text: /*************************************************************************/
  /*  audio_effect_amplify.cpp                                             */
  /*************************************************************************/
  /*                       This file is part of:                           */
  /*                           GODOT ENGINE                                */
  /*                      https://godotengine.org                          */
  /*************************************************************************/
  /* Copyright (c) 2007-2021 Juan Linietsky, Ariel Manzur.                 */
  /* Copyright (c) 2014-2021 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       */
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  /* 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.*/
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  /*************************************************************************/
  
  #include "audio_effect_amplify.h"
  
  void AudioEffectAmplifyInstance::process(const AudioFrame *p_src_frames, AudioFrame *p_dst_frames, int p_frame_count) {
  	//multiply volume interpolating to avoid clicks if this changes
  	float volume_db = base->volume_db;
  	float vol = Math::db2linear(mix_volume_db);
  	float vol_inc = (Math::db2linear(volume_db) - vol) / float(p_frame_count);
  
  	for (int i = 0; i < p_frame_count; i++) {
  		p_dst_frames[i] = p_src_frames[i] * vol;
  		vol += vol_inc;
  	}
  	//set volume for next mix
  	mix_volume_db = volume_db;
  }
  
  Ref<AudioEffectInstance> AudioEffectAmplify::instance() {
  	Ref<AudioEffectAmplifyInstance> ins;
  	ins.instance();
  	ins->base = Ref<AudioEffectAmplify>(this);
  	ins->mix_volume_db = volume_db;
  	return ins;
  }
  
  void AudioEffectAmplify::set_volume_db(float p_volume) {
  	volume_db = p_volume;
  }
  
  float AudioEffectAmplify::get_volume_db() const {
  	return volume_db;
  }
  
  void AudioEffectAmplify::_bind_methods() {
  	ClassDB::bind_method(D_METHOD("set_volume_db", "volume"), &AudioEffectAmplify::set_volume_db);
  	ClassDB::bind_method(D_METHOD("get_volume_db"), &AudioEffectAmplify::get_volume_db);
  
  	ADD_PROPERTY(PropertyInfo(Variant::REAL, "volume_db", PROPERTY_HINT_RANGE, "-80,24,0.01"), "set_volume_db", "get_volume_db");
  }
  
  AudioEffectAmplify::AudioEffectAmplify() {
  	volume_db = 0;
  }
  