pcm device
	result_func = snd_pcm_open(
		&handle, "default", SND_PCM_STREAM_PLAYBACK, 0);
	if ( result_func < 0 )
	{
	    fprintf(stderr,
		    "[PLAY]: unable to open pcm device :%s\n",
		    snd_strerror(result_func));
	    goto ERR;
	}
    }

    {// set parameter to device
	// allocate device params
	snd_pcm_hw_params_alloca(&params);
	// get default param
	snd_pcm_hw_params_any(handle, params);
	// set parameter Interleaved mode
	snd_pcm_hw_params_set_access(handle, params,
		SND_PCM_ACCESS_RW_INTERLEAVED);
	// set format parameter : monoral 1ch 16bit LittleEndian
	snd_pcm_hw_params_set_format(handle, params,
		SND_PCM_FORMAT_S16_LE);
	// set output_device parameter stereo 2ch
	snd_pcm_hw_params_set_channels(handle, params, _wave->channel);
	// approximates to a specified sampling rate
	// pcm	PCM handle
	// params	Configuration space
	// val	approximate target rate / returned approximate set rate
	// dir	Sub unit direction 
	snd_pcm_hw_params_set_rate_near(
		handle, params, &sampling_rate, &dir);
	// set parameter size of frame
	snd_pcm_hw_params_set_period_size_near(handle, params, &frames, &dir);
	// set parameter to hardware_device
	result_func = snd_pcm_hw_params(handle, params);

	// err check
	if (result_func < 0) {
	    fprintf(stderr, "[PLAY]: unable to set hw parameters: %s\n",
		    snd_strerror(result_func));
	    goto ERR;
	}

	// get bufferSize / frame
	snd_pcm_hw_params_get_period_size(params, &frames, &dir);
	// calculate buffer_size
	buffer_size = frames * 2; /*????????? 48000,monoral ver */
	// allocate buffer
	frameBuffer = (int16_t *)malloc(buffer_size);
	memset(frameBuffer, 0, sizeof(*frameBuffer));

	// get playback period
	// params	Configuration space
	// val	Returned approximate period duration in us
	// dir	Sub unit direction 
	snd_pcm_hw_params_get_period_time(params, &approximate_period, &dir);
    }


    { // playback process
	// playback time
//.........这里部分代码省略.........

bool
AlsaSource::SetupHW ()
{
	bool result = false;
	bool rw_available = false;
	bool mmap_available = false;
#if DEBUG
	bool debug = debug_flags & RUNTIME_DEBUG_AUDIO;
#else
	bool debug = false;
#endif
	
	snd_pcm_hw_params_t *params = NULL;
	snd_output_t *output = NULL;
	guint32 buffer_time = 100000; // request 0.1 seconds of buffer time.
	int err = 0;
	int dir = 0;
	unsigned int rate = GetSampleRate ();
	unsigned int actual_rate = rate;
	guint32 channels = GetChannels ();

	if (debug) {
		err = snd_output_stdio_attach (&output, stdout, 0);
		if (err < 0)
			LOG_AUDIO ("AlsaSource::SetupHW (): Could not create alsa output: %s\n", snd_strerror (err));
	}

	err = snd_pcm_hw_params_malloc (&params);
	if (err < 0) {
		LOG_AUDIO ("AlsaSource::SetupHW (): Audio HW setup failed (malloc): %s\n", snd_strerror (err));
		return false;
	}

	// choose all parameters
	err = snd_pcm_hw_params_any (pcm, params);
	if (err < 0) {
		LOG_AUDIO ("AlsaSource::SetupHW (): Audio HW setup failed (no configurations available): %s\n", snd_strerror (err));
		goto cleanup;
	}
	
	if (debug && output != NULL) {
		LOG_AUDIO ("AlsaSource::SetupHW (): hw configurations:\n");
		snd_pcm_hw_params_dump (params, output);
	}
	
	// enable software resampling
	err = snd_pcm_hw_params_set_rate_resample (pcm, params, 1);
	if (err < 0) {
		LOG_AUDIO ("AlsaSource::SetupHW (): Audio HW setup failed (could not enable resampling): %s\n", snd_strerror (err));
		goto cleanup;
	}
	
	// test for available transfer modes
	if (!(moonlight_flags & RUNTIME_INIT_AUDIO_ALSA_MMAP)) {
		err = snd_pcm_hw_params_test_access (pcm, params, SND_PCM_ACCESS_RW_INTERLEAVED);
		if (err < 0) {
			LOG_AUDIO ("AlsaSource::SetupHW (): Audio HW setup: RW access mode not supported (%s).\n", snd_strerror (err));			
		} else {
			rw_available = true;
		}
	}
	if (!(moonlight_flags & RUNTIME_INIT_AUDIO_ALSA_RW)) {
		err = snd_pcm_hw_params_test_access (pcm, params, SND_PCM_ACCESS_MMAP_INTERLEAVED);
		if (err < 0) {
			LOG_AUDIO ("AlsaSource::SetupHW (): Audio HW setup: MMAP access mode not supported (%s).\n", snd_strerror (err));
		} else {
			mmap_available = true;
		}
	}
	if (mmap_available) {
		mmap = true;
	} else if (rw_available) {
		mmap = false;
	} else {
		LOG_AUDIO ("AlsaSource::SetupHW (): Audio HW setup failed, no available access mode\n");
		goto cleanup;
	}

	LOG_AUDIO ("AlsaSource::SetupHW (): Audio HW setup: using %s access mode.\n", mmap ? "MMAP" : "RW");

	// set transfer mode (mmap or rw in our case)
	err = snd_pcm_hw_params_set_access (pcm, params, mmap ? SND_PCM_ACCESS_MMAP_INTERLEAVED : SND_PCM_ACCESS_RW_INTERLEAVED);
	if (err < 0) {
		LOG_AUDIO ("AlsaSource::SetupHW (): Audio HW setup failed (access type not available for playback): %s\n", snd_strerror (err));
		goto cleanup;
	}

	// set audio format
	switch (GetInputBytesPerSample ()) {
	case 1: // 8 bit audio
		err = snd_pcm_hw_params_set_format (pcm, params, SND_PCM_FORMAT_S16);
		SetOutputBytesPerSample (2);
		break;
	case 2: // 16 bit audio
		err = snd_pcm_hw_params_set_format (pcm, params, SND_PCM_FORMAT_S16);
		SetOutputBytesPerSample (2);
		break;
	case 3: // 24 bit audio
		// write as 32 bit audio, this is a lot easier to write to than 24 bit.
		err = snd_pcm_hw_params_set_format (pcm, params, SND_PCM_FORMAT_S32);
//.........这里部分代码省略.........

void SetupSound(void)
{
 snd_pcm_hw_params_t *hwparams;
 snd_pcm_sw_params_t *swparams;
 snd_pcm_status_t *status;
 int pspeed;
 int pchannels;
 int format;
 int buffer_time;
 int period_time;
 int err;

 if(iDisStereo) pchannels=1;
 else pchannels=2;

 pspeed=48000;
 format=SND_PCM_FORMAT_S16_LE;
 buffer_time=500000;
 period_time=buffer_time/4;

 if((err=snd_pcm_open(&handle, "default", 
                      SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK))<0)
  {
   printf("Audio open error: %s\n", snd_strerror(err));
   return;
  }

 if((err=snd_pcm_nonblock(handle, 0))<0)
  {
   printf("Can't set blocking moded: %s\n", snd_strerror(err));
   return;
  }

 snd_pcm_hw_params_alloca(&hwparams);
 snd_pcm_sw_params_alloca(&swparams);
 if((err=snd_pcm_hw_params_any(handle, hwparams))<0)
  {
   printf("Broken configuration for this PCM: %s\n", snd_strerror(err));
   return;
  }

 if((err=snd_pcm_hw_params_set_access(handle, hwparams, SND_PCM_ACCESS_RW_INTERLEAVED))<0)
  {
   printf("Access type not available: %s\n", snd_strerror(err));
   return;
  }

 if((err=snd_pcm_hw_params_set_format(handle, hwparams, format))<0)
  {
   printf("Sample format not available: %s\n", snd_strerror(err));
   return;
  }

 if((err=snd_pcm_hw_params_set_channels(handle, hwparams, pchannels))<0)
  {
   printf("Channels count not available: %s\n", snd_strerror(err));
   return;
  }

 if((err=snd_pcm_hw_params_set_rate_near(handle, hwparams, &pspeed, 0))<0)
  {
   printf("Rate not available: %s\n", snd_strerror(err));
   return;
  }

 if((err=snd_pcm_hw_params_set_buffer_time_near(handle, hwparams, &buffer_time, 0))<0)
  {
   printf("Buffer time error: %s\n", snd_strerror(err));
   return;
  }

 if((err=snd_pcm_hw_params_set_period_time_near(handle, hwparams, &period_time, 0))<0)
  {
   printf("Period time error: %s\n", snd_strerror(err));
   return;
  }

 if((err=snd_pcm_hw_params(handle, hwparams))<0)
  {
   printf("Unable to install hw params: %s\n", snd_strerror(err));
   return;
  }

 snd_pcm_status_alloca(&status);
 if((err=snd_pcm_status(handle, status))<0)
  {
   printf("Unable to get status: %s\n", snd_strerror(err));
   return;
  }

 buffer_size=snd_pcm_status_get_avail(status);
}

/* Initialise audio devices. */
int digi_init()
{
	int err, tmp;
	char *device = "plughw:0,0";
	snd_pcm_hw_params_t *params;
 pthread_attr_t attr;
 pthread_mutexattr_t mutexattr;

 //added on 980905 by adb to init sound kill system
 memset(SampleHandles, 255, sizeof(SampleHandles));
 //end edit by adb

 /* Open the ALSA sound device */
	if ((err = snd_pcm_open(&snd_devhandle, device, SND_PCM_STREAM_PLAYBACK)) < 0)
	{
     con_printf(CON_CRITICAL, "open failed: %s\n", snd_strerror( err ));  
     return -1; 
	}

	snd_pcm_hw_params_alloca(&params);
	err = snd_pcm_hw_params_any(snd_devhandle, params);
	if (err < 0)
	{
		con_printf(CON_CRITICAL,"ALSA: Error %s\n", snd_strerror(err));
		return -1;
	}
	err = snd_pcm_hw_params_set_access(snd_devhandle, params, SND_PCM_ACCESS_RW_INTERLEAVED);
	if (err < 0)
	{
		con_printf(CON_CRITICAL,"ALSA: Error %s\n", snd_strerror(err));
		return -1;
	}
	err = snd_pcm_hw_params_set_format(snd_devhandle, params, SND_PCM_FORMAT_U8);
	if (err < 0)
	{
		con_printf(CON_CRITICAL,"ALSA: Error %s\n", snd_strerror(err));
		return -1;
	}
	err = snd_pcm_hw_params_set_channels(snd_devhandle, params, 2);
	if (err < 0)
	{
		con_printf(CON_CRITICAL,"ALSA: Error %s\n", snd_strerror(err));
		return -1;
	}
	tmp = 11025;
	err = snd_pcm_hw_params_set_rate_near(snd_devhandle, params, &tmp, NULL);
	if (err < 0)
	{
		con_printf(CON_CRITICAL,"ALSA: Error %s\n", snd_strerror(err));
		return -1;
	}
	snd_pcm_hw_params_set_periods(snd_devhandle, params, 3, 0);
	snd_pcm_hw_params_set_buffer_size(snd_devhandle,params, (SOUND_BUFFER_SIZE*3)/2);

	err = snd_pcm_hw_params(snd_devhandle, params);
	if (err < 0)
	{
		con_printf(CON_CRITICAL,"ALSA: Error %s\n", snd_strerror(err));
		return -1;
	}

 /* Start the mixer thread */

 /* We really should check the results of these */
 pthread_mutexattr_init(&mutexattr);
 pthread_mutex_init(&mutex,&mutexattr);
 pthread_mutexattr_destroy(&mutexattr);
 
 if (pthread_attr_init(&attr) != 0) {
  con_printf(CON_CRITICAL, "failed to init attr\n");
  snd_pcm_close( snd_devhandle ); 
  return -1;
 }

 pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);

 pthread_create(&thread_id,&attr,mixer_thread,NULL);
 pthread_attr_destroy(&attr);

 digi_initialised = 1;
 return 0;
}

/**
 * This method prepares ALSA system for 22050hz signed 16bits Little Endian
 * playback.
 */
void SoundThread::initAlsa()
{
	int err;
	ostringstream oss;

	/* Get a handle on the PCM device. */

	if ((err = snd_pcm_open (&playback_handle, deviceName, SND_PCM_STREAM_PLAYBACK, 0)) < 0)
	{
		oss << "cannot open audio device : " << deviceName << snd_strerror(err) << endl;
		throw oss.str();
	}

	/* Allocate snd_pcm_hw_params_t structure. */
	if ((err = snd_pcm_hw_params_malloc (&hw_params)) < 0)
	{
		oss << "cannot allocate hardware parameter structure : " << snd_strerror (err) << endl;
		throw oss.str();
	}

	/* Retrieve current parameters. */
	if ((err = snd_pcm_hw_params_any (playback_handle, hw_params)) < 0)
	{
		oss << "cannot initialize hardware parameter structure : " << snd_strerror (err) << endl;
		throw oss.str();
	}


	/* Set Sample are NON Interleaved (mono !) */
	if ((err = snd_pcm_hw_params_set_access (playback_handle, hw_params, SND_PCM_ACCESS_RW_NONINTERLEAVED)) < 0)
	{
		oss << "cannot set access type : " << snd_strerror (err) << endl;
		throw oss.str();
	}

	/* Set Sample format: Signed 16bit little endian. */
	if ((err = snd_pcm_hw_params_set_format (playback_handle, hw_params, SND_PCM_FORMAT_S16_LE)) < 0)
	{
		oss << "cannot set sample format : " << snd_strerror (err) << endl;
		throw oss.str();
	}

	/* Set the Sample rate. */
	if ((err = snd_pcm_hw_params_set_rate (playback_handle, hw_params, 22050, 0)) < 0)
	{
		oss << "cannot set sample rate : " << snd_strerror (err) << endl;
		throw oss.str();
	}

	/* Set Channel number (MONO). */
	if ((err = snd_pcm_hw_params_set_channels (playback_handle, hw_params, 1)) < 0)
	{
		oss << "cannot set channel count : " << snd_strerror (err) << endl;
		throw oss.str();
	}


	if ((err = snd_pcm_hw_params_set_buffer_size(playback_handle, hw_params, 2048)) < 0)
	{
		oss << "cannot set channel buffer size : " << snd_strerror (err) << endl;
		throw oss.str();
	}



	/* Apply these parameters. */
	if ((err = snd_pcm_hw_params (playback_handle, hw_params)) < 0)
	{
		oss << "cannot apply parameters : " << snd_strerror (err) << endl;
		throw oss.str();
	}

	snd_pcm_uframes_t bufferSize;
	snd_pcm_hw_params_get_buffer_size( hw_params, &bufferSize );
	//cout << "initAlsa: Buffer size = " << bufferSize << " frames." << endl;

	/* Free memoray allocated for snd_pcm_hw_params_t */
	snd_pcm_hw_params_free (hw_params);

	/* tell ALSA to wake us up whenever 4096 or more frames
	   of playback data can be delivered. Also, tell
	   ALSA that we'll start the device ourselves.
	*/

	/* Allocate snd_pcm_sw_params_t structure. */
	if ((err = snd_pcm_sw_params_malloc (&sw_params)) < 0)
	{
		oss << "cannot allocate software parameters structure : " << snd_strerror (err) << endl;
		throw oss.str();
	}

	/* Get the current software configuration*/
	if ((err = snd_pcm_sw_params_current (playback_handle, sw_params)) < 0)
	{
		oss << "cannot initialize software parameters structure : " << snd_strerror (err) << endl;
		throw oss.str();
//.........这里部分代码省略.........