text: /*************************************************************************/
  /*  audio_driver_rtaudio.cpp                                             */
  /*************************************************************************/
  /*                       This file is part of:                           */
  /*                           GODOT ENGINE                                */
  /*                      https://godotengine.org                          */
  /*************************************************************************/
  /* Copyright (c) 2007-2018 Juan Linietsky, Ariel Manzur.                 */
  /* Copyright (c) 2014-2018 Godot Engine contributors (cf. AUTHORS.md)    */
  /*                                                                       */
  /* Permission is hereby granted, free of charge, to any person obtaining */
  /* a copy of this software and associated documentation files (the       */
  /* "Software"), to deal in the Software without restriction, including   */
  /* without limitation the rights to use, copy, modify, merge, publish,   */
  /* distribute, sublicense, and/or sell copies of the Software, and to    */
  /* permit persons to whom the Software is furnished to do so, subject to */
  /* the following conditions:                                             */
  /*                                                                       */
  /* The above copyright notice and this permission notice shall be        */
  /* included in all copies or substantial portions of the Software.       */
  /*                                                                       */
  /* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
  /* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
  /* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
  /* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
  /* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
  /* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
  /* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
  /*************************************************************************/
  
  #include "audio_driver_rtaudio.h"
  
  #include "core/os/os.h"
  #include "core/project_settings.h"
  
  #ifdef RTAUDIO_ENABLED
  
  const char *AudioDriverRtAudio::get_name() const {
  
  #ifdef OSX_ENABLED
  	return "RtAudio-OSX";
  #elif defined(UNIX_ENABLED)
  	return "RtAudio-ALSA";
  #elif defined(WINDOWS_ENABLED)
  	return "RtAudio-DirectSound";
  #else
  	return "RtAudio-None";
  #endif
  }
  
  int AudioDriverRtAudio::callback(void *outputBuffer, void *inputBuffer, unsigned int nBufferFrames, double streamTime, RtAudioStreamStatus status, void *userData) {
  
  	if (status) {
  		if (status & RTAUDIO_INPUT_OVERFLOW) {
  			WARN_PRINT("RtAudio input overflow!");
  		}
  		if (status & RTAUDIO_OUTPUT_UNDERFLOW) {
  			WARN_PRINT("RtAudio output underflow!");
  		}
  	}
  	int32_t *buffer = (int32_t *)outputBuffer;
  
  	AudioDriverRtAudio *self = (AudioDriverRtAudio *)userData;
  
  	if (self->mutex->try_lock() != OK) {
  		// what should i do..
  		for (unsigned int i = 0; i < nBufferFrames; i++)
  			buffer[i] = 0;
  
  		return 0;
  	}
  
  	self->audio_server_process(nBufferFrames, buffer);
  
  	self->mutex->unlock();
  
  	return 0;
  }
  
  Error AudioDriverRtAudio::init() {
  
  	active = false;
  	mutex = Mutex::create(true);
  	dac = memnew(RtAudio);
  
  	ERR_EXPLAIN("Cannot initialize RtAudio audio driver: No devices present.")
  	ERR_FAIL_COND_V(dac->getDeviceCount() < 1, ERR_UNAVAILABLE);
  
  	// FIXME: Adapt to the OutputFormat -> SpeakerMode change
  	/*
  	String channels = GLOBAL_DEF_RST("audio/output","stereo");
  
  	if (channels=="5.1")
  		output_format=OUTPUT_5_1;
  	else if (channels=="quad")
  		output_format=OUTPUT_QUAD;
  	else if (channels=="mono")
  		output_format=OUTPUT_MONO;
  	else
  		output_format=OUTPUT_STEREO;
  	*/
  
  	RtAudio::StreamParameters parameters;
  	parameters.deviceId = dac->getDefaultOutputDevice();
  	RtAudio::StreamOptions options;
  
  	// set the desired numberOfBuffers
  	options.numberOfBuffers = 4;
  
  	parameters.firstChannel = 0;
  	mix_rate = GLOBAL_DEF_RST("audio/mix_rate", DEFAULT_MIX_RATE);
  
  	int latency = GLOBAL_DEF("audio/output_latency", DEFAULT_OUTPUT_LATENCY);
  	unsigned int buffer_frames = closest_power_of_2(latency * mix_rate / 1000);
  	print_verbose("Audio buffer frames: " + itos(buffer_frames) + " calculated latency: " + itos(buffer_frames * 1000 / mix_rate) + "ms");
  
  	short int tries = 2;
  
  	while (tries >= 0) {
  		switch (speaker_mode) {
  			case SPEAKER_MODE_STEREO: parameters.nChannels = 2; break;
  			case SPEAKER_SURROUND_51: parameters.nChannels = 6; break;
  			case SPEAKER_SURROUND_71: parameters.nChannels = 8; break;
  		};
  
  		try {
  			dac->openStream(&parameters, NULL, RTAUDIO_SINT32, mix_rate, &buffer_frames, &callback, this, &options);
  			active = true;
  
  			break;
  		} catch (RtAudioError) {
  			// try with less channels
  			ERR_PRINT("Unable to open audio, retrying with fewer channels...");
  
  			switch (speaker_mode) {
  				case SPEAKER_SURROUND_51: speaker_mode = SPEAKER_MODE_STEREO; break;
  				case SPEAKER_SURROUND_71: speaker_mode = SPEAKER_SURROUND_51; break;
  			}
  
  			tries--;
  		}
  	}
  
  	return active ? OK : ERR_UNAVAILABLE;
  }
  
  int AudioDriverRtAudio::get_mix_rate() const {
  
  	return mix_rate;
  }
  
  AudioDriver::SpeakerMode AudioDriverRtAudio::get_speaker_mode() const {
  
  	return speaker_mode;
  }
  
  void AudioDriverRtAudio::start() {
  
  	if (active)
  		dac->startStream();
  }
  
  void AudioDriverRtAudio::lock() {
  
  	if (mutex)
  		mutex->lock();
  }
  
  void AudioDriverRtAudio::unlock() {
  
  	if (mutex)
  		mutex->unlock();
  }
  
  void AudioDriverRtAudio::finish() {
  
  	lock();
  	if (active && dac->isStreamOpen()) {
  		dac->closeStream();
  		active = false;
  	}
  	unlock();
  
  	if (mutex) {
  		memdelete(mutex);
  		mutex = NULL;
  	}
  	if (dac) {
  		memdelete(dac);
  		dac = NULL;
  	}
  }
  
  AudioDriverRtAudio::AudioDriverRtAudio() {
  
  	active = false;
  	mutex = NULL;
  	dac = NULL;
  	mix_rate = DEFAULT_MIX_RATE;
  	speaker_mode = SPEAKER_MODE_STEREO;
  }
  
  #endif
  