• Home
  • History
  • Annotate
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
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 
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