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100 lines
3.0 KiB
100 lines
3.0 KiB
/*
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* Copyright 2010 Google Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.levien.synthesizer.core.model.modules;
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import com.levien.synthesizer.core.model.CachedSignalProvider;
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import com.levien.synthesizer.core.model.SignalProvider;
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import com.levien.synthesizer.core.model.SynthesisTime;
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/**
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* The Echo module produces an echo effect by mixing its current input with its earlier input.
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*/
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public class Echo extends CachedSignalProvider {
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/**
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* Creates a new Echo module.
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* @param source - The input to the echo module.
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* @param mix - How wet/dry the output is, i.e. the depth of the effect.
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* @param delay - The length of time in seconds between input and its first repetition.
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* @param sampleRateInHz - Sample rate, used to compute buffer size from delay time.
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*/
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public Echo(SignalProvider source,
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SignalProvider mix,
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SignalProvider delay,
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double sampleRateInHz) {
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source_ = source;
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mix_ = mix;
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delay_ = delay;
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sampleRateInHz_ = sampleRateInHz;
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buffer_ = new double[MAX_BUFFER_SIZE];
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for (int i = 0; i < MAX_BUFFER_SIZE; ++i) {
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buffer_[i] = 0.0;
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}
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bufferSize_ = 0;
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current_ = 0;
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previousDelay_ = 0.0;
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}
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protected void maybeUpdateDelay(double delay) {
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// As an optimization, just bail if the delay value hasn't changed.
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if (previousDelay_ == delay) {
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return;
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}
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previousDelay_ = delay;
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int newBufferSize = 0;
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if (delay != 0.0) {
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newBufferSize = (int)Math.round(delay * sampleRateInHz_);
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}
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if (bufferSize_ == newBufferSize) {
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return;
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}
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bufferSize_ = newBufferSize;
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if (bufferSize_ < 1) {
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bufferSize_ = 0;
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}
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if (bufferSize_ > MAX_BUFFER_SIZE) {
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bufferSize_ = MAX_BUFFER_SIZE;
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}
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}
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@Override
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protected double computeValue(SynthesisTime time) {
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maybeUpdateDelay(delay_.getValue(time));
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double input = source_.getValue(time);
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double mix = mix_.getValue(time);
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if (bufferSize_ == 0) {
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return (1.0 - mix) * input;
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} else {
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double value = mix * buffer_[current_] + (1.0 - mix) * input;
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buffer_[current_] = value;
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current_ = (current_ + 1) % bufferSize_;
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return value;
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}
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}
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private SignalProvider source_;
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private SignalProvider mix_;
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private SignalProvider delay_;
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private double previousDelay_;
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private double[] buffer_;
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private int bufferSize_;
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private double sampleRateInHz_;
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private int current_;
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private final static int MAX_BUFFER_SIZE = 55125;
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}
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