1/* 2 * Copyright (C) 2016 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 17package org.drrickorang.loopback; 18 19import android.content.Context; 20import android.media.AudioManager; 21import android.os.Handler; 22import android.os.Looper; 23import android.util.Log; 24 25class SoundLevelCalibration { 26 private static final int SECONDS_PER_LEVEL = 1; 27 private static final int MAX_STEPS = 15; // The maximum number of levels that should be tried 28 private static final double CRITICAL_RATIO = 0.41; // Ratio of input over output amplitude at 29 // which the feedback loop neither decays nor 30 // grows (determined experimentally) 31 private static final String TAG = "SoundLevelCalibration"; 32 33 private NativeAudioThread mNativeAudioThread = null; 34 private AudioManager mAudioManager; 35 36 private SoundLevelChangeListener mChangeListener; 37 38 abstract static class SoundLevelChangeListener { 39 // used to run the callback on the UI thread 40 private Handler handler = new Handler(Looper.getMainLooper()); 41 42 abstract void onChange(int newLevel); 43 44 private void go(final int newLevel) { 45 handler.post(new Runnable() { 46 @Override 47 public void run() { 48 onChange(newLevel); 49 } 50 }); 51 } 52 } 53 54 SoundLevelCalibration(int samplingRate, int playerBufferSizeInBytes, 55 int recorderBufferSizeInBytes, int micSource, int performanceMode, Context context) { 56 57 // TODO: Allow capturing wave data without doing glitch detection. 58 CaptureHolder captureHolder = new CaptureHolder(0, "", false, false, false, context, 59 samplingRate); 60 // TODO: Run for less than 1 second. 61 mNativeAudioThread = new NativeAudioThread(samplingRate, playerBufferSizeInBytes, 62 recorderBufferSizeInBytes, micSource, performanceMode, 63 Constant.LOOPBACK_PLUG_AUDIO_THREAD_TEST_TYPE_BUFFER_PERIOD, SECONDS_PER_LEVEL, 64 SECONDS_PER_LEVEL, 0, captureHolder); 65 mAudioManager = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE); 66 } 67 68 // TODO: Allow stopping in the middle of calibration 69 int calibrate() { 70 final int maxLevel = mAudioManager.getStreamMaxVolume(AudioManager.STREAM_MUSIC); 71 int levelBottom = 0; 72 int levelTop = maxLevel + 1; 73 while(levelTop - levelBottom > 1) { 74 int level = (levelBottom + levelTop) / 2; 75 Log.d(TAG, "setting level to " + level); 76 setVolume(level); 77 78 double amplitude = runAudioThread(mNativeAudioThread); 79 mNativeAudioThread = new NativeAudioThread(mNativeAudioThread); // generate fresh thread 80 Log.d(TAG, "calibrate: at sound level " + level + " volume was " + amplitude); 81 82 if (amplitude < Constant.SINE_WAVE_AMPLITUDE * CRITICAL_RATIO) { 83 levelBottom = level; 84 } else { 85 levelTop = level; 86 } 87 } 88 // At this point, levelBottom has the highest proper value, if there is one (0 otherwise) 89 Log.d(TAG, "Final level: " + levelBottom); 90 setVolume(levelBottom); 91 return levelBottom; 92 } 93 94 private double runAudioThread(NativeAudioThread thread) { 95 // runs the native audio thread and returns the average amplitude 96 thread.start(); 97 try { 98 thread.join(); 99 } catch (InterruptedException e) { 100 e.printStackTrace(); 101 } 102 double[] data = thread.getWaveData(); 103 return averageAmplitude(data); 104 } 105 106 // TODO: Only gives accurate results for an undistorted sine wave. Check for distortion. 107 private static double averageAmplitude(double[] data) { 108 if (data == null || data.length == 0) { 109 return 0; // no data is present 110 } 111 double sumSquare = 0; 112 for (double x : data) { 113 sumSquare += x * x; 114 } 115 return Math.sqrt(2.0 * sumSquare / data.length); // amplitude of the sine wave 116 } 117 118 private void setVolume(int level) { 119 mAudioManager.setStreamVolume(AudioManager.STREAM_MUSIC, level, 0); 120 if (mChangeListener != null) { 121 mChangeListener.go(level); 122 } 123 } 124 125 void setChangeListener(SoundLevelChangeListener changeListener) { 126 mChangeListener = changeListener; 127 } 128} 129