text: /*************************************************************************/
  /*  audio_server.h                                                       */
  /*************************************************************************/
  /*                       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.                */
  /*************************************************************************/
  
  #ifndef AUDIO_SERVER_H
  #define AUDIO_SERVER_H
  
  #include "audio_frame.h"
  #include "object.h"
  #include "servers/audio/audio_effect.h"
  #include "variant.h"
  
  class AudioDriverDummy;
  
  class AudioDriver {
  
  	static AudioDriver *singleton;
  	uint64_t _last_mix_time;
  	uint64_t _mix_amount;
  
  protected:
  	void audio_server_process(int p_frames, int32_t *p_buffer, bool p_update_mix_time = true);
  	void update_mix_time(int p_frames);
  
  public:
  	double get_mix_time() const; //useful for video -> audio sync
  
  	enum SpeakerMode {
  		SPEAKER_MODE_STEREO,
  		SPEAKER_SURROUND_31,
  		SPEAKER_SURROUND_51,
  		SPEAKER_SURROUND_71,
  	};
  
  	static const int DEFAULT_MIX_RATE = 44100;
  	static const int DEFAULT_OUTPUT_LATENCY = 15;
  
  	static AudioDriver *get_singleton();
  	void set_singleton();
  
  	virtual const char *get_name() const = 0;
  
  	virtual Error init() = 0;
  	virtual void start() = 0;
  	virtual int get_mix_rate() const = 0;
  	virtual SpeakerMode get_speaker_mode() const = 0;
  	virtual Array get_device_list();
  	virtual String get_device();
  	virtual void set_device(String device) {}
  	virtual void lock() = 0;
  	virtual void unlock() = 0;
  	virtual void finish() = 0;
  
  	virtual float get_latency() { return 0; }
  
  	SpeakerMode get_speaker_mode_by_total_channels(int p_channels) const;
  	int get_total_channels_by_speaker_mode(SpeakerMode) const;
  
  	AudioDriver();
  	virtual ~AudioDriver() {}
  };
  
  class AudioDriverManager {
  
  	enum {
  
  		MAX_DRIVERS = 10
  	};
  
  	static AudioDriver *drivers[MAX_DRIVERS];
  	static int driver_count;
  
  	static AudioDriverDummy dummy_driver;
  
  public:
  	static void add_driver(AudioDriver *p_driver);
  	static void initialize(int p_driver);
  	static int get_driver_count();
  	static AudioDriver *get_driver(int p_driver);
  };
  
  class AudioBusLayout;
  
  class AudioServer : public Object {
  
  	GDCLASS(AudioServer, Object)
  public:
  	//re-expose this her, as AudioDriver is not exposed to script
  	enum SpeakerMode {
  		SPEAKER_MODE_STEREO,
  		SPEAKER_SURROUND_31,
  		SPEAKER_SURROUND_51,
  		SPEAKER_SURROUND_71,
  	};
  
  	enum {
  		AUDIO_DATA_INVALID_ID = -1
  	};
  
  	typedef void (*AudioCallback)(void *p_userdata);
  
  private:
  	uint32_t buffer_size;
  	uint64_t mix_count;
  	uint64_t mix_frames;
  
  	float channel_disable_threshold_db;
  	uint32_t channel_disable_frames;
  
  	int channel_count;
  	int to_mix;
  
  	struct Bus {
  
  		StringName name;
  		bool solo;
  		bool mute;
  		bool bypass;
  
  		bool soloed;
  
  		//Each channel is a stereo pair.
  		struct Channel {
  			bool used;
  			bool active;
  			AudioFrame peak_volume;
  			Vector<AudioFrame> buffer;
  			Vector<Ref<AudioEffectInstance> > effect_instances;
  			uint64_t last_mix_with_audio;
  			Channel() {
  				last_mix_with_audio = 0;
  				used = false;
  				active = false;
  				peak_volume = AudioFrame(0, 0);
  			}
  		};
  
  		Vector<Channel> channels;
  
  		struct Effect {
  			Ref<AudioEffect> effect;
  			bool enabled;
  		};
  
  		Vector<Effect> effects;
  		float volume_db;
  		StringName send;
  		int index_cache;
  	};
  
  	Vector<Vector<AudioFrame> > temp_buffer; //temp_buffer for each level
  	Vector<Bus *> buses;
  	Map<StringName, Bus *> bus_map;
  
  	void _update_bus_effects(int p_bus);
  
  	static AudioServer *singleton;
  
  	// TODO create an audiodata pool to optimize memory
  
  	Map<void *, uint32_t> audio_data;
  	size_t audio_data_total_mem;
  	size_t audio_data_max_mem;
  
  	Mutex *audio_data_lock;
  
  	void init_channels_and_buffers();
  
  	void _mix_step();
  
  	struct CallbackItem {
  
  		AudioCallback callback;
  		void *userdata;
  
  		bool operator<(const CallbackItem &p_item) const {
  			return (callback == p_item.callback ? userdata < p_item.userdata : callback < p_item.callback);
  		}
  	};
  
  	Set<CallbackItem> callbacks;
  
  	friend class AudioDriver;
  	void _driver_process(int p_frames, int32_t *p_buffer);
  
  protected:
  	static void _bind_methods();
  
  public:
  	_FORCE_INLINE_ int get_channel_count() const {
  		switch (get_speaker_mode()) {
  			case SPEAKER_MODE_STEREO: return 1;
  			case SPEAKER_SURROUND_31: return 2;
  			case SPEAKER_SURROUND_51: return 3;
  			case SPEAKER_SURROUND_71: return 4;
  		}
  		ERR_FAIL_V(1);
  	}
  
  	//do not use from outside audio thread
  	AudioFrame *thread_get_channel_mix_buffer(int p_bus, int p_buffer);
  	int thread_get_mix_buffer_size() const;
  	int thread_find_bus_index(const StringName &p_name);
  
  	void set_bus_count(int p_count);
  	int get_bus_count() const;
  
  	void remove_bus(int p_index);
  	void add_bus(int p_at_pos = -1);
  
  	void move_bus(int p_bus, int p_to_pos);
  
  	void set_bus_name(int p_bus, const String &p_name);
  	String get_bus_name(int p_bus) const;
  	int get_bus_index(const StringName &p_bus_name) const;
  
  	void set_bus_volume_db(int p_bus, float p_volume_db);
  	float get_bus_volume_db(int p_bus) const;
  
  	void set_bus_send(int p_bus, const StringName &p_send);
  	StringName get_bus_send(int p_bus) const;
  
  	void set_bus_solo(int p_bus, bool p_enable);
  	bool is_bus_solo(int p_bus) const;
  
  	void set_bus_mute(int p_bus, bool p_enable);
  	bool is_bus_mute(int p_bus) const;
  
  	void set_bus_bypass_effects(int p_bus, bool p_enable);
  	bool is_bus_bypassing_effects(int p_bus) const;
  
  	void add_bus_effect(int p_bus, const Ref<AudioEffect> &p_effect, int p_at_pos = -1);
  	void remove_bus_effect(int p_bus, int p_effect);
  
  	int get_bus_effect_count(int p_bus);
  	Ref<AudioEffect> get_bus_effect(int p_bus, int p_effect);
  
  	void swap_bus_effects(int p_bus, int p_effect, int p_by_effect);
  
  	void set_bus_effect_enabled(int p_bus, int p_effect, bool p_enabled);
  	bool is_bus_effect_enabled(int p_bus, int p_effect) const;
  
  	float get_bus_peak_volume_left_db(int p_bus, int p_channel) const;
  	float get_bus_peak_volume_right_db(int p_bus, int p_channel) const;
  
  	bool is_bus_channel_active(int p_bus, int p_channel) const;
  
  	virtual void init();
  	virtual void finish();
  	virtual void load_default_bus_layout();
  
  	/* MISC config */
  
  	virtual void lock();
  	virtual void unlock();
  
  	virtual SpeakerMode get_speaker_mode() const;
  	virtual float get_mix_rate() const;
  
  	virtual float read_output_peak_db() const;
  
  	static AudioServer *get_singleton();
  
  	virtual double get_mix_time() const; //useful for video -> audio sync
  	virtual double get_output_delay() const;
  
  	void *audio_data_alloc(uint32_t p_data_len, const uint8_t *p_from_data = NULL);
  	void audio_data_free(void *p_data);
  
  	size_t audio_data_get_total_memory_usage() const;
  	size_t audio_data_get_max_memory_usage() const;
  
  	void add_callback(AudioCallback p_callback, void *p_userdata);
  	void remove_callback(AudioCallback p_callback, void *p_userdata);
  
  	void set_bus_layout(const Ref<AudioBusLayout> &p_bus_layout);
  	Ref<AudioBusLayout> generate_bus_layout() const;
  
  	Array get_device_list();
  	String get_device();
  	void set_device(String device);
  
  	AudioServer();
  	virtual ~AudioServer();
  };
  
  VARIANT_ENUM_CAST(AudioServer::SpeakerMode)
  
  class AudioBusLayout : public Resource {
  
  	GDCLASS(AudioBusLayout, Resource)
  
  	friend class AudioServer;
  
  	struct Bus {
  
  		StringName name;
  		bool solo;
  		bool mute;
  		bool bypass;
  
  		struct Effect {
  			Ref<AudioEffect> effect;
  			bool enabled;
  		};
  
  		Vector<Effect> effects;
  
  		float volume_db;
  		StringName send;
  
  		Bus() {
  			solo = false;
  			mute = false;
  			bypass = false;
  			volume_db = 0;
  		}
  	};
  
  	Vector<Bus> buses;
  
  protected:
  	bool _set(const StringName &p_name, const Variant &p_value);
  	bool _get(const StringName &p_name, Variant &r_ret) const;
  	void _get_property_list(List<PropertyInfo> *p_list) const;
  
  public:
  	AudioBusLayout();
  };
  
  typedef AudioServer AS;
  
  #endif // AUDIO_SERVER_H
  