1 /*
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15  *     from this software without specific prior written permission.
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27  */
28 
29 #include "config.h"
30 
31 #if ENABLE(WEB_AUDIO)
32 
33 #include "ReverbConvolverStage.h"
34 
35 #include "VectorMath.h"
36 #include "ReverbAccumulationBuffer.h"
37 #include "ReverbConvolver.h"
38 #include "ReverbInputBuffer.h"
39 #include <wtf/OwnPtr.h>
40 #include <wtf/PassOwnPtr.h>
41 
42 namespace WebCore {
43 
44 using namespace VectorMath;
45 
ReverbConvolverStage(float * impulseResponse,size_t responseLength,size_t reverbTotalLatency,size_t stageOffset,size_t stageLength,size_t fftSize,size_t renderPhase,size_t renderSliceSize,ReverbAccumulationBuffer * accumulationBuffer)46 ReverbConvolverStage::ReverbConvolverStage(float* impulseResponse, size_t responseLength, size_t reverbTotalLatency, size_t stageOffset, size_t stageLength,
47                                            size_t fftSize, size_t renderPhase, size_t renderSliceSize, ReverbAccumulationBuffer* accumulationBuffer)
48     : m_fftKernel(fftSize)
49     , m_accumulationBuffer(accumulationBuffer)
50     , m_accumulationReadIndex(0)
51     , m_inputReadIndex(0)
52     , m_impulseResponseLength(responseLength)
53 {
54     ASSERT(impulseResponse);
55     ASSERT(accumulationBuffer);
56 
57     m_fftKernel.doPaddedFFT(impulseResponse + stageOffset, stageLength);
58     m_convolver = adoptPtr(new FFTConvolver(fftSize));
59     m_temporaryBuffer.resize(renderSliceSize);
60 
61     // The convolution stage at offset stageOffset needs to have a corresponding delay to cancel out the offset.
62     size_t totalDelay = stageOffset + reverbTotalLatency;
63 
64     // But, the FFT convolution itself incurs fftSize / 2 latency, so subtract this out...
65     size_t halfSize = fftSize / 2;
66     ASSERT(totalDelay >= halfSize);
67     if (totalDelay >= halfSize)
68         totalDelay -= halfSize;
69 
70     // We divide up the total delay, into pre and post delay sections so that we can schedule at exactly the moment when the FFT will happen.
71     // This is coordinated with the other stages, so they don't all do their FFTs at the same time...
72     int maxPreDelayLength = std::min(halfSize, totalDelay);
73     m_preDelayLength = totalDelay > 0 ? renderPhase % maxPreDelayLength : 0;
74     if (m_preDelayLength > totalDelay)
75         m_preDelayLength = 0;
76 
77     m_postDelayLength = totalDelay - m_preDelayLength;
78     m_preReadWriteIndex = 0;
79     m_framesProcessed = 0; // total frames processed so far
80 
81     m_preDelayBuffer.resize(m_preDelayLength < fftSize ? fftSize : m_preDelayLength);
82 }
83 
processInBackground(ReverbConvolver * convolver,size_t framesToProcess)84 void ReverbConvolverStage::processInBackground(ReverbConvolver* convolver, size_t framesToProcess)
85 {
86     ReverbInputBuffer* inputBuffer = convolver->inputBuffer();
87     float* source = inputBuffer->directReadFrom(&m_inputReadIndex, framesToProcess);
88     process(source, framesToProcess);
89 }
90 
process(float * source,size_t framesToProcess)91 void ReverbConvolverStage::process(float* source, size_t framesToProcess)
92 {
93     ASSERT(source);
94     if (!source)
95         return;
96 
97     // Deal with pre-delay stream : note special handling of zero delay.
98 
99     float* preDelayedSource;
100     float* temporaryBuffer;
101     bool isTemporaryBufferSafe = false;
102     if (m_preDelayLength > 0) {
103         // Handles both the read case (call to process() ) and the write case (memcpy() )
104         bool isPreDelaySafe = m_preReadWriteIndex + framesToProcess <= m_preDelayBuffer.size();
105         ASSERT(isPreDelaySafe);
106         if (!isPreDelaySafe)
107             return;
108 
109         isTemporaryBufferSafe = framesToProcess <= m_temporaryBuffer.size();
110 
111         preDelayedSource = m_preDelayBuffer.data() + m_preReadWriteIndex;
112         temporaryBuffer = m_temporaryBuffer.data();
113     } else {
114         // Zero delay
115         preDelayedSource = source;
116         temporaryBuffer = m_preDelayBuffer.data();
117 
118         isTemporaryBufferSafe = framesToProcess <= m_preDelayBuffer.size();
119     }
120 
121     ASSERT(isTemporaryBufferSafe);
122     if (!isTemporaryBufferSafe)
123         return;
124 
125     int writeIndex = 0;
126 
127     if (m_framesProcessed < m_preDelayLength) {
128         // For the first m_preDelayLength frames don't process the convolver, instead simply buffer in the pre-delay.
129         // But while buffering the pre-delay, we still need to update our index.
130         m_accumulationBuffer->updateReadIndex(&m_accumulationReadIndex, framesToProcess);
131     } else {
132         // Now, run the convolution (into the delay buffer).
133         // An expensive FFT will happen every fftSize / 2 frames.
134         // We process in-place here...
135         m_convolver->process(&m_fftKernel, preDelayedSource, temporaryBuffer, framesToProcess);
136 
137         // Now accumulate into reverb's accumulation buffer.
138         writeIndex = m_accumulationBuffer->accumulate(temporaryBuffer, framesToProcess, &m_accumulationReadIndex, m_postDelayLength);
139     }
140 
141     // Finally copy input to pre-delay.
142     if (m_preDelayLength > 0) {
143         memcpy(preDelayedSource, source, sizeof(float) * framesToProcess);
144         m_preReadWriteIndex += framesToProcess;
145 
146         ASSERT(m_preReadWriteIndex <= m_preDelayLength);
147         if (m_preReadWriteIndex >= m_preDelayLength)
148             m_preReadWriteIndex = 0;
149     }
150 
151     m_framesProcessed += framesToProcess;
152 }
153 
reset()154 void ReverbConvolverStage::reset()
155 {
156     m_convolver->reset();
157     m_preDelayBuffer.zero();
158     m_accumulationReadIndex = 0;
159     m_inputReadIndex = 0;
160     m_framesProcessed = 0;
161 }
162 
163 } // namespace WebCore
164 
165 #endif // ENABLE(WEB_AUDIO)
166