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 "core/platform/audio/ReverbConvolver.h" 34 35 #include "core/platform/audio/AudioBus.h" 36 #include "core/platform/audio/VectorMath.h" 37 38 namespace WebCore { 39 40 using namespace VectorMath; 41 42 const int InputBufferSize = 8 * 16384; 43 44 // We only process the leading portion of the impulse response in the real-time thread. We don't exceed this length. 45 // It turns out then, that the background thread has about 278msec of scheduling slop. 46 // Empirically, this has been found to be a good compromise between giving enough time for scheduling slop, 47 // while still minimizing the amount of processing done in the primary (high-priority) thread. 48 // This was found to be a good value on Mac OS X, and may work well on other platforms as well, assuming 49 // the very rough scheduling latencies are similar on these time-scales. Of course, this code may need to be 50 // tuned for individual platforms if this assumption is found to be incorrect. 51 const size_t RealtimeFrameLimit = 8192 + 4096; // ~278msec @ 44.1KHz 52 53 const size_t MinFFTSize = 128; 54 const size_t MaxRealtimeFFTSize = 2048; 55 56 static void backgroundThreadEntry(void* threadData) 57 { 58 ReverbConvolver* reverbConvolver = static_cast<ReverbConvolver*>(threadData); 59 reverbConvolver->backgroundThreadEntry(); 60 } 61 62 ReverbConvolver::ReverbConvolver(AudioChannel* impulseResponse, size_t renderSliceSize, size_t maxFFTSize, size_t convolverRenderPhase, bool useBackgroundThreads) 63 : m_impulseResponseLength(impulseResponse->length()) 64 , m_accumulationBuffer(impulseResponse->length() + renderSliceSize) 65 , m_inputBuffer(InputBufferSize) 66 , m_minFFTSize(MinFFTSize) // First stage will have this size - successive stages will double in size each time 67 , m_maxFFTSize(maxFFTSize) // until we hit m_maxFFTSize 68 , m_useBackgroundThreads(useBackgroundThreads) 69 , m_backgroundThread(0) 70 , m_wantsToExit(false) 71 , m_moreInputBuffered(false) 72 { 73 // If we are using background threads then don't exceed this FFT size for the 74 // stages which run in the real-time thread. This avoids having only one or two 75 // large stages (size 16384 or so) at the end which take a lot of time every several 76 // processing slices. This way we amortize the cost over more processing slices. 77 m_maxRealtimeFFTSize = MaxRealtimeFFTSize; 78 79 // For the moment, a good way to know if we have real-time constraint is to check if we're using background threads. 80 // Otherwise, assume we're being run from a command-line tool. 81 bool hasRealtimeConstraint = useBackgroundThreads; 82 83 const float* response = impulseResponse->data(); 84 size_t totalResponseLength = impulseResponse->length(); 85 86 // The total latency is zero because the direct-convolution is used in the leading portion. 87 size_t reverbTotalLatency = 0; 88 89 size_t stageOffset = 0; 90 int i = 0; 91 size_t fftSize = m_minFFTSize; 92 while (stageOffset < totalResponseLength) { 93 size_t stageSize = fftSize / 2; 94 95 // For the last stage, it's possible that stageOffset is such that we're straddling the end 96 // of the impulse response buffer (if we use stageSize), so reduce the last stage's length... 97 if (stageSize + stageOffset > totalResponseLength) 98 stageSize = totalResponseLength - stageOffset; 99 100 // This "staggers" the time when each FFT happens so they don't all happen at the same time 101 int renderPhase = convolverRenderPhase + i * renderSliceSize; 102 103 bool useDirectConvolver = !stageOffset; 104 105 OwnPtr<ReverbConvolverStage> stage = adoptPtr(new ReverbConvolverStage(response, totalResponseLength, reverbTotalLatency, stageOffset, stageSize, fftSize, renderPhase, renderSliceSize, &m_accumulationBuffer, useDirectConvolver)); 106 107 bool isBackgroundStage = false; 108 109 if (this->useBackgroundThreads() && stageOffset > RealtimeFrameLimit) { 110 m_backgroundStages.append(stage.release()); 111 isBackgroundStage = true; 112 } else 113 m_stages.append(stage.release()); 114 115 stageOffset += stageSize; 116 ++i; 117 118 if (!useDirectConvolver) { 119 // Figure out next FFT size 120 fftSize *= 2; 121 } 122 123 if (hasRealtimeConstraint && !isBackgroundStage && fftSize > m_maxRealtimeFFTSize) 124 fftSize = m_maxRealtimeFFTSize; 125 if (fftSize > m_maxFFTSize) 126 fftSize = m_maxFFTSize; 127 } 128 129 // Start up background thread 130 // FIXME: would be better to up the thread priority here. It doesn't need to be real-time, but higher than the default... 131 if (this->useBackgroundThreads() && m_backgroundStages.size() > 0) 132 m_backgroundThread = createThread(WebCore::backgroundThreadEntry, this, "convolution background thread"); 133 } 134 135 ReverbConvolver::~ReverbConvolver() 136 { 137 // Wait for background thread to stop 138 if (useBackgroundThreads() && m_backgroundThread) { 139 m_wantsToExit = true; 140 141 // Wake up thread so it can return 142 { 143 MutexLocker locker(m_backgroundThreadLock); 144 m_moreInputBuffered = true; 145 m_backgroundThreadCondition.signal(); 146 } 147 148 waitForThreadCompletion(m_backgroundThread); 149 } 150 } 151 152 void ReverbConvolver::backgroundThreadEntry() 153 { 154 while (!m_wantsToExit) { 155 // Wait for realtime thread to give us more input 156 m_moreInputBuffered = false; 157 { 158 MutexLocker locker(m_backgroundThreadLock); 159 while (!m_moreInputBuffered && !m_wantsToExit) 160 m_backgroundThreadCondition.wait(m_backgroundThreadLock); 161 } 162 163 // Process all of the stages until their read indices reach the input buffer's write index 164 int writeIndex = m_inputBuffer.writeIndex(); 165 166 // Even though it doesn't seem like every stage needs to maintain its own version of readIndex 167 // we do this in case we want to run in more than one background thread. 168 int readIndex; 169 170 while ((readIndex = m_backgroundStages[0]->inputReadIndex()) != writeIndex) { // FIXME: do better to detect buffer overrun... 171 // The ReverbConvolverStages need to process in amounts which evenly divide half the FFT size 172 const int SliceSize = MinFFTSize / 2; 173 174 // Accumulate contributions from each stage 175 for (size_t i = 0; i < m_backgroundStages.size(); ++i) 176 m_backgroundStages[i]->processInBackground(this, SliceSize); 177 } 178 } 179 } 180 181 void ReverbConvolver::process(const AudioChannel* sourceChannel, AudioChannel* destinationChannel, size_t framesToProcess) 182 { 183 bool isSafe = sourceChannel && destinationChannel && sourceChannel->length() >= framesToProcess && destinationChannel->length() >= framesToProcess; 184 ASSERT(isSafe); 185 if (!isSafe) 186 return; 187 188 const float* source = sourceChannel->data(); 189 float* destination = destinationChannel->mutableData(); 190 bool isDataSafe = source && destination; 191 ASSERT(isDataSafe); 192 if (!isDataSafe) 193 return; 194 195 // Feed input buffer (read by all threads) 196 m_inputBuffer.write(source, framesToProcess); 197 198 // Accumulate contributions from each stage 199 for (size_t i = 0; i < m_stages.size(); ++i) 200 m_stages[i]->process(source, framesToProcess); 201 202 // Finally read from accumulation buffer 203 m_accumulationBuffer.readAndClear(destination, framesToProcess); 204 205 // Now that we've buffered more input, wake up our background thread. 206 207 // Not using a MutexLocker looks strange, but we use a tryLock() instead because this is run on the real-time 208 // thread where it is a disaster for the lock to be contended (causes audio glitching). It's OK if we fail to 209 // signal from time to time, since we'll get to it the next time we're called. We're called repeatedly 210 // and frequently (around every 3ms). The background thread is processing well into the future and has a considerable amount of 211 // leeway here... 212 if (m_backgroundThreadLock.tryLock()) { 213 m_moreInputBuffered = true; 214 m_backgroundThreadCondition.signal(); 215 m_backgroundThreadLock.unlock(); 216 } 217 } 218 219 void ReverbConvolver::reset() 220 { 221 for (size_t i = 0; i < m_stages.size(); ++i) 222 m_stages[i]->reset(); 223 224 for (size_t i = 0; i < m_backgroundStages.size(); ++i) 225 m_backgroundStages[i]->reset(); 226 227 m_accumulationBuffer.reset(); 228 m_inputBuffer.reset(); 229 } 230 231 size_t ReverbConvolver::latencyFrames() const 232 { 233 return 0; 234 } 235 236 } // namespace WebCore 237 238 #endif // ENABLE(WEB_AUDIO) 239