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

/*
 * Copyright (C) 2010, Google Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1.  Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2.  Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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#include "platform/audio/AudioResampler.h"
#include "wtf/MathExtras.h"
#include "wtf/PtrUtil.h"
#include <algorithm>

namespace blink {

const double AudioResampler::MaxRate = 8.0;

AudioResampler::AudioResampler() : m_rate(1.0) {
  m_kernels.append(wrapUnique(new AudioResamplerKernel(this)));
  m_sourceBus = AudioBus::create(1, 0, false);
}

AudioResampler::AudioResampler(unsigned numberOfChannels) : m_rate(1.0) {
  for (unsigned i = 0; i < numberOfChannels; ++i)
    m_kernels.append(wrapUnique(new AudioResamplerKernel(this)));

  m_sourceBus = AudioBus::create(numberOfChannels, 0, false);
}

void AudioResampler::configureChannels(unsigned numberOfChannels) {
  unsigned currentSize = m_kernels.size();
  if (numberOfChannels == currentSize)
    return;  // already setup

  // First deal with adding or removing kernels.
  if (numberOfChannels > currentSize) {
    for (unsigned i = currentSize; i < numberOfChannels; ++i)
      m_kernels.append(wrapUnique(new AudioResamplerKernel(this)));
  } else
    m_kernels.resize(numberOfChannels);

  // Reconfigure our source bus to the new channel size.
  m_sourceBus = AudioBus::create(numberOfChannels, 0, false);
}

void AudioResampler::process(AudioSourceProvider* provider,
                             AudioBus* destinationBus,
                             size_t framesToProcess) {
  ASSERT(provider);
  if (!provider)
    return;

  unsigned numberOfChannels = m_kernels.size();

  // Make sure our configuration matches the bus we're rendering to.
  bool channelsMatch = (destinationBus &&
                        destinationBus->numberOfChannels() == numberOfChannels);
  ASSERT(channelsMatch);
  if (!channelsMatch)
    return;

  // Setup the source bus.
  for (unsigned i = 0; i < numberOfChannels; ++i) {
    // Figure out how many frames we need to get from the provider, and a
    // pointer to the buffer.
    size_t framesNeeded;
    float* fillPointer =
        m_kernels[i]->getSourcePointer(framesToProcess, &framesNeeded);
    ASSERT(fillPointer);
    if (!fillPointer)
      return;

    m_sourceBus->setChannelMemory(i, fillPointer, framesNeeded);
  }

  // Ask the provider to supply the desired number of source frames.
  provider->provideInput(m_sourceBus.get(), m_sourceBus->length());

  // Now that we have the source data, resample each channel into the
  // destination bus.
  // FIXME: optimize for the common stereo case where it's faster to process
  // both left/right channels in the same inner loop.
  for (unsigned i = 0; i < numberOfChannels; ++i) {
    float* destination = destinationBus->channel(i)->mutableData();
    m_kernels[i]->process(destination, framesToProcess);
  }
}

void AudioResampler::setRate(double rate) {
  if (std::isnan(rate) || std::isinf(rate) || rate <= 0.0)
    return;

  m_rate = std::min(AudioResampler::MaxRate, rate);
}

void AudioResampler::reset() {
  unsigned numberOfChannels = m_kernels.size();
  for (unsigned i = 0; i < numberOfChannels; ++i)
    m_kernels[i]->reset();
}

}  // namespace blink