tor-browser

The Tor Browser
git clone https://git.dasho.dev/tor-browser.git
Log | Files | Refs | README | LICENSE

FFTConvolver.cpp (4628B)

      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 "FFTConvolver.h"
     30 
     31 #include "mozilla/PodOperations.h"
     32 
     33 using namespace mozilla;
     34 
     35 namespace WebCore {
     36 
     37 FFTConvolver::FFTConvolver(size_t fftSize, size_t renderPhase)
     38    : m_frame(fftSize), m_readWriteIndex(renderPhase % (fftSize / 2)) {
     39  MOZ_ASSERT(fftSize >= 2 * WEBAUDIO_BLOCK_SIZE);
     40  m_inputBuffer.SetLength(fftSize);
     41  PodZero(m_inputBuffer.Elements(), fftSize);
     42  m_outputBuffer.SetLength(fftSize);
     43  PodZero(m_outputBuffer.Elements(), fftSize);
     44  m_lastOverlapBuffer.SetLength(fftSize / 2);
     45  PodZero(m_lastOverlapBuffer.Elements(), fftSize / 2);
     46 }
     47 
     48 size_t FFTConvolver::sizeOfExcludingThis(
     49    mozilla::MallocSizeOf aMallocSizeOf) const {
     50  size_t amount = 0;
     51  amount += m_frame.SizeOfExcludingThis(aMallocSizeOf);
     52  amount += m_inputBuffer.ShallowSizeOfExcludingThis(aMallocSizeOf);
     53  amount += m_outputBuffer.ShallowSizeOfExcludingThis(aMallocSizeOf);
     54  amount += m_lastOverlapBuffer.ShallowSizeOfExcludingThis(aMallocSizeOf);
     55  return amount;
     56 }
     57 
     58 size_t FFTConvolver::sizeOfIncludingThis(
     59    mozilla::MallocSizeOf aMallocSizeOf) const {
     60  return aMallocSizeOf(this) + sizeOfExcludingThis(aMallocSizeOf);
     61 }
     62 
     63 const float* FFTConvolver::process(FFTBlock* fftKernel, const float* sourceP) {
     64  size_t halfSize = fftSize() / 2;
     65 
     66  // WEBAUDIO_BLOCK_SIZE must be an exact multiple of halfSize,
     67  // halfSize must be a multiple of WEBAUDIO_BLOCK_SIZE
     68  // and > WEBAUDIO_BLOCK_SIZE.
     69  MOZ_ASSERT(halfSize % WEBAUDIO_BLOCK_SIZE == 0 &&
     70             WEBAUDIO_BLOCK_SIZE <= halfSize);
     71 
     72  // Copy samples to input buffer (note contraint above!)
     73  float* inputP = m_inputBuffer.Elements();
     74 
     75  MOZ_ASSERT(sourceP && inputP &&
     76             m_readWriteIndex + WEBAUDIO_BLOCK_SIZE <= m_inputBuffer.Length());
     77 
     78  memcpy(inputP + m_readWriteIndex, sourceP,
     79         sizeof(float) * WEBAUDIO_BLOCK_SIZE);
     80 
     81  float* outputP = m_outputBuffer.Elements();
     82  m_readWriteIndex += WEBAUDIO_BLOCK_SIZE;
     83 
     84  // Check if it's time to perform the next FFT
     85  if (m_readWriteIndex == halfSize) {
     86    // The input buffer is now filled (get frequency-domain version)
     87    m_frame.PerformFFT(m_inputBuffer.Elements());
     88    m_frame.Multiply(*fftKernel);
     89    m_frame.GetInverse(m_outputBuffer.Elements());
     90 
     91    // Overlap-add 1st half from previous time
     92    AudioBufferAddWithScale(m_lastOverlapBuffer.Elements(), 1.0f,
     93                            m_outputBuffer.Elements(), halfSize);
     94 
     95    // Finally, save 2nd half of result
     96    MOZ_ASSERT(m_outputBuffer.Length() == 2 * halfSize &&
     97               m_lastOverlapBuffer.Length() == halfSize);
     98 
     99    memcpy(m_lastOverlapBuffer.Elements(), m_outputBuffer.Elements() + halfSize,
    100           sizeof(float) * halfSize);
    101 
    102    // Reset index back to start for next time
    103    m_readWriteIndex = 0;
    104  }
    105 
    106  return outputP + m_readWriteIndex;
    107 }
    108 
    109 void FFTConvolver::reset() {
    110  PodZero(m_lastOverlapBuffer.Elements(), m_lastOverlapBuffer.Length());
    111  m_readWriteIndex = 0;
    112 }
    113 
    114 size_t FFTConvolver::latencyFrames() const {
    115  return std::max<size_t>(fftSize() / 2, WEBAUDIO_BLOCK_SIZE) -
    116         WEBAUDIO_BLOCK_SIZE;
    117 }
    118 
    119 }  // namespace WebCore