1 /* 2 * Copyright (C) 2010 Google Inc. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of 14 * its contributors may be used to endorse or promote products derived 15 * from this software without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY 18 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 19 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 20 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY 21 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 22 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 23 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 24 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29 #include "config.h" 30 31 #if ENABLE(WEB_AUDIO) 32 33 #include "platform/audio/ReverbConvolver.h" 34 35 #include "platform/Task.h" 36 #include "platform/audio/AudioBus.h" 37 #include "platform/audio/VectorMath.h" 38 #include "public/platform/Platform.h" 39 #include "public/platform/WebThread.h" 40 41 namespace blink { 42 43 using namespace VectorMath; 44 45 const int InputBufferSize = 8 * 16384; 46 47 // We only process the leading portion of the impulse response in the real-time thread. We don't exceed this length. 48 // It turns out then, that the background thread has about 278msec of scheduling slop. 49 // Empirically, this has been found to be a good compromise between giving enough time for scheduling slop, 50 // while still minimizing the amount of processing done in the primary (high-priority) thread. 51 // This was found to be a good value on Mac OS X, and may work well on other platforms as well, assuming 52 // the very rough scheduling latencies are similar on these time-scales. Of course, this code may need to be 53 // tuned for individual platforms if this assumption is found to be incorrect. 54 const size_t RealtimeFrameLimit = 8192 + 4096; // ~278msec @ 44.1KHz 55 56 const size_t MinFFTSize = 128; 57 const size_t MaxRealtimeFFTSize = 2048; 58 59 ReverbConvolver::ReverbConvolver(AudioChannel* impulseResponse, size_t renderSliceSize, size_t maxFFTSize, size_t convolverRenderPhase, bool useBackgroundThreads) 60 : m_impulseResponseLength(impulseResponse->length()) 61 , m_accumulationBuffer(impulseResponse->length() + renderSliceSize) 62 , m_inputBuffer(InputBufferSize) 63 , m_minFFTSize(MinFFTSize) // First stage will have this size - successive stages will double in size each time 64 , m_maxFFTSize(maxFFTSize) // until we hit m_maxFFTSize 65 { 66 // If we are using background threads then don't exceed this FFT size for the 67 // stages which run in the real-time thread. This avoids having only one or two 68 // large stages (size 16384 or so) at the end which take a lot of time every several 69 // processing slices. This way we amortize the cost over more processing slices. 70 m_maxRealtimeFFTSize = MaxRealtimeFFTSize; 71 72 // For the moment, a good way to know if we have real-time constraint is to check if we're using background threads. 73 // Otherwise, assume we're being run from a command-line tool. 74 bool hasRealtimeConstraint = useBackgroundThreads; 75 76 const float* response = impulseResponse->data(); 77 size_t totalResponseLength = impulseResponse->length(); 78 79 // The total latency is zero because the direct-convolution is used in the leading portion. 80 size_t reverbTotalLatency = 0; 81 82 size_t stageOffset = 0; 83 int i = 0; 84 size_t fftSize = m_minFFTSize; 85 while (stageOffset < totalResponseLength) { 86 size_t stageSize = fftSize / 2; 87 88 // For the last stage, it's possible that stageOffset is such that we're straddling the end 89 // of the impulse response buffer (if we use stageSize), so reduce the last stage's length... 90 if (stageSize + stageOffset > totalResponseLength) 91 stageSize = totalResponseLength - stageOffset; 92 93 // This "staggers" the time when each FFT happens so they don't all happen at the same time 94 int renderPhase = convolverRenderPhase + i * renderSliceSize; 95 96 bool useDirectConvolver = !stageOffset; 97 98 OwnPtr<ReverbConvolverStage> stage = adoptPtr(new ReverbConvolverStage(response, totalResponseLength, reverbTotalLatency, stageOffset, stageSize, fftSize, renderPhase, renderSliceSize, &m_accumulationBuffer, useDirectConvolver)); 99 100 bool isBackgroundStage = false; 101 102 if (useBackgroundThreads && stageOffset > RealtimeFrameLimit) { 103 m_backgroundStages.append(stage.release()); 104 isBackgroundStage = true; 105 } else 106 m_stages.append(stage.release()); 107 108 stageOffset += stageSize; 109 ++i; 110 111 if (!useDirectConvolver) { 112 // Figure out next FFT size 113 fftSize *= 2; 114 } 115 116 if (hasRealtimeConstraint && !isBackgroundStage && fftSize > m_maxRealtimeFFTSize) 117 fftSize = m_maxRealtimeFFTSize; 118 if (fftSize > m_maxFFTSize) 119 fftSize = m_maxFFTSize; 120 } 121 122 // Start up background thread 123 // FIXME: would be better to up the thread priority here. It doesn't need to be real-time, but higher than the default... 124 if (useBackgroundThreads && m_backgroundStages.size() > 0) 125 m_backgroundThread = adoptPtr(Platform::current()->createThread("Reverb convolution background thread")); 126 } 127 128 ReverbConvolver::~ReverbConvolver() 129 { 130 // Wait for background thread to stop 131 m_backgroundThread.clear(); 132 } 133 134 void ReverbConvolver::processInBackground() 135 { 136 // Process all of the stages until their read indices reach the input buffer's write index 137 int writeIndex = m_inputBuffer.writeIndex(); 138 139 // Even though it doesn't seem like every stage needs to maintain its own version of readIndex 140 // we do this in case we want to run in more than one background thread. 141 int readIndex; 142 143 while ((readIndex = m_backgroundStages[0]->inputReadIndex()) != writeIndex) { // FIXME: do better to detect buffer overrun... 144 // The ReverbConvolverStages need to process in amounts which evenly divide half the FFT size 145 const int SliceSize = MinFFTSize / 2; 146 147 // Accumulate contributions from each stage 148 for (size_t i = 0; i < m_backgroundStages.size(); ++i) 149 m_backgroundStages[i]->processInBackground(this, SliceSize); 150 } 151 } 152 153 void ReverbConvolver::process(const AudioChannel* sourceChannel, AudioChannel* destinationChannel, size_t framesToProcess) 154 { 155 bool isSafe = sourceChannel && destinationChannel && sourceChannel->length() >= framesToProcess && destinationChannel->length() >= framesToProcess; 156 ASSERT(isSafe); 157 if (!isSafe) 158 return; 159 160 const float* source = sourceChannel->data(); 161 float* destination = destinationChannel->mutableData(); 162 bool isDataSafe = source && destination; 163 ASSERT(isDataSafe); 164 if (!isDataSafe) 165 return; 166 167 // Feed input buffer (read by all threads) 168 m_inputBuffer.write(source, framesToProcess); 169 170 // Accumulate contributions from each stage 171 for (size_t i = 0; i < m_stages.size(); ++i) 172 m_stages[i]->process(source, framesToProcess); 173 174 // Finally read from accumulation buffer 175 m_accumulationBuffer.readAndClear(destination, framesToProcess); 176 177 // Now that we've buffered more input, post another task to the background thread. 178 if (m_backgroundThread) 179 m_backgroundThread->postTask(new Task(WTF::bind(&ReverbConvolver::processInBackground, this))); 180 } 181 182 void ReverbConvolver::reset() 183 { 184 for (size_t i = 0; i < m_stages.size(); ++i) 185 m_stages[i]->reset(); 186 187 for (size_t i = 0; i < m_backgroundStages.size(); ++i) 188 m_backgroundStages[i]->reset(); 189 190 m_accumulationBuffer.reset(); 191 m_inputBuffer.reset(); 192 } 193 194 size_t ReverbConvolver::latencyFrames() const 195 { 196 return 0; 197 } 198 199 } // namespace blink 200 201 #endif // ENABLE(WEB_AUDIO) 202