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      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 "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 
     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 
     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 
     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 
    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