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
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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
ReverbConvolver(AudioChannel * impulseResponse,size_t renderSliceSize,size_t maxFFTSize,size_t convolverRenderPhase,bool useBackgroundThreads)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
~ReverbConvolver()128 ReverbConvolver::~ReverbConvolver()
129 {
130 // Wait for background thread to stop
131 m_backgroundThread.clear();
132 }
133
processInBackground()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
process(const AudioChannel * sourceChannel,AudioChannel * destinationChannel,size_t framesToProcess)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
reset()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
latencyFrames() const194 size_t ReverbConvolver::latencyFrames() const
195 {
196 return 0;
197 }
198
199 } // namespace blink
200
201 #endif // ENABLE(WEB_AUDIO)
202