C++ snd_pcm_resume函数代码示例

static void CheckXRUN(IDsCaptureDriverBufferImpl* This)
{
    snd_pcm_state_t state = snd_pcm_state(This->pcm);
    snd_pcm_sframes_t delay;
    int err;

    snd_pcm_hwsync(This->pcm);
    snd_pcm_delay(This->pcm, &delay);
    if ( state == SND_PCM_STATE_XRUN )
    {
        err = snd_pcm_prepare(This->pcm);
        CommitAll(This, FALSE);
        snd_pcm_start(This->pcm);
        WARN("xrun occurred\n");
        if ( err < 0 )
            ERR("recovery from xrun failed, prepare failed: %s\n", snd_strerror(err));
    }
    else if ( state == SND_PCM_STATE_SUSPENDED )
    {
        int err = snd_pcm_resume(This->pcm);
        TRACE("recovery from suspension occurred\n");
        if (err < 0 && err != -EAGAIN){
            err = snd_pcm_prepare(This->pcm);
            if (err < 0)
                ERR("recovery from suspend failed, prepare failed: %s\n", snd_strerror(err));
        }
    }
    else if ( state != SND_PCM_STATE_RUNNING)
    {
        WARN("Unhandled state: %d\n", state);
    }
}

int QAudioInputPrivate::xrun_recovery(int err)
{
    int  count = 0;
    bool reset = false;

    if(err == -EPIPE) {
        errorState = QAudio::UnderrunError;
        err = snd_pcm_prepare(handle);
        if(err < 0)
            reset = true;

    } else if((err == -ESTRPIPE)||(err == -EIO)) {
        errorState = QAudio::IOError;
        while((err = snd_pcm_resume(handle)) == -EAGAIN){
            usleep(100);
            count++;
            if(count > 5) {
                reset = true;
                break;
            }
        }
        if(err < 0) {
            err = snd_pcm_prepare(handle);
            if(err < 0)
                reset = true;
        }
    }
    if(reset) {
        close();
        open();
        snd_pcm_prepare(handle);
        return 0;
    }
    return err;
}

void CAESinkALSA::HandleError(const char* name, int err)
{
  switch(err)
  {
    case -EPIPE:
      CLog::Log(LOGERROR, "CAESinkALSA::HandleError(%s) - underrun", name);
      if ((err = snd_pcm_prepare(m_pcm)) < 0)
        CLog::Log(LOGERROR, "CAESinkALSA::HandleError(%s) - snd_pcm_prepare returned %d (%s)", name, err, snd_strerror(err));
      break;

    case -ESTRPIPE:
      CLog::Log(LOGINFO, "CAESinkALSA::HandleError(%s) - Resuming after suspend", name);

      /* try to resume the stream */
      while((err = snd_pcm_resume(m_pcm)) == -EAGAIN)
        Sleep(1);

      /* if the hardware doesnt support resume, prepare the stream */
      if (err == -ENOSYS)
        if ((err = snd_pcm_prepare(m_pcm)) < 0)
          CLog::Log(LOGERROR, "CAESinkALSA::HandleError(%s) - snd_pcm_prepare returned %d (%s)", name, err, snd_strerror(err));
      break;

    default:
      CLog::Log(LOGERROR, "CAESinkALSA::HandleError(%s) - snd_pcm_writei returned %d (%s)", name, err, snd_strerror(err));
      break;
  }
}

int snd_pcm_recover(snd_pcm_t *pcm, int err, int silent)
{
        if (err > 0)
                err = -err;
        if (err == -EINTR)	/* nothing to do, continue */
                return 0;
        if (err == -EPIPE) {
                err = snd_pcm_prepare(pcm);
                if (err < 0)
                        return err;
                return 0;
        }
        if (err == -ESTRPIPE) {
                while ((err = snd_pcm_resume(pcm)) == -EAGAIN)
                        /* wait until suspend flag is released */
                        poll(NULL, 0, 1000);
                if (err < 0) {
                        err = snd_pcm_prepare(pcm);
                        if (err < 0)
                                return err;
                }
                return 0;
        }
        return err;
}

/*
 *   Underrun and suspend recovery
 */
static gint
xrun_recovery (GstAlsaSink * alsa, snd_pcm_t * handle, gint err)
{
  GST_WARNING_OBJECT (alsa, "xrun recovery %d: %s", err, g_strerror (-err));

  if (err == -EPIPE) {          /* under-run */
    err = snd_pcm_prepare (handle);
    if (err < 0)
      GST_WARNING_OBJECT (alsa,
          "Can't recover from underrun, prepare failed: %s",
          snd_strerror (err));
    gst_audio_base_sink_report_device_failure (GST_AUDIO_BASE_SINK (alsa));
    return 0;
  } else if (err == -ESTRPIPE) {
    while ((err = snd_pcm_resume (handle)) == -EAGAIN)
      g_usleep (100);           /* wait until the suspend flag is released */

    if (err < 0) {
      err = snd_pcm_prepare (handle);
      if (err < 0)
        GST_WARNING_OBJECT (alsa,
            "Can't recover from suspend, prepare failed: %s",
            snd_strerror (err));
    }
    if (err == 0)
      gst_audio_base_sink_report_device_failure (GST_AUDIO_BASE_SINK (alsa));
    return 0;
  }
  return err;
}

/*
 *   Underrun and suspend recovery
 */
static gint
xrun_recovery (GstAlsaSink * alsa, snd_pcm_t * handle, gint err)
{
  GST_DEBUG_OBJECT (alsa, "xrun recovery %d", err);

  if (err == -EPIPE) {          /* under-run */
    err = snd_pcm_prepare (handle);
    if (err < 0)
      GST_WARNING_OBJECT (alsa,
          "Can't recovery from underrun, prepare failed: %s",
          snd_strerror (err));
    return 0;
  } else if (err == -ESTRPIPE) {
    while ((err = snd_pcm_resume (handle)) == -EAGAIN)
      g_usleep (100);           /* wait until the suspend flag is released */

    if (err < 0) {
      err = snd_pcm_prepare (handle);
      if (err < 0)
        GST_WARNING_OBJECT (alsa,
            "Can't recovery from suspend, prepare failed: %s",
            snd_strerror (err));
    }
    return 0;
  }
  return err;
}

int DAUDIO_Start(void* id, int isSource) {
    AlsaPcmInfo* info = (AlsaPcmInfo*) id;
    int ret;
    snd_pcm_state_t state;

    TRACE0("> DAUDIO_Start\n");
    // set to blocking mode
    snd_pcm_nonblock(info->handle, 0);
    // set start mode so that it always starts as soon as data is there
    setStartThreshold(info, TRUE /* use threshold */);
    state = snd_pcm_state(info->handle);
    if (state == SND_PCM_STATE_PAUSED) {
        // in case it was stopped previously
        TRACE0("  Un-pausing...\n");
        ret = snd_pcm_pause(info->handle, FALSE);
        if (ret != 0) {
            ERROR2("  NOTE: error in snd_pcm_pause:%d: %s\n", ret, snd_strerror(ret));
        }
    }
    if (state == SND_PCM_STATE_SUSPENDED) {
        TRACE0("  Resuming...\n");
        ret = snd_pcm_resume(info->handle);
        if (ret < 0) {
            if ((ret != -EAGAIN) && (ret != -ENOSYS)) {
                ERROR2("  ERROR: error in snd_pcm_resume:%d: %s\n", ret, snd_strerror(ret));
            }
        }
    }
    if (state == SND_PCM_STATE_SETUP) {
        TRACE0("need to call prepare again...\n");
        // prepare device
        ret = snd_pcm_prepare(info->handle);
        if (ret < 0) {
            ERROR1("ERROR: snd_pcm_prepare: %s\n", snd_strerror(ret));
        }
    }
    // in case there is still data in the buffers
    ret = snd_pcm_start(info->handle);
    if (ret != 0) {
        if (ret != -EPIPE) {
            ERROR2("  NOTE: error in snd_pcm_start: %d: %s\n", ret, snd_strerror(ret));
        }
    }
    // set to non-blocking mode
    ret = snd_pcm_nonblock(info->handle, 1);
    if (ret != 0) {
        ERROR1("  ERROR in snd_pcm_nonblock: %s\n", snd_strerror(ret));
    }
    state = snd_pcm_state(info->handle);
#ifdef USE_TRACE
    printState(state);
#endif
    ret = (state == SND_PCM_STATE_PREPARED)
        || (state == SND_PCM_STATE_RUNNING)
        || (state == SND_PCM_STATE_XRUN)
        || (state == SND_PCM_STATE_SUSPENDED);
    TRACE1("< DAUDIO_Start %s\n", ret?"success":"error");
    return ret?TRUE:FALSE;
}

/* Play from alsa_buf as many chunks as possible. Move the remaining data
 * to the beginning of the buffer. Return the number of bytes written
 * or -1 on error. */
static int play_buf_chunks ()
{
	int written = 0;
	
	while (alsa_buf_fill >= chunk_size) {
		int err;
		
		err = snd_pcm_writei (handle, alsa_buf + written,
				chunk_size / bytes_per_frame);
		if (err == -EAGAIN) {
			if (snd_pcm_wait(handle, 500) < 0)
				logit ("snd_pcm_wait() failed");
		}
		else if (err == -EPIPE) {
			logit ("underrun!");
			if ((err = snd_pcm_prepare(handle)) < 0) {
				error ("Can't recover after underrun: %s",
						snd_strerror(err));
				/* TODO: reopen the device */
				return -1;
			}
		}
		else if (err == -ESTRPIPE) {
			logit ("Suspend, trying to resume");
			while ((err = snd_pcm_resume(handle))
					== -EAGAIN)
				sleep (1);
			if (err < 0) {
				logit ("Failed, restarting");
				if ((err = snd_pcm_prepare(handle))
						< 0) {
					error ("Failed to restart "
							"device: %s.",
							snd_strerror(err));
					return -1;
				}
			}
		}
		else if (err < 0) {
			error ("Can't play: %s", snd_strerror(err));
			return -1;
		}
		else {
			int written_bytes = err * bytes_per_frame;

			written += written_bytes;
			alsa_buf_fill -= written_bytes;

			debug ("Played %d bytes", written_bytes);
		}
	}

	debug ("%d bytes remain in alsa_buf", alsa_buf_fill);
	memmove (alsa_buf, alsa_buf + written, alsa_buf_fill);

	return written * bytes_per_frame;
}

static void
alsaspdifsink_write_frame (AlsaSPDIFSink * sink, guchar * buf)
{
  snd_pcm_sframes_t res;
  int num_frames = IEC958_FRAME_SIZE / ALSASPDIFSINK_BYTES_PER_FRAME;

  /* If we couldn't output big endian when we opened the devic, then
   * we need to swap here */
  if (sink->need_swap) {
    int i;
    guchar tmp;

    for (i = 0; i < IEC958_FRAME_SIZE; i += 2) {
      tmp = buf[i];
      buf[i] = buf[i + 1];
      buf[i + 1] = tmp;
    }
  }

  res = 0;
  do {
    if (res == -EPIPE) {
      /* Underrun. */
      GST_INFO_OBJECT (sink, "buffer underrun");
      res = snd_pcm_prepare (sink->pcm);
    } else if (res == -ESTRPIPE) {
      /* Suspend. */
      while ((res = snd_pcm_resume (sink->pcm)) == -EAGAIN) {
        GST_DEBUG_OBJECT (sink, "sleeping for suspend");
        g_usleep (100000);
      }

      if (res < 0) {
        res = snd_pcm_prepare (sink->pcm);
      }
    }

    if (res >= 0) {
      res = snd_pcm_writei (sink->pcm, (void *) buf, num_frames);
    }

    if (res > 0) {
      num_frames -= res;
    }

  } while (res == -EPIPE || num_frames > 0);

  sink->frames++;

  if (res < 0) {
    GST_ELEMENT_ERROR (sink, RESOURCE, OPEN_WRITE,
        ("writei returned error: %s", snd_strerror (res)), GST_ERROR_SYSTEM);
    return;
  }
}

static int drvHostALSAAudioResume(snd_pcm_t *phPCM)
{
    AssertPtrReturn(phPCM, VERR_INVALID_POINTER);

    int err = snd_pcm_resume(phPCM);
    if (err < 0)
    {
        LogFunc(("Failed to resume stream %p: %s\n",
                 phPCM, snd_strerror(err)));
        return VERR_ACCESS_DENIED; /** @todo Find a better rc. */
    }

    return VINF_SUCCESS;
}

static int
laudio_alsa_xrun_recover(int err)
{
  int ret;

  if (err != 0)
    pcm_last_error = err;

  /* Buffer underrun */
  if (err == -EPIPE)
    {
      pcm_last_error = 0;

      ret = snd_pcm_prepare(hdl);
      if (ret < 0)
	{
	  DPRINTF(E_WARN, L_LAUDIO, "Couldn't recover from underrun: %s\n", snd_strerror(ret));
	  return 1;
	}

      return 0;
    }
  /* Device suspended */
  else if (pcm_last_error == -ESTRPIPE)
    {
      ret = snd_pcm_resume(hdl);
      if (ret == -EAGAIN)
	{
	  pcm_recovery++;

	  return 2;
	}
      else if (ret < 0)
	{
	  pcm_recovery = 0;

	  ret = snd_pcm_prepare(hdl);
	  if (ret < 0)
	    {
	      DPRINTF(E_WARN, L_LAUDIO, "Couldn't recover from suspend: %s\n", snd_strerror(ret));
	      return 1;
	    }
	}

      pcm_recovery = 0;
      return 0;
    }

  return err;
}

static int ao_alsa_play(dtaudio_output_t *aout, uint8_t * buf, int size)
{
    alsa_ctx_t *ctx = (alsa_ctx_t *)wrapper->ao_priv;
    snd_pcm_t *alsa_handle = (snd_pcm_t *) ctx->handle;

    int bytes_per_sample = wrapper->para.bps * wrapper->para.dst_channels / 8;
    int num_frames = size / bytes_per_sample;
    snd_pcm_sframes_t res = 0;
    uint8_t *data = buf;

    if (!alsa_handle) {
        return -1;
    }

    if (num_frames == 0) {
        return 0;
    }

    if (ao_alsa_level(aout) >= ctx->buf_threshold) {
        dt_debug(TAG, "ALSA EXCEED THRESHOLD,size:%d  thres:%d \n", ao_alsa_level(aout),
                 ctx->buf_threshold);
        return 0;
    }

    res = snd_pcm_writei(alsa_handle, data, num_frames);
    if (res == -EINTR) {
        dt_info(TAG, "ALSA HAS NO SPACE, WRITE AGAIN\n");
        return res;
    }
    if (res == -ESTRPIPE) {
        snd_pcm_resume(alsa_handle);
        return res;
    }
    if (res == -EBADFD) {
        snd_pcm_reset(alsa_handle);
        return res;
    }
    if (res < 0) {
        snd_pcm_prepare(alsa_handle);
        dt_info(TAG, "snd pcm write failed prepare!\n");
        return -1;
        //goto rewrite;
    }
    if (res < num_frames) {
        data += res * bytes_per_sample;
        num_frames -= res;
        //goto rewrite;
    }
    return res * bytes_per_sample;
}

static int recover(sox_format_t * ft, snd_pcm_t * pcm, int err)
{
  if (err == -EPIPE)
    lsx_warn("%s-run", ft->mode == 'r'? "over" : "under");
  else if (err != -ESTRPIPE)
    lsx_warn("%s", snd_strerror(err));
  else while ((err = snd_pcm_resume(pcm)) == -EAGAIN) {
    lsx_report("suspended");
    sleep(1);                  /* Wait until the suspend flag is released */
  }
  if (err < 0 && (err = snd_pcm_prepare(pcm)) < 0)
    lsx_fail_errno(ft, SOX_EPERM, "%s", snd_strerror(err));
  return err;
}

static int
suspend_recover(void) {
	int err;

	while((err = snd_pcm_resume(alsa_pcm)) == -EAGAIN)
		/* wait until suspend flag is released */
		sleep(1);

	if(err < 0) {
		printf("alsa_handle_error(): " "snd_pcm_resume() failed.\n");
		return snd_pcm_prepare(alsa_pcm);
	}

	return err;
}

static void suspend(void)
{
  int res;

  fprintf(stderr, "Suspended. Trying resume. "); fflush(stderr);
  while ((res = snd_pcm_resume(AHandle)) == -EAGAIN)
    sleep(1);	/* wait until suspend flag is released */
  if (res < 0) {
    fprintf(stderr, "Failed. Restarting stream. "); fflush(stderr);
    if ((res = snd_pcm_prepare(AHandle)) < 0) {
      fprintf(stderr, "suspend: prepare error: %s", snd_strerror(res));
    }
  }
  fprintf(stderr, "Done.\n");
}