godot/servers/audio/effects/audio_effect_stereo_enhance.cpp

/*************************************************************************/
/*  audio_effect_stereo_enhance.cpp                                      */
/*************************************************************************/
/*                       This file is part of:                           */
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/* Copyright (c) 2007-2021 Juan Linietsky, Ariel Manzur.                 */
/* Copyright (c) 2014-2021 Godot Engine contributors (cf. AUTHORS.md).   */
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#include "audio_effect_stereo_enhance.h"
#include "servers/audio_server.h"
void AudioEffectStereoEnhanceInstance::process(const AudioFrame *p_src_frames, AudioFrame *p_dst_frames, int p_frame_count) {
	float intensity = base->pan_pullout;
	bool surround_mode = base->surround > 0;
	float surround_amount = base->surround;
	unsigned int delay_frames = (base->time_pullout / 1000.0) * AudioServer::get_singleton()->get_mix_rate();

	for (int i = 0; i < p_frame_count; i++) {
		float l = p_src_frames[i].l;
		float r = p_src_frames[i].r;

		float center = (l + r) / 2.0f;

		l = (center + (l - center) * intensity);
		r = (center + (r - center) * intensity);

		if (surround_mode) {
			float val = (l + r) / 2.0;

			delay_ringbuff[ringbuff_pos & ringbuff_mask] = val;

			float out = delay_ringbuff[(ringbuff_pos - delay_frames) & ringbuff_mask] * surround_amount;

			l += out;
			r += -out;
		} else {
			float val = r;

			delay_ringbuff[ringbuff_pos & ringbuff_mask] = val;

			//r is delayed
			r = delay_ringbuff[(ringbuff_pos - delay_frames) & ringbuff_mask];
			;
		}

		p_dst_frames[i].l = l;
		p_dst_frames[i].r = r;
		ringbuff_pos++;
	}
}

AudioEffectStereoEnhanceInstance::~AudioEffectStereoEnhanceInstance() {
	memdelete_arr(delay_ringbuff);
}

Ref<AudioEffectInstance> AudioEffectStereoEnhance::instantiate() {
	Ref<AudioEffectStereoEnhanceInstance> ins;
	ins.instantiate();

	ins->base = Ref<AudioEffectStereoEnhance>(this);

	float ring_buffer_max_size = AudioEffectStereoEnhanceInstance::MAX_DELAY_MS + 2;
	ring_buffer_max_size /= 1000.0; //convert to seconds
	ring_buffer_max_size *= AudioServer::get_singleton()->get_mix_rate();

	int ringbuff_size = (int)ring_buffer_max_size;

	int bits = 0;

	while (ringbuff_size > 0) {
		bits++;
		ringbuff_size /= 2;
	}

	ringbuff_size = 1 << bits;
	ins->ringbuff_mask = ringbuff_size - 1;
	ins->ringbuff_pos = 0;

	ins->delay_ringbuff = memnew_arr(float, ringbuff_size);

	return ins;
}

void AudioEffectStereoEnhance::set_pan_pullout(float p_amount) {
	pan_pullout = p_amount;
}

float AudioEffectStereoEnhance::get_pan_pullout() const {
	return pan_pullout;
}

void AudioEffectStereoEnhance::set_time_pullout(float p_amount) {
	time_pullout = p_amount;
}

float AudioEffectStereoEnhance::get_time_pullout() const {
	return time_pullout;
}

void AudioEffectStereoEnhance::set_surround(float p_amount) {
	surround = p_amount;
}

float AudioEffectStereoEnhance::get_surround() const {
	return surround;
}

void AudioEffectStereoEnhance::_bind_methods() {
	ClassDB::bind_method(D_METHOD("set_pan_pullout", "amount"), &AudioEffectStereoEnhance::set_pan_pullout);
	ClassDB::bind_method(D_METHOD("get_pan_pullout"), &AudioEffectStereoEnhance::get_pan_pullout);

	ClassDB::bind_method(D_METHOD("set_time_pullout", "amount"), &AudioEffectStereoEnhance::set_time_pullout);
	ClassDB::bind_method(D_METHOD("get_time_pullout"), &AudioEffectStereoEnhance::get_time_pullout);

	ClassDB::bind_method(D_METHOD("set_surround", "amount"), &AudioEffectStereoEnhance::set_surround);
	ClassDB::bind_method(D_METHOD("get_surround"), &AudioEffectStereoEnhance::get_surround);

	ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "pan_pullout", PROPERTY_HINT_RANGE, "0,4,0.01"), "set_pan_pullout", "get_pan_pullout");
	ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "time_pullout_ms", PROPERTY_HINT_RANGE, "0,50,0.01"), "set_time_pullout", "get_time_pullout");
	ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "surround", PROPERTY_HINT_RANGE, "0,1,0.01"), "set_surround", "get_surround");
}

AudioEffectStereoEnhance::AudioEffectStereoEnhance() {
	pan_pullout = 1;
	time_pullout = 0;
	surround = 0;
}