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MidiScope / src / com.example.android.common.midi / synth /

SynthVoice.java

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/*
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 * Copyright (C) 2015 The Android Open Source Project
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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.example.android.common.midi.synth;
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/**
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 * Base class for a polyphonic synthesizer voice.
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 */
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public abstract class SynthVoice {
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    private int mNoteIndex;
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    private float mAmplitude;
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    public static final int STATE_OFF = 0;
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    public static final int STATE_ON = 1;
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    private int mState = STATE_OFF;
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    public SynthVoice() {
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        mNoteIndex = -1;
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    }
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    public void noteOn(int noteIndex, int velocity) {
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        mState = STATE_ON;
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        this.mNoteIndex = noteIndex;
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        setAmplitude(velocity / 128.0f);
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    }
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    public void noteOff() {
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        mState = STATE_OFF;
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    }
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    /**
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     * Add the output of this voice to an output buffer.
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     *
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     * @param outputBuffer
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     * @param samplesPerFrame
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     * @param level
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     */
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    public void mix(float[] outputBuffer, int samplesPerFrame, float level) {
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        int numFrames = outputBuffer.length / samplesPerFrame;
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        for (int i = 0; i < numFrames; i++) {
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            float output = render();
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            int offset = i * samplesPerFrame;
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            for (int jf = 0; jf < samplesPerFrame; jf++) {
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                outputBuffer[offset + jf] += output * level;
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            }
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        }
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    }
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    public abstract float render();
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    public boolean isDone() {
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        return mState == STATE_OFF;
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    }
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    public int getNoteIndex() {
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        return mNoteIndex;
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    }
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    public float getAmplitude() {
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        return mAmplitude;
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    }
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    public void setAmplitude(float amplitude) {
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        this.mAmplitude = amplitude;
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    }
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    /**
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     * @param scaler
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     */
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    public void setFrequencyScaler(float scaler) {
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    }
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}
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