1 /* 2 * Copyright (C) 2015 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.example.android.common.midi.synth; 18 19 /** 20 * Base class for a polyphonic synthesizer voice. 21 */ 22 public abstract class SynthVoice { 23 private int mNoteIndex; 24 private float mAmplitude; 25 public static final int STATE_OFF = 0; 26 public static final int STATE_ON = 1; 27 private int mState = STATE_OFF; 28 SynthVoice()29 public SynthVoice() { 30 mNoteIndex = -1; 31 } 32 noteOn(int noteIndex, int velocity)33 public void noteOn(int noteIndex, int velocity) { 34 mState = STATE_ON; 35 this.mNoteIndex = noteIndex; 36 setAmplitude(velocity / 128.0f); 37 } 38 noteOff()39 public void noteOff() { 40 mState = STATE_OFF; 41 } 42 43 /** 44 * Add the output of this voice to an output buffer. 45 * 46 * @param outputBuffer 47 * @param samplesPerFrame 48 * @param level 49 */ mix(float[] outputBuffer, int samplesPerFrame, float level)50 public void mix(float[] outputBuffer, int samplesPerFrame, float level) { 51 int numFrames = outputBuffer.length / samplesPerFrame; 52 for (int i = 0; i < numFrames; i++) { 53 float output = render(); 54 int offset = i * samplesPerFrame; 55 for (int jf = 0; jf < samplesPerFrame; jf++) { 56 outputBuffer[offset + jf] += output * level; 57 } 58 } 59 } 60 render()61 public abstract float render(); 62 isDone()63 public boolean isDone() { 64 return mState == STATE_OFF; 65 } 66 getNoteIndex()67 public int getNoteIndex() { 68 return mNoteIndex; 69 } 70 getAmplitude()71 public float getAmplitude() { 72 return mAmplitude; 73 } 74 setAmplitude(float amplitude)75 public void setAmplitude(float amplitude) { 76 this.mAmplitude = amplitude; 77 } 78 79 /** 80 * @param scaler 81 */ setFrequencyScaler(float scaler)82 public void setFrequencyScaler(float scaler) { 83 } 84 85 } 86