third_party/WebKit/Source/platform/audio/ReverbConvolverStage.cpp

/*
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#include "platform/audio/ReverbAccumulationBuffer.h"
#include "platform/audio/ReverbConvolver.h"
#include "platform/audio/ReverbConvolverStage.h"
#include "platform/audio/ReverbInputBuffer.h"
#include "platform/audio/VectorMath.h"
#include "wtf/PtrUtil.h"

namespace blink {

using namespace VectorMath;

ReverbConvolverStage::ReverbConvolverStage(
    const float* impulseResponse,
    size_t,
    size_t reverbTotalLatency,
    size_t stageOffset,
    size_t stageLength,
    size_t fftSize,
    size_t renderPhase,
    size_t renderSliceSize,
    ReverbAccumulationBuffer* accumulationBuffer,
    bool directMode)
    : m_accumulationBuffer(accumulationBuffer),
      m_accumulationReadIndex(0),
      m_inputReadIndex(0),
      m_directMode(directMode) {
  ASSERT(impulseResponse);
  ASSERT(accumulationBuffer);

  if (!m_directMode) {
    m_fftKernel = wrapUnique(new FFTFrame(fftSize));
    m_fftKernel->doPaddedFFT(impulseResponse + stageOffset, stageLength);
    m_fftConvolver = wrapUnique(new FFTConvolver(fftSize));
  } else {
    ASSERT(!stageOffset);
    ASSERT(stageLength <= fftSize / 2);

    m_directKernel = wrapUnique(new AudioFloatArray(fftSize / 2));
    m_directKernel->copyToRange(impulseResponse, 0, stageLength);
    m_directConvolver = wrapUnique(new DirectConvolver(renderSliceSize));
  }
  m_temporaryBuffer.allocate(renderSliceSize);

  // The convolution stage at offset stageOffset needs to have a corresponding
  // delay to cancel out the offset.
  size_t totalDelay = stageOffset + reverbTotalLatency;

  // But, the FFT convolution itself incurs fftSize / 2 latency, so subtract
  // this out...
  size_t halfSize = fftSize / 2;
  if (!m_directMode) {
    ASSERT(totalDelay >= halfSize);
    if (totalDelay >= halfSize)
      totalDelay -= halfSize;
  }

  // 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.  This is
  // coordinated with the other stages, so they don't all do their FFTs at the
  // same time...
  int maxPreDelayLength = std::min(halfSize, totalDelay);
  m_preDelayLength = totalDelay > 0 ? renderPhase % maxPreDelayLength : 0;
  if (m_preDelayLength > totalDelay)
    m_preDelayLength = 0;

  m_postDelayLength = totalDelay - m_preDelayLength;
  m_preReadWriteIndex = 0;
  m_framesProcessed = 0;  // total frames processed so far

  size_t delayBufferSize =
      m_preDelayLength < fftSize ? fftSize : m_preDelayLength;
  delayBufferSize =
      delayBufferSize < renderSliceSize ? renderSliceSize : delayBufferSize;
  m_preDelayBuffer.allocate(delayBufferSize);
}

void ReverbConvolverStage::processInBackground(ReverbConvolver* convolver,
                                               size_t framesToProcess) {
  ReverbInputBuffer* inputBuffer = convolver->inputBuffer();
  float* source =
      inputBuffer->directReadFrom(&m_inputReadIndex, framesToProcess);
  process(source, framesToProcess);
}

void ReverbConvolverStage::process(const float* source,
                                   size_t framesToProcess) {
  ASSERT(source);
  if (!source)
    return;

  // Deal with pre-delay stream : note special handling of zero delay.

  const float* preDelayedSource;
  float* preDelayedDestination;
  float* temporaryBuffer;
  bool isTemporaryBufferSafe = false;
  if (m_preDelayLength > 0) {
    // Handles both the read case (call to process() ) and the write case
    // (memcpy() )
    bool isPreDelaySafe =
        m_preReadWriteIndex + framesToProcess <= m_preDelayBuffer.size();
    ASSERT(isPreDelaySafe);
    if (!isPreDelaySafe)
      return;

    isTemporaryBufferSafe = framesToProcess <= m_temporaryBuffer.size();

    preDelayedDestination = m_preDelayBuffer.data() + m_preReadWriteIndex;
    preDelayedSource = preDelayedDestination;
    temporaryBuffer = m_temporaryBuffer.data();
  } else {
    // Zero delay
    preDelayedDestination = 0;
    preDelayedSource = source;
    temporaryBuffer = m_preDelayBuffer.data();

    isTemporaryBufferSafe = framesToProcess <= m_preDelayBuffer.size();
  }

  ASSERT(isTemporaryBufferSafe);
  if (!isTemporaryBufferSafe)
    return;

  if (m_framesProcessed < m_preDelayLength) {
    // For the first m_preDelayLength frames don't process the convolver,
    // instead simply buffer in the pre-delay.  But while buffering the
    // pre-delay, we still need to update our index.
    m_accumulationBuffer->updateReadIndex(&m_accumulationReadIndex,
                                          framesToProcess);
  } else {
    // Now, run the convolution (into the delay buffer).
    // An expensive FFT will happen every fftSize / 2 frames.
    // We process in-place here...
    if (!m_directMode)
      m_fftConvolver->process(m_fftKernel.get(), preDelayedSource,
                              temporaryBuffer, framesToProcess);
    else
      m_directConvolver->process(m_directKernel.get(), preDelayedSource,
                                 temporaryBuffer, framesToProcess);

    // Now accumulate into reverb's accumulation buffer.
    m_accumulationBuffer->accumulate(temporaryBuffer, framesToProcess,
                                     &m_accumulationReadIndex,
                                     m_postDelayLength);
  }

  // Finally copy input to pre-delay.
  if (m_preDelayLength > 0) {
    memcpy(preDelayedDestination, source, sizeof(float) * framesToProcess);
    m_preReadWriteIndex += framesToProcess;

    ASSERT(m_preReadWriteIndex <= m_preDelayLength);
    if (m_preReadWriteIndex >= m_preDelayLength)
      m_preReadWriteIndex = 0;
  }

  m_framesProcessed += framesToProcess;
}

void ReverbConvolverStage::reset() {
  if (!m_directMode)
    m_fftConvolver->reset();
  else
    m_directConvolver->reset();
  m_preDelayBuffer.zero();
  m_accumulationReadIndex = 0;
  m_inputReadIndex = 0;
  m_framesProcessed = 0;
}

}  // namespace blink