/**************************************************************************/
/*  audio_server.cpp                                                      */
/**************************************************************************/
/*                         This file is part of:                          */
/*                             GODOT ENGINE                               */
/*                        https://godotengine.org                         */
/**************************************************************************/
/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
/*                                                                        */
/* 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_server.h"

#include "core/config/project_settings.h"
#include "core/debugger/engine_debugger.h"
#include "core/error/error_macros.h"
#include "core/io/file_access.h"
#include "core/io/resource_loader.h"
#include "core/math/audio_frame.h"
#include "core/os/os.h"
#include "core/string/string_name.h"
#include "core/templates/pair.h"
#include "scene/resources/audio_stream_wav.h"
#include "scene/scene_string_names.h"
#include "servers/audio/audio_driver_dummy.h"
#include "servers/audio/effects/audio_effect_compressor.h"

#include <cstring>

#ifdef TOOLS_ENABLED
#define MARK_EDITED set_edited(true);
#else
#define MARK_EDITED
#endif

AudioDriver *AudioDriver::singleton = nullptr;
AudioDriver *AudioDriver::get_singleton() {
	return singleton;
}

void AudioDriver::set_singleton() {
	singleton = this;
}

void AudioDriver::audio_server_process(int p_frames, int32_t *p_buffer, bool p_update_mix_time) {
	if (p_update_mix_time) {
		update_mix_time(p_frames);
	}

	if (AudioServer::get_singleton()) {
		AudioServer::get_singleton()->_driver_process(p_frames, p_buffer);
	}
}

void AudioDriver::update_mix_time(int p_frames) {
	_last_mix_frames = p_frames;
	if (OS::get_singleton()) {
		_last_mix_time = OS::get_singleton()->get_ticks_usec();
	}
}

double AudioDriver::get_time_since_last_mix() {
	lock();
	uint64_t last_mix_time = _last_mix_time;
	unlock();
	return (OS::get_singleton()->get_ticks_usec() - last_mix_time) / 1000000.0;
}

double AudioDriver::get_time_to_next_mix() {
	lock();
	uint64_t last_mix_time = _last_mix_time;
	uint64_t last_mix_frames = _last_mix_frames;
	unlock();
	double total = (OS::get_singleton()->get_ticks_usec() - last_mix_time) / 1000000.0;
	double mix_buffer = last_mix_frames / (double)get_mix_rate();
	return mix_buffer - total;
}

void AudioDriver::input_buffer_init(int driver_buffer_frames) {
	const int input_buffer_channels = 2;
	input_buffer.resize(driver_buffer_frames * input_buffer_channels * 4);
	input_position = 0;
	input_size = 0;
}

void AudioDriver::input_buffer_write(int32_t sample) {
	if ((int)input_position < input_buffer.size()) {
		input_buffer.write[input_position++] = sample;
		if ((int)input_position >= input_buffer.size()) {
			input_position = 0;
		}
		if ((int)input_size < input_buffer.size()) {
			input_size++;
		}
	} else {
		WARN_PRINT("input_buffer_write: Invalid input_position=" + itos(input_position) + " input_buffer.size()=" + itos(input_buffer.size()));
	}
}

int AudioDriver::_get_configured_mix_rate() {
	StringName audio_driver_setting = "audio/driver/mix_rate";
	int mix_rate = GLOBAL_GET(audio_driver_setting);

	// In the case of invalid mix rate, let's default to a sensible value..
	if (mix_rate <= 0) {
#ifndef WEB_ENABLED
		WARN_PRINT(vformat("Invalid mix rate of %d, consider reassigning setting \'%s\'. \nDefaulting mix rate to value %d.",
				mix_rate, audio_driver_setting, AudioDriverManager::DEFAULT_MIX_RATE));
#endif
		mix_rate = AudioDriverManager::DEFAULT_MIX_RATE;
	}

	return mix_rate;
}

AudioDriver::SpeakerMode AudioDriver::get_speaker_mode_by_total_channels(int p_channels) const {
	switch (p_channels) {
		case 4:
			return SPEAKER_SURROUND_31;
		case 6:
			return SPEAKER_SURROUND_51;
		case 8:
			return SPEAKER_SURROUND_71;
	}

	// Default to STEREO
	return SPEAKER_MODE_STEREO;
}

int AudioDriver::get_total_channels_by_speaker_mode(AudioDriver::SpeakerMode p_mode) const {
	switch (p_mode) {
		case SPEAKER_MODE_STEREO:
			return 2;
		case SPEAKER_SURROUND_31:
			return 4;
		case SPEAKER_SURROUND_51:
			return 6;
		case SPEAKER_SURROUND_71:
			return 8;
	}

	ERR_FAIL_V(2);
}

PackedStringArray AudioDriver::get_output_device_list() {
	PackedStringArray list;

	list.push_back("Default");

	return list;
}

String AudioDriver::get_output_device() {
	return "Default";
}

PackedStringArray AudioDriver::get_input_device_list() {
	PackedStringArray list;

	list.push_back("Default");

	return list;
}

AudioDriverDummy AudioDriverManager::dummy_driver;
AudioDriver *AudioDriverManager::drivers[MAX_DRIVERS] = {
	&AudioDriverManager::dummy_driver,
};
int AudioDriverManager::driver_count = 1;

void AudioDriverManager::add_driver(AudioDriver *p_driver) {
	ERR_FAIL_COND(driver_count >= MAX_DRIVERS);
	drivers[driver_count - 1] = p_driver;

	// Last driver is always our dummy driver
	drivers[driver_count++] = &AudioDriverManager::dummy_driver;
}

int AudioDriverManager::get_driver_count() {
	return driver_count;
}

void AudioDriverManager::initialize(int p_driver) {
	GLOBAL_DEF_RST("audio/driver/enable_input", false);
	GLOBAL_DEF_RST(PropertyInfo(Variant::INT, "audio/driver/mix_rate", PROPERTY_HINT_RANGE, "11025,192000,1,or_greater,suffix:Hz"), DEFAULT_MIX_RATE);
	GLOBAL_DEF_RST(PropertyInfo(Variant::INT, "audio/driver/mix_rate.web", PROPERTY_HINT_RANGE, "0,192000,1,or_greater,suffix:Hz"), 0); // Safer default output_latency for web (use browser default).

	int failed_driver = -1;

	// Check if there is a selected driver
	if (p_driver >= 0 && p_driver < driver_count) {
		if (drivers[p_driver]->init() == OK) {
			drivers[p_driver]->set_singleton();
			return;
		} else {
			failed_driver = p_driver;
		}
	}

	// No selected driver, try them all in order
	for (int i = 0; i < driver_count; i++) {
		// Don't re-init the driver if it failed above
		if (i == failed_driver) {
			continue;
		}

		if (drivers[i]->init() == OK) {
			drivers[i]->set_singleton();
			break;
		}
	}

	if (driver_count > 1 && String(AudioDriver::get_singleton()->get_name()) == "Dummy") {
		WARN_PRINT("All audio drivers failed, falling back to the dummy driver.");
	}
}

AudioDriver *AudioDriverManager::get_driver(int p_driver) {
	ERR_FAIL_INDEX_V(p_driver, driver_count, nullptr);
	return drivers[p_driver];
}

//////////////////////////////////////////////
//////////////////////////////////////////////
//////////////////////////////////////////////
//////////////////////////////////////////////

void AudioServer::_driver_process(int p_frames, int32_t *p_buffer) {
	mix_count++;
	int todo = p_frames;

#ifdef DEBUG_ENABLED
	uint64_t prof_ticks = OS::get_singleton()->get_ticks_usec();
#endif

	if (channel_count != get_channel_count()) {
		// Amount of channels changed due to a output_device change
		// reinitialize the buses channels and buffers
		init_channels_and_buffers();
	}

	ERR_FAIL_COND_MSG(buses.is_empty() && todo, "AudioServer bus count is less than 1.");
	while (todo) {
		if (to_mix == 0) {
			_mix_step();
		}

		int to_copy = MIN(to_mix, todo);

		Bus *master = buses[0];

		int from = buffer_size - to_mix;
		int from_buf = p_frames - todo;

		//master master, send to output
		int cs = master->channels.size();

		// Take away 1 from the stride, as we are manually incrementing by 1 for stereo.
		uintptr_t stride_minus_one = (cs * 2) - 1;

		for (int k = 0; k < cs; k++) {
			// The destination start for data will be the same in all cases.
			int32_t *dest = &p_buffer[from_buf * (cs * 2) + (k * 2)];

			if (master->channels[k].active) {
				const AudioFrame *buf = master->channels[k].buffer.ptr();

				for (int j = 0; j < to_copy; j++) {
					float l = CLAMP(buf[from + j].left, -1.0, 1.0);
					int32_t vl = l * ((1 << 20) - 1);
					int32_t vl2 = (vl < 0 ? -1 : 1) * (ABS(vl) << 11);
					*dest = vl2;
					dest++;

					float r = CLAMP(buf[from + j].right, -1.0, 1.0);
					int32_t vr = r * ((1 << 20) - 1);
					int32_t vr2 = (vr < 0 ? -1 : 1) * (ABS(vr) << 11);
					*dest = vr2;
					dest += stride_minus_one;
				}

			} else {
				// Bizarrely, profiling indicates that detecting the common case of cs == 1,
				// k == 0, and using memset is SLOWER than setting them individually.
				// Perhaps it gets optimized to a faster instruction than memset.
				for (int j = 0; j < to_copy; j++) {
					*dest = 0;
					dest++;
					*dest = 0;
					dest += stride_minus_one;
				}
			}
		}

		todo -= to_copy;
		to_mix -= to_copy;
	}

#ifdef DEBUG_ENABLED
	prof_time.add(OS::get_singleton()->get_ticks_usec() - prof_ticks);
#endif
}

void AudioServer::_mix_step() {
	bool solo_mode = false;

	for (int i = 0; i < buses.size(); i++) {
		Bus *bus = buses[i];
		bus->index_cache = i; //might be moved around by editor, so..
		for (int k = 0; k < bus->channels.size(); k++) {
			bus->channels.write[k].used = false;
		}

		if (bus->solo) {
			//solo chain
			solo_mode = true;
			bus->soloed = true;
			do {
				if (bus != buses[0]) {
					//everything has a send save for master bus
					if (!bus_map.has(bus->send)) {
						bus = buses[0]; //send to master
					} else {
						int prev_index_cache = bus->index_cache;
						bus = bus_map[bus->send];
						if (prev_index_cache >= bus->index_cache) { //invalid, send to master
							bus = buses[0];
						}
					}

					bus->soloed = true;
				} else {
					bus = nullptr;
				}

			} while (bus);
		} else {
			bus->soloed = false;
		}
	}
	for (CallbackItem *ci : mix_callback_list) {
		ci->callback(ci->userdata);
	}

	for (AudioStreamPlaybackListNode *playback : playback_list) {
		// Paused streams are no-ops. Don't even mix audio from the stream playback.
		if (playback->state.load() == AudioStreamPlaybackListNode::PAUSED) {
			continue;
		}

		bool fading_out = playback->state.load() == AudioStreamPlaybackListNode::FADE_OUT_TO_DELETION || playback->state.load() == AudioStreamPlaybackListNode::FADE_OUT_TO_PAUSE;

		AudioFrame *buf = mix_buffer.ptrw();

		// Copy the lookeahead buffer into the mix buffer.
		for (int i = 0; i < LOOKAHEAD_BUFFER_SIZE; i++) {
			buf[i] = playback->lookahead[i];
		}

		// Mix the audio stream
		unsigned int mixed_frames = playback->stream_playback->mix(&buf[LOOKAHEAD_BUFFER_SIZE], playback->pitch_scale.get(), buffer_size);

		if (tag_used_audio_streams && playback->stream_playback->is_playing()) {
			playback->stream_playback->tag_used_streams();
		}

		if (mixed_frames != buffer_size) {
			// We know we have at least the size of our lookahead buffer for fade-out purposes.

			float fadeout_base = 0.94;
			float fadeout_coefficient = 1;
			static_assert(LOOKAHEAD_BUFFER_SIZE == 64, "Update fadeout_base and comment here if you change LOOKAHEAD_BUFFER_SIZE.");
			// 0.94 ^ 64 = 0.01906. There might still be a pop but it'll be way better than if we didn't do this.
			for (unsigned int idx = mixed_frames; idx < buffer_size; idx++) {
				fadeout_coefficient *= fadeout_base;
				buf[idx] *= fadeout_coefficient;
			}
			AudioStreamPlaybackListNode::PlaybackState new_state;
			new_state = AudioStreamPlaybackListNode::AWAITING_DELETION;
			playback->state.store(new_state);
		} else {
			// Move the last little bit of what we just mixed into our lookahead buffer.
			for (int i = 0; i < LOOKAHEAD_BUFFER_SIZE; i++) {
				playback->lookahead[i] = buf[buffer_size + i];
			}
		}

		AudioStreamPlaybackBusDetails *ptr = playback->bus_details.load();
		ERR_FAIL_NULL(ptr);
		// By putting null into the bus details pointers, we're taking ownership of their memory for the duration of this mix.
		AudioStreamPlaybackBusDetails bus_details = *ptr;

		// Mix to any active buses.
		for (int idx = 0; idx < MAX_BUSES_PER_PLAYBACK; idx++) {
			if (!bus_details.bus_active[idx]) {
				continue;
			}
			int bus_idx = thread_find_bus_index(bus_details.bus[idx]);

			int prev_bus_idx = -1;
			for (int search_idx = 0; search_idx < MAX_BUSES_PER_PLAYBACK; search_idx++) {
				if (!playback->prev_bus_details->bus_active[search_idx]) {
					continue;
				}
				if (playback->prev_bus_details->bus[search_idx].hash() == bus_details.bus[idx].hash()) {
					prev_bus_idx = search_idx;
				}
			}

			for (int channel_idx = 0; channel_idx < channel_count; channel_idx++) {
				AudioFrame *channel_buf = thread_get_channel_mix_buffer(bus_idx, channel_idx);
				if (fading_out) {
					bus_details.volume[idx][channel_idx] = AudioFrame(0, 0);
				}
				AudioFrame channel_vol = bus_details.volume[idx][channel_idx];

				AudioFrame prev_channel_vol = AudioFrame(0, 0);
				if (prev_bus_idx != -1) {
					prev_channel_vol = playback->prev_bus_details->volume[prev_bus_idx][channel_idx];
				}
				_mix_step_for_channel(channel_buf, buf, prev_channel_vol, channel_vol, playback->attenuation_filter_cutoff_hz.get(), playback->highshelf_gain.get(), &playback->filter_process[channel_idx * 2], &playback->filter_process[channel_idx * 2 + 1]);
			}
		}

		// Now go through and fade-out any buses that were being played to previously that we missed by going through current data.
		for (int idx = 0; idx < MAX_BUSES_PER_PLAYBACK; idx++) {
			if (!playback->prev_bus_details->bus_active[idx]) {
				continue;
			}
			int bus_idx = thread_find_bus_index(playback->prev_bus_details->bus[idx]);

			int current_bus_idx = -1;
			for (int search_idx = 0; search_idx < MAX_BUSES_PER_PLAYBACK; search_idx++) {
				if (bus_details.bus[search_idx] == playback->prev_bus_details->bus[idx]) {
					current_bus_idx = search_idx;
				}
			}
			if (current_bus_idx != -1) {
				// If we found a corresponding bus in the current bus assignments, we've already mixed to this bus.
				continue;
			}

			for (int channel_idx = 0; channel_idx < channel_count; channel_idx++) {
				AudioFrame *channel_buf = thread_get_channel_mix_buffer(bus_idx, channel_idx);
				AudioFrame prev_channel_vol = playback->prev_bus_details->volume[idx][channel_idx];
				// Fade out to silence
				_mix_step_for_channel(channel_buf, buf, prev_channel_vol, AudioFrame(0, 0), playback->attenuation_filter_cutoff_hz.get(), playback->highshelf_gain.get(), &playback->filter_process[channel_idx * 2], &playback->filter_process[channel_idx * 2 + 1]);
			}
		}

		// Copy the bus details we mixed with to the previous bus details to maintain volume ramps.
		std::copy(std::begin(bus_details.bus_active), std::end(bus_details.bus_active), std::begin(playback->prev_bus_details->bus_active));
		std::copy(std::begin(bus_details.bus), std::end(bus_details.bus), std::begin(playback->prev_bus_details->bus));
		for (int bus_idx = 0; bus_idx < MAX_BUSES_PER_PLAYBACK; bus_idx++) {
			std::copy(std::begin(bus_details.volume[bus_idx]), std::end(bus_details.volume[bus_idx]), std::begin(playback->prev_bus_details->volume[bus_idx]));
		}

		switch (playback->state.load()) {
			case AudioStreamPlaybackListNode::AWAITING_DELETION:
			case AudioStreamPlaybackListNode::FADE_OUT_TO_DELETION:
				playback_list.erase(playback, [](AudioStreamPlaybackListNode *p) {
					delete p->prev_bus_details;
					delete p->bus_details;
					p->stream_playback.unref();
					delete p;
				});
				break;
			case AudioStreamPlaybackListNode::FADE_OUT_TO_PAUSE: {
				// Pause the stream.
				AudioStreamPlaybackListNode::PlaybackState old_state, new_state;
				do {
					old_state = playback->state.load();
					new_state = AudioStreamPlaybackListNode::PAUSED;
				} while (!playback->state.compare_exchange_strong(/* expected= */ old_state, new_state));
			} break;
			case AudioStreamPlaybackListNode::PLAYING:
			case AudioStreamPlaybackListNode::PAUSED:
				// No-op!
				break;
		}
	}

	for (int i = buses.size() - 1; i >= 0; i--) {
		//go bus by bus
		Bus *bus = buses[i];

		for (int k = 0; k < bus->channels.size(); k++) {
			if (bus->channels[k].active && !bus->channels[k].used) {
				//buffer was not used, but it's still active, so it must be cleaned
				AudioFrame *buf = bus->channels.write[k].buffer.ptrw();

				for (uint32_t j = 0; j < buffer_size; j++) {
					buf[j] = AudioFrame(0, 0);
				}
			}
		}

		//process effects
		if (!bus->bypass) {
			for (int j = 0; j < bus->effects.size(); j++) {
				if (!bus->effects[j].enabled) {
					continue;
				}

#ifdef DEBUG_ENABLED
				uint64_t ticks = OS::get_singleton()->get_ticks_usec();
#endif

				for (int k = 0; k < bus->channels.size(); k++) {
					if (!(bus->channels[k].active || bus->channels[k].effect_instances[j]->process_silence())) {
						continue;
					}
					bus->channels.write[k].effect_instances.write[j]->process(bus->channels[k].buffer.ptr(), temp_buffer.write[k].ptrw(), buffer_size);
				}

				//swap buffers, so internal buffer always has the right data
				for (int k = 0; k < bus->channels.size(); k++) {
					if (!(buses[i]->channels[k].active || bus->channels[k].effect_instances[j]->process_silence())) {
						continue;
					}
					SWAP(bus->channels.write[k].buffer, temp_buffer.write[k]);
				}

#ifdef DEBUG_ENABLED
				bus->effects.write[j].prof_time += OS::get_singleton()->get_ticks_usec() - ticks;
#endif
			}
		}

		//process send

		Bus *send = nullptr;

		if (i > 0) {
			//everything has a send save for master bus
			if (!bus_map.has(bus->send)) {
				send = buses[0];
			} else {
				send = bus_map[bus->send];
				if (send->index_cache >= bus->index_cache) { //invalid, send to master
					send = buses[0];
				}
			}
		}

		for (int k = 0; k < bus->channels.size(); k++) {
			if (!bus->channels[k].active) {
				bus->channels.write[k].peak_volume = AudioFrame(AUDIO_MIN_PEAK_DB, AUDIO_MIN_PEAK_DB);
				continue;
			}

			AudioFrame *buf = bus->channels.write[k].buffer.ptrw();

			AudioFrame peak = AudioFrame(0, 0);

			float volume = Math::db_to_linear(bus->volume_db);

			if (solo_mode) {
				if (!bus->soloed) {
					volume = 0.0;
				}
			} else {
				if (bus->mute) {
					volume = 0.0;
				}
			}

			//apply volume and compute peak
			for (uint32_t j = 0; j < buffer_size; j++) {
				buf[j] *= volume;

				float l = ABS(buf[j].left);
				if (l > peak.left) {
					peak.left = l;
				}
				float r = ABS(buf[j].right);
				if (r > peak.right) {
					peak.right = r;
				}
			}

			bus->channels.write[k].peak_volume = AudioFrame(Math::linear_to_db(peak.left + AUDIO_PEAK_OFFSET), Math::linear_to_db(peak.right + AUDIO_PEAK_OFFSET));

			if (!bus->channels[k].used) {
				//see if any audio is contained, because channel was not used

				if (MAX(peak.right, peak.left) > Math::db_to_linear(channel_disable_threshold_db)) {
					bus->channels.write[k].last_mix_with_audio = mix_frames;
				} else if (mix_frames - bus->channels[k].last_mix_with_audio > channel_disable_frames) {
					bus->channels.write[k].active = false;
					continue; //went inactive, don't mix.
				}
			}

			if (send) {
				//if not master bus, send
				AudioFrame *target_buf = thread_get_channel_mix_buffer(send->index_cache, k);

				for (uint32_t j = 0; j < buffer_size; j++) {
					target_buf[j] += buf[j];
				}
			}
		}
	}

	mix_frames += buffer_size;
	to_mix = buffer_size;
}

void AudioServer::_mix_step_for_channel(AudioFrame *p_out_buf, AudioFrame *p_source_buf, AudioFrame p_vol_start, AudioFrame p_vol_final, float p_attenuation_filter_cutoff_hz, float p_highshelf_gain, AudioFilterSW::Processor *p_processor_l, AudioFilterSW::Processor *p_processor_r) {
	if (p_highshelf_gain != 0) {
		AudioFilterSW filter;
		filter.set_mode(AudioFilterSW::HIGHSHELF);
		filter.set_sampling_rate(AudioServer::get_singleton()->get_mix_rate());
		filter.set_cutoff(p_attenuation_filter_cutoff_hz);
		filter.set_resonance(1);
		filter.set_stages(1);
		filter.set_gain(p_highshelf_gain);

		ERR_FAIL_NULL(p_processor_l);
		ERR_FAIL_NULL(p_processor_r);

		bool is_just_started = p_vol_start.left == 0 && p_vol_start.right == 0;
		p_processor_l->set_filter(&filter, /* clear_history= */ is_just_started);
		p_processor_l->update_coeffs(buffer_size);
		p_processor_r->set_filter(&filter, /* clear_history= */ is_just_started);
		p_processor_r->update_coeffs(buffer_size);

		for (unsigned int frame_idx = 0; frame_idx < buffer_size; frame_idx++) {
			// Make this buffer size invariant if buffer_size ever becomes a project setting.
			float lerp_param = (float)frame_idx / buffer_size;
			AudioFrame vol = p_vol_final * lerp_param + (1 - lerp_param) * p_vol_start;
			AudioFrame mixed = vol * p_source_buf[frame_idx];
			p_processor_l->process_one_interp(mixed.left);
			p_processor_r->process_one_interp(mixed.right);
			p_out_buf[frame_idx] += mixed;
		}

	} else {
		for (unsigned int frame_idx = 0; frame_idx < buffer_size; frame_idx++) {
			// Make this buffer size invariant if buffer_size ever becomes a project setting.
			float lerp_param = (float)frame_idx / buffer_size;
			p_out_buf[frame_idx] += (p_vol_final * lerp_param + (1 - lerp_param) * p_vol_start) * p_source_buf[frame_idx];
		}
	}
}

AudioServer::AudioStreamPlaybackListNode *AudioServer::_find_playback_list_node(Ref<AudioStreamPlayback> p_playback) {
	for (AudioStreamPlaybackListNode *playback_list_node : playback_list) {
		if (playback_list_node->stream_playback == p_playback) {
			return playback_list_node;
		}
	}
	return nullptr;
}

bool AudioServer::thread_has_channel_mix_buffer(int p_bus, int p_buffer) const {
	if (p_bus < 0 || p_bus >= buses.size()) {
		return false;
	}
	if (p_buffer < 0 || p_buffer >= buses[p_bus]->channels.size()) {
		return false;
	}
	return true;
}

AudioFrame *AudioServer::thread_get_channel_mix_buffer(int p_bus, int p_buffer) {
	ERR_FAIL_INDEX_V(p_bus, buses.size(), nullptr);
	ERR_FAIL_INDEX_V(p_buffer, buses[p_bus]->channels.size(), nullptr);

	AudioFrame *data = buses.write[p_bus]->channels.write[p_buffer].buffer.ptrw();

	if (!buses[p_bus]->channels[p_buffer].used) {
		buses.write[p_bus]->channels.write[p_buffer].used = true;
		buses.write[p_bus]->channels.write[p_buffer].active = true;
		buses.write[p_bus]->channels.write[p_buffer].last_mix_with_audio = mix_frames;
		for (uint32_t i = 0; i < buffer_size; i++) {
			data[i] = AudioFrame(0, 0);
		}
	}

	return data;
}

int AudioServer::thread_get_mix_buffer_size() const {
	return buffer_size;
}

int AudioServer::thread_find_bus_index(const StringName &p_name) {
	if (bus_map.has(p_name)) {
		return bus_map[p_name]->index_cache;
	} else {
		return 0;
	}
}

void AudioServer::set_bus_count(int p_count) {
	ERR_FAIL_COND(p_count < 1);
	ERR_FAIL_INDEX(p_count, 256);

	MARK_EDITED

	lock();
	int cb = buses.size();

	if (p_count < buses.size()) {
		for (int i = p_count; i < buses.size(); i++) {
			bus_map.erase(buses[i]->name);
			memdelete(buses[i]);
		}
	}

	buses.resize(p_count);

	for (int i = cb; i < buses.size(); i++) {
		String attempt = "New Bus";
		int attempts = 1;
		while (true) {
			bool name_free = true;
			for (int j = 0; j < i; j++) {
				if (buses[j]->name == attempt) {
					name_free = false;
					break;
				}
			}

			if (!name_free) {
				attempts++;
				attempt = "New Bus " + itos(attempts);
			} else {
				break;
			}
		}

		buses.write[i] = memnew(Bus);
		buses.write[i]->channels.resize(channel_count);
		for (int j = 0; j < channel_count; j++) {
			buses.write[i]->channels.write[j].buffer.resize(buffer_size);
		}
		buses[i]->name = attempt;
		buses[i]->solo = false;
		buses[i]->mute = false;
		buses[i]->bypass = false;
		buses[i]->volume_db = 0;
		if (i > 0) {
			buses[i]->send = SceneStringNames::get_singleton()->Master;
		}

		bus_map[attempt] = buses[i];
	}

	unlock();

	emit_signal(SNAME("bus_layout_changed"));
}

void AudioServer::remove_bus(int p_index) {
	ERR_FAIL_INDEX(p_index, buses.size());
	ERR_FAIL_COND(p_index == 0);

	MARK_EDITED

	lock();
	bus_map.erase(buses[p_index]->name);
	memdelete(buses[p_index]);
	buses.remove_at(p_index);
	unlock();

	emit_signal(SNAME("bus_layout_changed"));
}

void AudioServer::add_bus(int p_at_pos) {
	MARK_EDITED

	if (p_at_pos >= buses.size()) {
		p_at_pos = -1;
	} else if (p_at_pos == 0) {
		if (buses.size() > 1) {
			p_at_pos = 1;
		} else {
			p_at_pos = -1;
		}
	}

	String attempt = "New Bus";
	int attempts = 1;
	while (true) {
		bool name_free = true;
		for (int j = 0; j < buses.size(); j++) {
			if (buses[j]->name == attempt) {
				name_free = false;
				break;
			}
		}

		if (!name_free) {
			attempts++;
			attempt = "New Bus " + itos(attempts);
		} else {
			break;
		}
	}

	Bus *bus = memnew(Bus);
	bus->channels.resize(channel_count);
	for (int j = 0; j < channel_count; j++) {
		bus->channels.write[j].buffer.resize(buffer_size);
	}
	bus->name = attempt;
	bus->solo = false;
	bus->mute = false;
	bus->bypass = false;
	bus->volume_db = 0;

	bus_map[attempt] = bus;

	if (p_at_pos == -1) {
		buses.push_back(bus);
	} else {
		buses.insert(p_at_pos, bus);
	}

	emit_signal(SNAME("bus_layout_changed"));
}

void AudioServer::move_bus(int p_bus, int p_to_pos) {
	ERR_FAIL_COND(p_bus < 1 || p_bus >= buses.size());
	ERR_FAIL_COND(p_to_pos != -1 && (p_to_pos < 1 || p_to_pos > buses.size()));

	MARK_EDITED

	if (p_bus == p_to_pos) {
		return;
	}

	Bus *bus = buses[p_bus];
	buses.remove_at(p_bus);

	if (p_to_pos == -1) {
		buses.push_back(bus);
	} else if (p_to_pos < p_bus) {
		buses.insert(p_to_pos, bus);
	} else {
		buses.insert(p_to_pos - 1, bus);
	}

	emit_signal(SNAME("bus_layout_changed"));
}

int AudioServer::get_bus_count() const {
	return buses.size();
}

void AudioServer::set_bus_name(int p_bus, const String &p_name) {
	ERR_FAIL_INDEX(p_bus, buses.size());
	if (p_bus == 0 && p_name != "Master") {
		return; // Bus 0 is always "Master".
	}

	MARK_EDITED

	lock();

	StringName old_name = buses[p_bus]->name;

	if (old_name == p_name) {
		unlock();
		return;
	}

	String attempt = p_name;
	int attempts = 1;

	while (true) {
		bool name_free = true;
		for (int i = 0; i < buses.size(); i++) {
			if (buses[i]->name == attempt) {
				name_free = false;
				break;
			}
		}

		if (name_free) {
			break;
		}

		attempts++;
		attempt = p_name + " " + itos(attempts);
	}
	bus_map.erase(old_name);
	buses[p_bus]->name = attempt;
	bus_map[attempt] = buses[p_bus];
	unlock();

	emit_signal(SNAME("bus_renamed"), p_bus, old_name, attempt);
}

String AudioServer::get_bus_name(int p_bus) const {
	ERR_FAIL_INDEX_V(p_bus, buses.size(), String());
	return buses[p_bus]->name;
}

int AudioServer::get_bus_index(const StringName &p_bus_name) const {
	for (int i = 0; i < buses.size(); ++i) {
		if (buses[i]->name == p_bus_name) {
			return i;
		}
	}
	return -1;
}

void AudioServer::set_bus_volume_db(int p_bus, float p_volume_db) {
	ERR_FAIL_INDEX(p_bus, buses.size());

	MARK_EDITED

	buses[p_bus]->volume_db = p_volume_db;
}

float AudioServer::get_bus_volume_db(int p_bus) const {
	ERR_FAIL_INDEX_V(p_bus, buses.size(), 0);
	return buses[p_bus]->volume_db;
}

int AudioServer::get_bus_channels(int p_bus) const {
	ERR_FAIL_INDEX_V(p_bus, buses.size(), 0);
	return buses[p_bus]->channels.size();
}

void AudioServer::set_bus_send(int p_bus, const StringName &p_send) {
	ERR_FAIL_INDEX(p_bus, buses.size());

	MARK_EDITED

	buses[p_bus]->send = p_send;
}

StringName AudioServer::get_bus_send(int p_bus) const {
	ERR_FAIL_INDEX_V(p_bus, buses.size(), StringName());
	return buses[p_bus]->send;
}

void AudioServer::set_bus_solo(int p_bus, bool p_enable) {
	ERR_FAIL_INDEX(p_bus, buses.size());

	MARK_EDITED

	buses[p_bus]->solo = p_enable;
}

bool AudioServer::is_bus_solo(int p_bus) const {
	ERR_FAIL_INDEX_V(p_bus, buses.size(), false);

	return buses[p_bus]->solo;
}

void AudioServer::set_bus_mute(int p_bus, bool p_enable) {
	ERR_FAIL_INDEX(p_bus, buses.size());

	MARK_EDITED

	buses[p_bus]->mute = p_enable;
}

bool AudioServer::is_bus_mute(int p_bus) const {
	ERR_FAIL_INDEX_V(p_bus, buses.size(), false);

	return buses[p_bus]->mute;
}

void AudioServer::set_bus_bypass_effects(int p_bus, bool p_enable) {
	ERR_FAIL_INDEX(p_bus, buses.size());

	MARK_EDITED

	buses[p_bus]->bypass = p_enable;
}

bool AudioServer::is_bus_bypassing_effects(int p_bus) const {
	ERR_FAIL_INDEX_V(p_bus, buses.size(), false);

	return buses[p_bus]->bypass;
}

void AudioServer::_update_bus_effects(int p_bus) {
	for (int i = 0; i < buses[p_bus]->channels.size(); i++) {
		buses.write[p_bus]->channels.write[i].effect_instances.resize(buses[p_bus]->effects.size());
		for (int j = 0; j < buses[p_bus]->effects.size(); j++) {
			Ref<AudioEffectInstance> fx = buses.write[p_bus]->effects.write[j].effect->instantiate();
			if (Object::cast_to<AudioEffectCompressorInstance>(*fx)) {
				Object::cast_to<AudioEffectCompressorInstance>(*fx)->set_current_channel(i);
			}
			buses.write[p_bus]->channels.write[i].effect_instances.write[j] = fx;
		}
	}
}

void AudioServer::add_bus_effect(int p_bus, const Ref<AudioEffect> &p_effect, int p_at_pos) {
	ERR_FAIL_COND(p_effect.is_null());
	ERR_FAIL_INDEX(p_bus, buses.size());

	MARK_EDITED

	lock();

	Bus::Effect fx;
	fx.effect = p_effect;
	//fx.instance=p_effect->instantiate();
	fx.enabled = true;
#ifdef DEBUG_ENABLED
	fx.prof_time = 0;
#endif

	if (p_at_pos >= buses[p_bus]->effects.size() || p_at_pos < 0) {
		buses[p_bus]->effects.push_back(fx);
	} else {
		buses[p_bus]->effects.insert(p_at_pos, fx);
	}

	_update_bus_effects(p_bus);

	unlock();
}

void AudioServer::remove_bus_effect(int p_bus, int p_effect) {
	ERR_FAIL_INDEX(p_bus, buses.size());

	MARK_EDITED

	lock();

	buses[p_bus]->effects.remove_at(p_effect);
	_update_bus_effects(p_bus);

	unlock();
}

int AudioServer::get_bus_effect_count(int p_bus) {
	ERR_FAIL_INDEX_V(p_bus, buses.size(), 0);

	return buses[p_bus]->effects.size();
}

Ref<AudioEffectInstance> AudioServer::get_bus_effect_instance(int p_bus, int p_effect, int p_channel) {
	ERR_FAIL_INDEX_V(p_bus, buses.size(), Ref<AudioEffectInstance>());
	ERR_FAIL_INDEX_V(p_effect, buses[p_bus]->effects.size(), Ref<AudioEffectInstance>());
	ERR_FAIL_INDEX_V(p_channel, buses[p_bus]->channels.size(), Ref<AudioEffectInstance>());

	return buses[p_bus]->channels[p_channel].effect_instances[p_effect];
}

Ref<AudioEffect> AudioServer::get_bus_effect(int p_bus, int p_effect) {
	ERR_FAIL_INDEX_V(p_bus, buses.size(), Ref<AudioEffect>());
	ERR_FAIL_INDEX_V(p_effect, buses[p_bus]->effects.size(), Ref<AudioEffect>());

	return buses[p_bus]->effects[p_effect].effect;
}

void AudioServer::swap_bus_effects(int p_bus, int p_effect, int p_by_effect) {
	ERR_FAIL_INDEX(p_bus, buses.size());
	ERR_FAIL_INDEX(p_effect, buses[p_bus]->effects.size());
	ERR_FAIL_INDEX(p_by_effect, buses[p_bus]->effects.size());

	MARK_EDITED

	lock();
	SWAP(buses.write[p_bus]->effects.write[p_effect], buses.write[p_bus]->effects.write[p_by_effect]);
	_update_bus_effects(p_bus);
	unlock();
}

void AudioServer::set_bus_effect_enabled(int p_bus, int p_effect, bool p_enabled) {
	ERR_FAIL_INDEX(p_bus, buses.size());
	ERR_FAIL_INDEX(p_effect, buses[p_bus]->effects.size());

	MARK_EDITED

	buses.write[p_bus]->effects.write[p_effect].enabled = p_enabled;
}

bool AudioServer::is_bus_effect_enabled(int p_bus, int p_effect) const {
	ERR_FAIL_INDEX_V(p_bus, buses.size(), false);
	ERR_FAIL_INDEX_V(p_effect, buses[p_bus]->effects.size(), false);
	return buses[p_bus]->effects[p_effect].enabled;
}

float AudioServer::get_bus_peak_volume_left_db(int p_bus, int p_channel) const {
	ERR_FAIL_INDEX_V(p_bus, buses.size(), 0);
	ERR_FAIL_INDEX_V(p_channel, buses[p_bus]->channels.size(), 0);

	return buses[p_bus]->channels[p_channel].peak_volume.left;
}

float AudioServer::get_bus_peak_volume_right_db(int p_bus, int p_channel) const {
	ERR_FAIL_INDEX_V(p_bus, buses.size(), 0);
	ERR_FAIL_INDEX_V(p_channel, buses[p_bus]->channels.size(), 0);

	return buses[p_bus]->channels[p_channel].peak_volume.right;
}

bool AudioServer::is_bus_channel_active(int p_bus, int p_channel) const {
	ERR_FAIL_INDEX_V(p_bus, buses.size(), false);
	ERR_FAIL_INDEX_V(p_channel, buses[p_bus]->channels.size(), false);

	return buses[p_bus]->channels[p_channel].active;
}

void AudioServer::set_playback_speed_scale(float p_scale) {
	ERR_FAIL_COND(p_scale <= 0);

	playback_speed_scale = p_scale;
}

float AudioServer::get_playback_speed_scale() const {
	return playback_speed_scale;
}

void AudioServer::start_playback_stream(Ref<AudioStreamPlayback> p_playback, const StringName &p_bus, Vector<AudioFrame> p_volume_db_vector, float p_start_time, float p_pitch_scale) {
	ERR_FAIL_COND(p_playback.is_null());

	HashMap<StringName, Vector<AudioFrame>> map;
	map[p_bus] = p_volume_db_vector;

	start_playback_stream(p_playback, map, p_start_time, p_pitch_scale);
}

void AudioServer::start_playback_stream(Ref<AudioStreamPlayback> p_playback, const HashMap<StringName, Vector<AudioFrame>> &p_bus_volumes, float p_start_time, float p_pitch_scale, float p_highshelf_gain, float p_attenuation_cutoff_hz) {
	ERR_FAIL_COND(p_playback.is_null());

	AudioStreamPlaybackListNode *playback_node = new AudioStreamPlaybackListNode();
	playback_node->stream_playback = p_playback;
	playback_node->stream_playback->start(p_start_time);

	AudioStreamPlaybackBusDetails *new_bus_details = new AudioStreamPlaybackBusDetails();
	int idx = 0;
	for (KeyValue<StringName, Vector<AudioFrame>> pair : p_bus_volumes) {
		if (pair.value.size() < channel_count || pair.value.size() != MAX_CHANNELS_PER_BUS) {
			delete new_bus_details;
			ERR_FAIL();
		}

		new_bus_details->bus_active[idx] = true;
		new_bus_details->bus[idx] = pair.key;
		for (int channel_idx = 0; channel_idx < MAX_CHANNELS_PER_BUS; channel_idx++) {
			new_bus_details->volume[idx][channel_idx] = pair.value[channel_idx];
		}
		idx++;
	}
	playback_node->bus_details = new_bus_details;
	playback_node->prev_bus_details = new AudioStreamPlaybackBusDetails();

	playback_node->pitch_scale.set(p_pitch_scale);
	playback_node->highshelf_gain.set(p_highshelf_gain);
	playback_node->attenuation_filter_cutoff_hz.set(p_attenuation_cutoff_hz);

	memset(playback_node->prev_bus_details->volume, 0, sizeof(playback_node->prev_bus_details->volume));

	for (AudioFrame &frame : playback_node->lookahead) {
		frame = AudioFrame(0, 0);
	}

	playback_node->state.store(AudioStreamPlaybackListNode::PLAYING);

	playback_list.insert(playback_node);
}

void AudioServer::stop_playback_stream(Ref<AudioStreamPlayback> p_playback) {
	ERR_FAIL_COND(p_playback.is_null());

	AudioStreamPlaybackListNode *playback_node = _find_playback_list_node(p_playback);
	if (!playback_node) {
		return;
	}

	AudioStreamPlaybackListNode::PlaybackState new_state, old_state;
	do {
		old_state = playback_node->state.load();
		if (old_state == AudioStreamPlaybackListNode::AWAITING_DELETION) {
			break; // Don't fade out again.
		}
		new_state = AudioStreamPlaybackListNode::FADE_OUT_TO_DELETION;

	} while (!playback_node->state.compare_exchange_strong(old_state, new_state));
}

void AudioServer::set_playback_bus_exclusive(Ref<AudioStreamPlayback> p_playback, const StringName &p_bus, Vector<AudioFrame> p_volumes) {
	ERR_FAIL_COND(p_volumes.size() != MAX_CHANNELS_PER_BUS);

	HashMap<StringName, Vector<AudioFrame>> map;
	map[p_bus] = p_volumes;

	set_playback_bus_volumes_linear(p_playback, map);
}

void AudioServer::set_playback_bus_volumes_linear(Ref<AudioStreamPlayback> p_playback, const HashMap<StringName, Vector<AudioFrame>> &p_bus_volumes) {
	ERR_FAIL_COND(p_bus_volumes.size() > MAX_BUSES_PER_PLAYBACK);

	AudioStreamPlaybackListNode *playback_node = _find_playback_list_node(p_playback);
	if (!playback_node) {
		return;
	}
	AudioStreamPlaybackBusDetails *old_bus_details, *new_bus_details = new AudioStreamPlaybackBusDetails();

	int idx = 0;
	for (KeyValue<StringName, Vector<AudioFrame>> pair : p_bus_volumes) {
		if (idx >= MAX_BUSES_PER_PLAYBACK) {
			break;
		}
		ERR_FAIL_COND(pair.value.size() < channel_count);
		ERR_FAIL_COND(pair.value.size() != MAX_CHANNELS_PER_BUS);

		new_bus_details->bus_active[idx] = true;
		new_bus_details->bus[idx] = pair.key;
		for (int channel_idx = 0; channel_idx < MAX_CHANNELS_PER_BUS; channel_idx++) {
			new_bus_details->volume[idx][channel_idx] = pair.value[channel_idx];
		}
		idx++;
	}

	do {
		old_bus_details = playback_node->bus_details.load();
	} while (!playback_node->bus_details.compare_exchange_strong(old_bus_details, new_bus_details));

	bus_details_graveyard.insert(old_bus_details);
}

void AudioServer::set_playback_all_bus_volumes_linear(Ref<AudioStreamPlayback> p_playback, Vector<AudioFrame> p_volumes) {
	ERR_FAIL_COND(p_playback.is_null());
	ERR_FAIL_COND(p_volumes.size() != MAX_CHANNELS_PER_BUS);

	HashMap<StringName, Vector<AudioFrame>> map;

	AudioStreamPlaybackListNode *playback_node = _find_playback_list_node(p_playback);
	if (!playback_node) {
		return;
	}
	for (int bus_idx = 0; bus_idx < MAX_BUSES_PER_PLAYBACK; bus_idx++) {
		if (playback_node->bus_details.load()->bus_active[bus_idx]) {
			map[playback_node->bus_details.load()->bus[bus_idx]] = p_volumes;
		}
	}

	set_playback_bus_volumes_linear(p_playback, map);
}

void AudioServer::set_playback_pitch_scale(Ref<AudioStreamPlayback> p_playback, float p_pitch_scale) {
	ERR_FAIL_COND(p_playback.is_null());

	AudioStreamPlaybackListNode *playback_node = _find_playback_list_node(p_playback);
	if (!playback_node) {
		return;
	}

	playback_node->pitch_scale.set(p_pitch_scale);
}

void AudioServer::set_playback_paused(Ref<AudioStreamPlayback> p_playback, bool p_paused) {
	ERR_FAIL_COND(p_playback.is_null());

	AudioStreamPlaybackListNode *playback_node = _find_playback_list_node(p_playback);
	if (!playback_node) {
		return;
	}

	AudioStreamPlaybackListNode::PlaybackState new_state, old_state;
	do {
		old_state = playback_node->state.load();
		new_state = p_paused ? AudioStreamPlaybackListNode::FADE_OUT_TO_PAUSE : AudioStreamPlaybackListNode::PLAYING;
		if (!p_paused && old_state == AudioStreamPlaybackListNode::PLAYING) {
			return; // No-op.
		}
		if (p_paused && (old_state == AudioStreamPlaybackListNode::PAUSED || old_state == AudioStreamPlaybackListNode::FADE_OUT_TO_PAUSE)) {
			return; // No-op.
		}

	} while (!playback_node->state.compare_exchange_strong(old_state, new_state));
}

void AudioServer::set_playback_highshelf_params(Ref<AudioStreamPlayback> p_playback, float p_gain, float p_attenuation_cutoff_hz) {
	ERR_FAIL_COND(p_playback.is_null());

	AudioStreamPlaybackListNode *playback_node = _find_playback_list_node(p_playback);
	if (!playback_node) {
		return;
	}

	playback_node->attenuation_filter_cutoff_hz.set(p_attenuation_cutoff_hz);
	playback_node->highshelf_gain.set(p_gain);
}

bool AudioServer::is_playback_active(Ref<AudioStreamPlayback> p_playback) {
	ERR_FAIL_COND_V(p_playback.is_null(), false);

	AudioStreamPlaybackListNode *playback_node = _find_playback_list_node(p_playback);
	if (!playback_node) {
		return false;
	}

	return playback_node->state.load() == AudioStreamPlaybackListNode::PLAYING;
}

float AudioServer::get_playback_position(Ref<AudioStreamPlayback> p_playback) {
	ERR_FAIL_COND_V(p_playback.is_null(), 0);

	AudioStreamPlaybackListNode *playback_node = _find_playback_list_node(p_playback);
	if (!playback_node) {
		return 0;
	}

	return playback_node->stream_playback->get_playback_position();
}

bool AudioServer::is_playback_paused(Ref<AudioStreamPlayback> p_playback) {
	ERR_FAIL_COND_V(p_playback.is_null(), false);

	AudioStreamPlaybackListNode *playback_node = _find_playback_list_node(p_playback);
	if (!playback_node) {
		return false;
	}

	return playback_node->state.load() == AudioStreamPlaybackListNode::PAUSED || playback_node->state.load() == AudioStreamPlaybackListNode::FADE_OUT_TO_PAUSE;
}

uint64_t AudioServer::get_mix_count() const {
	return mix_count;
}

uint64_t AudioServer::get_mixed_frames() const {
	return mix_frames;
}

void AudioServer::notify_listener_changed() {
	for (CallbackItem *ci : listener_changed_callback_list) {
		ci->callback(ci->userdata);
	}
}

void AudioServer::init_channels_and_buffers() {
	channel_count = get_channel_count();
	temp_buffer.resize(channel_count);
	mix_buffer.resize(buffer_size + LOOKAHEAD_BUFFER_SIZE);

	for (int i = 0; i < temp_buffer.size(); i++) {
		temp_buffer.write[i].resize(buffer_size);
	}

	for (int i = 0; i < buses.size(); i++) {
		buses[i]->channels.resize(channel_count);
		for (int j = 0; j < channel_count; j++) {
			buses.write[i]->channels.write[j].buffer.resize(buffer_size);
		}
		_update_bus_effects(i);
	}
}

void AudioServer::init() {
	channel_disable_threshold_db = GLOBAL_DEF_RST("audio/buses/channel_disable_threshold_db", -60.0);
	channel_disable_frames = float(GLOBAL_DEF_RST(PropertyInfo(Variant::FLOAT, "audio/buses/channel_disable_time", PROPERTY_HINT_RANGE, "0,5,0.01,or_greater"), 2.0)) * get_mix_rate();
	buffer_size = 512; //hardcoded for now

	init_channels_and_buffers();

	mix_count = 0;
	set_bus_count(1);
	set_bus_name(0, "Master");

	if (AudioDriver::get_singleton()) {
		AudioDriver::get_singleton()->start();
	}

#ifdef TOOLS_ENABLED
	set_edited(false); //avoid editors from thinking this was edited
#endif

	GLOBAL_DEF_RST("audio/video/video_delay_compensation_ms", 0);
}

void AudioServer::update() {
#ifdef DEBUG_ENABLED
	if (EngineDebugger::is_profiling("servers")) {
		// Driver time includes server time + effects times
		// Server time includes effects times
		uint64_t driver_time = AudioDriver::get_singleton()->get_profiling_time();
		uint64_t server_time = prof_time.get();

		// Subtract the server time from the driver time
		if (driver_time > server_time) {
			driver_time -= server_time;
		}

		Array values;

		for (int i = buses.size() - 1; i >= 0; i--) {
			Bus *bus = buses[i];
			if (bus->bypass) {
				continue;
			}

			for (int j = 0; j < bus->effects.size(); j++) {
				if (!bus->effects[j].enabled) {
					continue;
				}

				values.push_back(String(bus->name) + bus->effects[j].effect->get_name());
				values.push_back(USEC_TO_SEC(bus->effects[j].prof_time));

				// Subtract the effect time from the driver and server times
				if (driver_time > bus->effects[j].prof_time) {
					driver_time -= bus->effects[j].prof_time;
				}
				if (server_time > bus->effects[j].prof_time) {
					server_time -= bus->effects[j].prof_time;
				}
			}
		}

		values.push_back("audio_server");
		values.push_back(USEC_TO_SEC(server_time));
		values.push_back("audio_driver");
		values.push_back(USEC_TO_SEC(driver_time));

		values.push_front("audio_thread");
		EngineDebugger::profiler_add_frame_data("servers", values);
	}

	// Reset profiling times
	for (int i = buses.size() - 1; i >= 0; i--) {
		Bus *bus = buses[i];
		if (bus->bypass) {
			continue;
		}

		for (int j = 0; j < bus->effects.size(); j++) {
			if (!bus->effects[j].enabled) {
				continue;
			}

			bus->effects.write[j].prof_time = 0;
		}
	}

	AudioDriver::get_singleton()->reset_profiling_time();
	prof_time.set(0);
#endif

	for (CallbackItem *ci : update_callback_list) {
		ci->callback(ci->userdata);
	}
	mix_callback_list.maybe_cleanup();
	update_callback_list.maybe_cleanup();
	listener_changed_callback_list.maybe_cleanup();
	playback_list.maybe_cleanup();
	for (AudioStreamPlaybackBusDetails *bus_details : bus_details_graveyard_frame_old) {
		bus_details_graveyard_frame_old.erase(bus_details, [](AudioStreamPlaybackBusDetails *d) { delete d; });
	}
	for (AudioStreamPlaybackBusDetails *bus_details : bus_details_graveyard) {
		bus_details_graveyard_frame_old.insert(bus_details);
		bus_details_graveyard.erase(bus_details);
	}
	bus_details_graveyard.maybe_cleanup();
	bus_details_graveyard_frame_old.maybe_cleanup();
}

void AudioServer::load_default_bus_layout() {
	String layout_path = GLOBAL_GET("audio/buses/default_bus_layout");

	if (ResourceLoader::exists(layout_path)) {
		Ref<AudioBusLayout> default_layout = ResourceLoader::load(layout_path);
		if (default_layout.is_valid()) {
			set_bus_layout(default_layout);
		}
	}
}

void AudioServer::finish() {
	for (int i = 0; i < AudioDriverManager::get_driver_count(); i++) {
		AudioDriverManager::get_driver(i)->finish();
	}

	for (int i = 0; i < buses.size(); i++) {
		memdelete(buses[i]);
	}

	buses.clear();
}

/* MISC config */

void AudioServer::lock() {
	AudioDriver::get_singleton()->lock();
}

void AudioServer::unlock() {
	AudioDriver::get_singleton()->unlock();
}

AudioServer::SpeakerMode AudioServer::get_speaker_mode() const {
	return (AudioServer::SpeakerMode)AudioDriver::get_singleton()->get_speaker_mode();
}

float AudioServer::get_mix_rate() const {
	return AudioDriver::get_singleton()->get_mix_rate();
}

float AudioServer::read_output_peak_db() const {
	return 0;
}

AudioServer *AudioServer::get_singleton() {
	return singleton;
}

double AudioServer::get_output_latency() const {
	return AudioDriver::get_singleton()->get_latency();
}

double AudioServer::get_time_to_next_mix() const {
	return AudioDriver::get_singleton()->get_time_to_next_mix();
}

double AudioServer::get_time_since_last_mix() const {
	return AudioDriver::get_singleton()->get_time_since_last_mix();
}

AudioServer *AudioServer::singleton = nullptr;

void AudioServer::add_update_callback(AudioCallback p_callback, void *p_userdata) {
	CallbackItem *ci = new CallbackItem();
	ci->callback = p_callback;
	ci->userdata = p_userdata;
	update_callback_list.insert(ci);
}

void AudioServer::remove_update_callback(AudioCallback p_callback, void *p_userdata) {
	for (CallbackItem *ci : update_callback_list) {
		if (ci->callback == p_callback && ci->userdata == p_userdata) {
			update_callback_list.erase(ci, [](CallbackItem *c) { delete c; });
		}
	}
}

void AudioServer::add_mix_callback(AudioCallback p_callback, void *p_userdata) {
	CallbackItem *ci = new CallbackItem();
	ci->callback = p_callback;
	ci->userdata = p_userdata;
	mix_callback_list.insert(ci);
}

void AudioServer::remove_mix_callback(AudioCallback p_callback, void *p_userdata) {
	for (CallbackItem *ci : mix_callback_list) {
		if (ci->callback == p_callback && ci->userdata == p_userdata) {
			mix_callback_list.erase(ci, [](CallbackItem *c) { delete c; });
		}
	}
}

void AudioServer::add_listener_changed_callback(AudioCallback p_callback, void *p_userdata) {
	CallbackItem *ci = new CallbackItem();
	ci->callback = p_callback;
	ci->userdata = p_userdata;
	listener_changed_callback_list.insert(ci);
}

void AudioServer::remove_listener_changed_callback(AudioCallback p_callback, void *p_userdata) {
	for (CallbackItem *ci : listener_changed_callback_list) {
		if (ci->callback == p_callback && ci->userdata == p_userdata) {
			listener_changed_callback_list.erase(ci, [](CallbackItem *c) { delete c; });
		}
	}
}

void AudioServer::set_bus_layout(const Ref<AudioBusLayout> &p_bus_layout) {
	ERR_FAIL_COND(p_bus_layout.is_null() || p_bus_layout->buses.is_empty());

	lock();
	for (int i = 0; i < buses.size(); i++) {
		memdelete(buses[i]);
	}
	buses.resize(p_bus_layout->buses.size());
	bus_map.clear();
	for (int i = 0; i < p_bus_layout->buses.size(); i++) {
		Bus *bus = memnew(Bus);
		if (i == 0) {
			bus->name = SceneStringNames::get_singleton()->Master;
		} else {
			bus->name = p_bus_layout->buses[i].name;
			bus->send = p_bus_layout->buses[i].send;
		}

		bus->solo = p_bus_layout->buses[i].solo;
		bus->mute = p_bus_layout->buses[i].mute;
		bus->bypass = p_bus_layout->buses[i].bypass;
		bus->volume_db = p_bus_layout->buses[i].volume_db;

		for (int j = 0; j < p_bus_layout->buses[i].effects.size(); j++) {
			Ref<AudioEffect> fx = p_bus_layout->buses[i].effects[j].effect;

			if (fx.is_valid()) {
				Bus::Effect bfx;
				bfx.effect = fx;
				bfx.enabled = p_bus_layout->buses[i].effects[j].enabled;
#ifdef DEBUG_ENABLED
				bfx.prof_time = 0;
#endif
				bus->effects.push_back(bfx);
			}
		}

		bus_map[bus->name] = bus;
		buses.write[i] = bus;

		buses[i]->channels.resize(channel_count);
		for (int j = 0; j < channel_count; j++) {
			buses.write[i]->channels.write[j].buffer.resize(buffer_size);
		}
		_update_bus_effects(i);
	}
#ifdef TOOLS_ENABLED
	set_edited(false);
#endif
	unlock();
}

Ref<AudioBusLayout> AudioServer::generate_bus_layout() const {
	Ref<AudioBusLayout> state;
	state.instantiate();

	state->buses.resize(buses.size());

	for (int i = 0; i < buses.size(); i++) {
		state->buses.write[i].name = buses[i]->name;
		state->buses.write[i].send = buses[i]->send;
		state->buses.write[i].mute = buses[i]->mute;
		state->buses.write[i].solo = buses[i]->solo;
		state->buses.write[i].bypass = buses[i]->bypass;
		state->buses.write[i].volume_db = buses[i]->volume_db;
		for (int j = 0; j < buses[i]->effects.size(); j++) {
			AudioBusLayout::Bus::Effect fx;
			fx.effect = buses[i]->effects[j].effect;
			fx.enabled = buses[i]->effects[j].enabled;
			state->buses.write[i].effects.push_back(fx);
		}
	}

	return state;
}

PackedStringArray AudioServer::get_output_device_list() {
	return AudioDriver::get_singleton()->get_output_device_list();
}

String AudioServer::get_output_device() {
	return AudioDriver::get_singleton()->get_output_device();
}

void AudioServer::set_output_device(const String &p_name) {
	AudioDriver::get_singleton()->set_output_device(p_name);
}

PackedStringArray AudioServer::get_input_device_list() {
	return AudioDriver::get_singleton()->get_input_device_list();
}

String AudioServer::get_input_device() {
	return AudioDriver::get_singleton()->get_input_device();
}

void AudioServer::set_input_device(const String &p_name) {
	AudioDriver::get_singleton()->set_input_device(p_name);
}

void AudioServer::set_enable_tagging_used_audio_streams(bool p_enable) {
	tag_used_audio_streams = p_enable;
}

void AudioServer::_bind_methods() {
	ClassDB::bind_method(D_METHOD("set_bus_count", "amount"), &AudioServer::set_bus_count);
	ClassDB::bind_method(D_METHOD("get_bus_count"), &AudioServer::get_bus_count);

	ClassDB::bind_method(D_METHOD("remove_bus", "index"), &AudioServer::remove_bus);
	ClassDB::bind_method(D_METHOD("add_bus", "at_position"), &AudioServer::add_bus, DEFVAL(-1));
	ClassDB::bind_method(D_METHOD("move_bus", "index", "to_index"), &AudioServer::move_bus);

	ClassDB::bind_method(D_METHOD("set_bus_name", "bus_idx", "name"), &AudioServer::set_bus_name);
	ClassDB::bind_method(D_METHOD("get_bus_name", "bus_idx"), &AudioServer::get_bus_name);
	ClassDB::bind_method(D_METHOD("get_bus_index", "bus_name"), &AudioServer::get_bus_index);

	ClassDB::bind_method(D_METHOD("get_bus_channels", "bus_idx"), &AudioServer::get_bus_channels);

	ClassDB::bind_method(D_METHOD("set_bus_volume_db", "bus_idx", "volume_db"), &AudioServer::set_bus_volume_db);
	ClassDB::bind_method(D_METHOD("get_bus_volume_db", "bus_idx"), &AudioServer::get_bus_volume_db);

	ClassDB::bind_method(D_METHOD("set_bus_send", "bus_idx", "send"), &AudioServer::set_bus_send);
	ClassDB::bind_method(D_METHOD("get_bus_send", "bus_idx"), &AudioServer::get_bus_send);

	ClassDB::bind_method(D_METHOD("set_bus_solo", "bus_idx", "enable"), &AudioServer::set_bus_solo);
	ClassDB::bind_method(D_METHOD("is_bus_solo", "bus_idx"), &AudioServer::is_bus_solo);

	ClassDB::bind_method(D_METHOD("set_bus_mute", "bus_idx", "enable"), &AudioServer::set_bus_mute);
	ClassDB::bind_method(D_METHOD("is_bus_mute", "bus_idx"), &AudioServer::is_bus_mute);

	ClassDB::bind_method(D_METHOD("set_bus_bypass_effects", "bus_idx", "enable"), &AudioServer::set_bus_bypass_effects);
	ClassDB::bind_method(D_METHOD("is_bus_bypassing_effects", "bus_idx"), &AudioServer::is_bus_bypassing_effects);

	ClassDB::bind_method(D_METHOD("add_bus_effect", "bus_idx", "effect", "at_position"), &AudioServer::add_bus_effect, DEFVAL(-1));
	ClassDB::bind_method(D_METHOD("remove_bus_effect", "bus_idx", "effect_idx"), &AudioServer::remove_bus_effect);

	ClassDB::bind_method(D_METHOD("get_bus_effect_count", "bus_idx"), &AudioServer::get_bus_effect_count);
	ClassDB::bind_method(D_METHOD("get_bus_effect", "bus_idx", "effect_idx"), &AudioServer::get_bus_effect);
	ClassDB::bind_method(D_METHOD("get_bus_effect_instance", "bus_idx", "effect_idx", "channel"), &AudioServer::get_bus_effect_instance, DEFVAL(0));
	ClassDB::bind_method(D_METHOD("swap_bus_effects", "bus_idx", "effect_idx", "by_effect_idx"), &AudioServer::swap_bus_effects);

	ClassDB::bind_method(D_METHOD("set_bus_effect_enabled", "bus_idx", "effect_idx", "enabled"), &AudioServer::set_bus_effect_enabled);
	ClassDB::bind_method(D_METHOD("is_bus_effect_enabled", "bus_idx", "effect_idx"), &AudioServer::is_bus_effect_enabled);

	ClassDB::bind_method(D_METHOD("get_bus_peak_volume_left_db", "bus_idx", "channel"), &AudioServer::get_bus_peak_volume_left_db);
	ClassDB::bind_method(D_METHOD("get_bus_peak_volume_right_db", "bus_idx", "channel"), &AudioServer::get_bus_peak_volume_right_db);

	ClassDB::bind_method(D_METHOD("set_playback_speed_scale", "scale"), &AudioServer::set_playback_speed_scale);
	ClassDB::bind_method(D_METHOD("get_playback_speed_scale"), &AudioServer::get_playback_speed_scale);

	ClassDB::bind_method(D_METHOD("lock"), &AudioServer::lock);
	ClassDB::bind_method(D_METHOD("unlock"), &AudioServer::unlock);

	ClassDB::bind_method(D_METHOD("get_speaker_mode"), &AudioServer::get_speaker_mode);
	ClassDB::bind_method(D_METHOD("get_mix_rate"), &AudioServer::get_mix_rate);

	ClassDB::bind_method(D_METHOD("get_output_device_list"), &AudioServer::get_output_device_list);
	ClassDB::bind_method(D_METHOD("get_output_device"), &AudioServer::get_output_device);
	ClassDB::bind_method(D_METHOD("set_output_device", "name"), &AudioServer::set_output_device);

	ClassDB::bind_method(D_METHOD("get_time_to_next_mix"), &AudioServer::get_time_to_next_mix);
	ClassDB::bind_method(D_METHOD("get_time_since_last_mix"), &AudioServer::get_time_since_last_mix);
	ClassDB::bind_method(D_METHOD("get_output_latency"), &AudioServer::get_output_latency);

	ClassDB::bind_method(D_METHOD("get_input_device_list"), &AudioServer::get_input_device_list);
	ClassDB::bind_method(D_METHOD("get_input_device"), &AudioServer::get_input_device);
	ClassDB::bind_method(D_METHOD("set_input_device", "name"), &AudioServer::set_input_device);

	ClassDB::bind_method(D_METHOD("set_bus_layout", "bus_layout"), &AudioServer::set_bus_layout);
	ClassDB::bind_method(D_METHOD("generate_bus_layout"), &AudioServer::generate_bus_layout);

	ClassDB::bind_method(D_METHOD("set_enable_tagging_used_audio_streams", "enable"), &AudioServer::set_enable_tagging_used_audio_streams);

	ADD_PROPERTY(PropertyInfo(Variant::INT, "bus_count"), "set_bus_count", "get_bus_count");
	ADD_PROPERTY(PropertyInfo(Variant::STRING, "output_device"), "set_output_device", "get_output_device");
	ADD_PROPERTY(PropertyInfo(Variant::STRING, "input_device"), "set_input_device", "get_input_device");
	// The default value may be set to an empty string by the platform-specific audio driver.
	// Override for class reference generation purposes.
	ADD_PROPERTY_DEFAULT("input_device", "Default");
	ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "playback_speed_scale"), "set_playback_speed_scale", "get_playback_speed_scale");

	ADD_SIGNAL(MethodInfo("bus_layout_changed"));
	ADD_SIGNAL(MethodInfo("bus_renamed", PropertyInfo(Variant::INT, "bus_index"), PropertyInfo(Variant::STRING_NAME, "old_name"), PropertyInfo(Variant::STRING_NAME, "new_name")));

	BIND_ENUM_CONSTANT(SPEAKER_MODE_STEREO);
	BIND_ENUM_CONSTANT(SPEAKER_SURROUND_31);
	BIND_ENUM_CONSTANT(SPEAKER_SURROUND_51);
	BIND_ENUM_CONSTANT(SPEAKER_SURROUND_71);
}

AudioServer::AudioServer() {
	singleton = this;
}

AudioServer::~AudioServer() {
	singleton = nullptr;
}

/////////////////////////////////

bool AudioBusLayout::_set(const StringName &p_name, const Variant &p_value) {
	String s = p_name;
	if (s.begins_with("bus/")) {
		int index = s.get_slice("/", 1).to_int();
		if (buses.size() <= index) {
			buses.resize(index + 1);
		}

		Bus &bus = buses.write[index];

		String what = s.get_slice("/", 2);

		if (what == "name") {
			bus.name = p_value;
		} else if (what == "solo") {
			bus.solo = p_value;
		} else if (what == "mute") {
			bus.mute = p_value;
		} else if (what == "bypass_fx") {
			bus.bypass = p_value;
		} else if (what == "volume_db") {
			bus.volume_db = p_value;
		} else if (what == "send") {
			bus.send = p_value;
		} else if (what == "effect") {
			int which = s.get_slice("/", 3).to_int();
			if (bus.effects.size() <= which) {
				bus.effects.resize(which + 1);
			}

			Bus::Effect &fx = bus.effects.write[which];

			String fxwhat = s.get_slice("/", 4);
			if (fxwhat == "effect") {
				fx.effect = p_value;
			} else if (fxwhat == "enabled") {
				fx.enabled = p_value;
			} else {
				return false;
			}

			return true;
		} else {
			return false;
		}

		return true;
	}

	return false;
}

bool AudioBusLayout::_get(const StringName &p_name, Variant &r_ret) const {
	String s = p_name;
	if (s.begins_with("bus/")) {
		int index = s.get_slice("/", 1).to_int();
		if (index < 0 || index >= buses.size()) {
			return false;
		}

		const Bus &bus = buses[index];

		String what = s.get_slice("/", 2);

		if (what == "name") {
			r_ret = bus.name;
		} else if (what == "solo") {
			r_ret = bus.solo;
		} else if (what == "mute") {
			r_ret = bus.mute;
		} else if (what == "bypass_fx") {
			r_ret = bus.bypass;
		} else if (what == "volume_db") {
			r_ret = bus.volume_db;
		} else if (what == "send") {
			r_ret = bus.send;
		} else if (what == "effect") {
			int which = s.get_slice("/", 3).to_int();
			if (which < 0 || which >= bus.effects.size()) {
				return false;
			}

			const Bus::Effect &fx = bus.effects[which];

			String fxwhat = s.get_slice("/", 4);
			if (fxwhat == "effect") {
				r_ret = fx.effect;
			} else if (fxwhat == "enabled") {
				r_ret = fx.enabled;
			} else {
				return false;
			}

			return true;
		} else {
			return false;
		}

		return true;
	}

	return false;
}

void AudioBusLayout::_get_property_list(List<PropertyInfo> *p_list) const {
	for (int i = 0; i < buses.size(); i++) {
		p_list->push_back(PropertyInfo(Variant::STRING, "bus/" + itos(i) + "/name", PROPERTY_HINT_NONE, "", PROPERTY_USAGE_NO_EDITOR | PROPERTY_USAGE_INTERNAL));
		p_list->push_back(PropertyInfo(Variant::BOOL, "bus/" + itos(i) + "/solo", PROPERTY_HINT_NONE, "", PROPERTY_USAGE_NO_EDITOR | PROPERTY_USAGE_INTERNAL));
		p_list->push_back(PropertyInfo(Variant::BOOL, "bus/" + itos(i) + "/mute", PROPERTY_HINT_NONE, "", PROPERTY_USAGE_NO_EDITOR | PROPERTY_USAGE_INTERNAL));
		p_list->push_back(PropertyInfo(Variant::BOOL, "bus/" + itos(i) + "/bypass_fx", PROPERTY_HINT_NONE, "", PROPERTY_USAGE_NO_EDITOR | PROPERTY_USAGE_INTERNAL));
		p_list->push_back(PropertyInfo(Variant::FLOAT, "bus/" + itos(i) + "/volume_db", PROPERTY_HINT_NONE, "", PROPERTY_USAGE_NO_EDITOR | PROPERTY_USAGE_INTERNAL));
		p_list->push_back(PropertyInfo(Variant::FLOAT, "bus/" + itos(i) + "/send", PROPERTY_HINT_NONE, "", PROPERTY_USAGE_NO_EDITOR | PROPERTY_USAGE_INTERNAL));

		for (int j = 0; j < buses[i].effects.size(); j++) {
			p_list->push_back(PropertyInfo(Variant::OBJECT, "bus/" + itos(i) + "/effect/" + itos(j) + "/effect", PROPERTY_HINT_NONE, "", PROPERTY_USAGE_NO_EDITOR | PROPERTY_USAGE_INTERNAL));
			p_list->push_back(PropertyInfo(Variant::BOOL, "bus/" + itos(i) + "/effect/" + itos(j) + "/enabled", PROPERTY_HINT_NONE, "", PROPERTY_USAGE_NO_EDITOR | PROPERTY_USAGE_INTERNAL));
		}
	}
}

AudioBusLayout::AudioBusLayout() {
	buses.resize(1);
	buses.write[0].name = SceneStringNames::get_singleton()->Master;
}