Add AudioEffectHardLimiter as a rework of audio limiter effect

2 files changed, 250 insertions, 0 deletions

diff --git a/servers/audio/effects/audio_effect_hard_limiter.cpp b/servers/audio/effects/audio_effect_hard_limiter.cpp
new file mode 100644
index 0000000000..e717557af2
--- /dev/null
+++ b/servers/audio/effects/audio_effect_hard_limiter.cpp
@@ -0,0 +1,161 @@
+/**************************************************************************/
+/*  audio_effect_hard_limiter.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_effect_hard_limiter.h"
+
+#include "servers/audio_server.h"
+
+void AudioEffectHardLimiterInstance::process(const AudioFrame *p_src_frames, AudioFrame *p_dst_frames, int p_frame_count) {
+	float sample_rate = AudioServer::get_singleton()->get_mix_rate();
+
+	float ceiling = Math::db_to_linear(base->ceiling);
+	float release = base->release;
+	float attack = base->attack;
+	float pre_gain = Math::db_to_linear(base->pre_gain);
+
+	for (int i = 0; i < p_frame_count; i++) {
+		float sample_left = p_src_frames[i].left;
+		float sample_right = p_src_frames[i].right;
+
+		sample_left *= pre_gain;
+		sample_right *= pre_gain;
+
+		float largest_sample = MAX(ABS(sample_left), ABS(sample_right));
+
+		release_factor = MAX(0.0, release_factor - 1.0 / sample_rate);
+		release_factor = MIN(release_factor, release);
+
+		if (release_factor > 0.0) {
+			gain = Math::lerp(gain_target, 1.0f, 1.0f - release_factor / release);
+		}
+
+		if (largest_sample * gain > ceiling) {
+			gain_target = ceiling / largest_sample;
+			release_factor = release;
+			attack_factor = attack;
+		}
+
+		// Lerp gain over attack time to avoid distortion.
+		attack_factor = MAX(0.0f, attack_factor - 1.0f / sample_rate);
+		if (attack_factor > 0.0) {
+			gain = Math::lerp(gain_target, gain, 1.0f - attack_factor / attack);
+		}
+
+		int bucket_id = gain_bucket_cursor / gain_bucket_size;
+
+		// If first item within the current bucket, reset the bucket.
+		if (gain_bucket_cursor % gain_bucket_size == 0) {
+			gain_buckets[bucket_id] = 1.0f;
+		}
+
+		gain_buckets[bucket_id] = MIN(gain_buckets[bucket_id], gain);
+
+		gain_bucket_cursor = (gain_bucket_cursor + 1) % gain_samples_to_store;
+
+		for (int j = 0; j < (int)gain_buckets.size(); j++) {
+			gain = MIN(gain, gain_buckets[j]);
+		}
+
+		// Introduce latency by grabbing the AudioFrame stored previously,
+		// then overwrite it with current audioframe, then update circular
+		// buffer cursor.
+		float dst_buffer_left = sample_buffer_left[sample_cursor];
+		float dst_buffer_right = sample_buffer_right[sample_cursor];
+
+		sample_buffer_left[sample_cursor] = sample_left;
+		sample_buffer_right[sample_cursor] = sample_right;
+
+		sample_cursor = (sample_cursor + 1) % sample_buffer_left.size();
+
+		p_dst_frames[i].left = dst_buffer_left * gain;
+		p_dst_frames[i].right = dst_buffer_right * gain;
+	}
+}
+
+Ref<AudioEffectInstance> AudioEffectHardLimiter::instantiate() {
+	Ref<AudioEffectHardLimiterInstance> ins;
+	ins.instantiate();
+	ins->base = Ref<AudioEffectHardLimiter>(this);
+
+	float mix_rate = AudioServer::get_singleton()->get_mix_rate();
+
+	for (int i = 0; i < (int)Math::ceil(mix_rate * attack) + 1; i++) {
+		ins->sample_buffer_left.push_back(0.0f);
+		ins->sample_buffer_right.push_back(0.0f);
+	}
+
+	ins->gain_samples_to_store = (int)Math::ceil(mix_rate * (attack + sustain) + 1);
+	ins->gain_bucket_size = (int)(mix_rate * attack);
+
+	for (int i = 0; i < ins->gain_samples_to_store; i += ins->gain_bucket_size) {
+		ins->gain_buckets.push_back(1.0f);
+	}
+
+	return ins;
+}
+
+void AudioEffectHardLimiter::set_ceiling_db(float p_ceiling) {
+	ceiling = p_ceiling;
+}
+
+float AudioEffectHardLimiter::get_ceiling_db() const {
+	return ceiling;
+}
+
+float AudioEffectHardLimiter::get_pre_gain_db() const {
+	return pre_gain;
+}
+
+void AudioEffectHardLimiter::set_pre_gain_db(const float p_pre_gain) {
+	pre_gain = p_pre_gain;
+}
+
+float AudioEffectHardLimiter::get_release() const {
+	return release;
+}
+
+void AudioEffectHardLimiter::set_release(const float p_release) {
+	release = p_release;
+}
+
+void AudioEffectHardLimiter::_bind_methods() {
+	ClassDB::bind_method(D_METHOD("set_ceiling_db", "ceiling"), &AudioEffectHardLimiter::set_ceiling_db);
+	ClassDB::bind_method(D_METHOD("get_ceiling_db"), &AudioEffectHardLimiter::get_ceiling_db);
+
+	ClassDB::bind_method(D_METHOD("set_pre_gain_db", "p_pre_gain"), &AudioEffectHardLimiter::set_pre_gain_db);
+	ClassDB::bind_method(D_METHOD("get_pre_gain_db"), &AudioEffectHardLimiter::get_pre_gain_db);
+
+	ClassDB::bind_method(D_METHOD("set_release", "p_release"), &AudioEffectHardLimiter::set_release);
+	ClassDB::bind_method(D_METHOD("get_release"), &AudioEffectHardLimiter::get_release);
+
+	ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "pre_gain_db", PROPERTY_HINT_RANGE, "-24,24,0.01,suffix:dB"), "set_pre_gain_db", "get_pre_gain_db");
+	ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "ceiling_db", PROPERTY_HINT_RANGE, "-24,0.0,0.01,suffix:dB"), "set_ceiling_db", "get_ceiling_db");
+	ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "release", PROPERTY_HINT_RANGE, "0.01,3,0.01"), "set_release", "get_release");
+}
diff --git a/servers/audio/effects/audio_effect_hard_limiter.h b/servers/audio/effects/audio_effect_hard_limiter.h
new file mode 100644
index 0000000000..7e28480797
--- /dev/null
+++ b/servers/audio/effects/audio_effect_hard_limiter.h
@@ -0,0 +1,89 @@
+/**************************************************************************/
+/*  audio_effect_hard_limiter.h                                           */
+/**************************************************************************/
+/*                         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.                 */
+/**************************************************************************/
+
+#ifndef AUDIO_EFFECT_HARD_LIMITER_H
+#define AUDIO_EFFECT_HARD_LIMITER_H
+
+#include "servers/audio/audio_effect.h"
+
+class AudioEffectHardLimiter;
+
+class AudioEffectHardLimiterInstance : public AudioEffectInstance {
+	GDCLASS(AudioEffectHardLimiterInstance, AudioEffectInstance);
+	friend class AudioEffectHardLimiter;
+	Ref<AudioEffectHardLimiter> base;
+
+private:
+	int sample_cursor = 0;
+
+	float release_factor = 0;
+	float attack_factor = 0;
+	float gain = 1;
+	float gain_target = 1;
+
+	LocalVector<float> sample_buffer_left;
+	LocalVector<float> sample_buffer_right;
+
+	int gain_samples_to_store = 0;
+	int gain_bucket_cursor = 0;
+	int gain_bucket_size = 0;
+	LocalVector<float> gain_buckets;
+
+public:
+	virtual void process(const AudioFrame *p_src_frames, AudioFrame *p_dst_frames, int p_frame_count) override;
+};
+
+class AudioEffectHardLimiter : public AudioEffect {
+	GDCLASS(AudioEffectHardLimiter, AudioEffect);
+
+	friend class AudioEffectHardLimiterInstance;
+	float pre_gain = 0.0f;
+	float ceiling = -0.3f;
+	float sustain = 0.02f;
+	float release = 0.1f;
+	const float attack = 0.002;
+
+protected:
+	static void _bind_methods();
+
+public:
+	void set_ceiling_db(float p_ceiling);
+	float get_ceiling_db() const;
+
+	void set_release(float p_release);
+	float get_release() const;
+
+	void set_pre_gain_db(float p_pre_gain);
+	float get_pre_gain_db() const;
+
+	Ref<AudioEffectInstance> instantiate() override;
+};
+
+#endif // AUDIO_EFFECT_HARD_LIMITER_H