third_party/WebKit/Source/modules/webaudio/AudioBasicProcessorHandler.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.
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 *    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
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 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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#include "modules/webaudio/AudioBasicProcessorHandler.h"
#include "modules/webaudio/AudioNodeInput.h"
#include "modules/webaudio/AudioNodeOutput.h"
#include "platform/audio/AudioBus.h"
#include "platform/audio/AudioProcessor.h"
#include <memory>

namespace blink {

AudioBasicProcessorHandler::AudioBasicProcessorHandler(
    NodeType nodeType,
    AudioNode& node,
    float sampleRate,
    std::unique_ptr<AudioProcessor> processor)
    : AudioHandler(nodeType, node, sampleRate),
      m_processor(std::move(processor)) {
  addInput();
  addOutput(1);
}

PassRefPtr<AudioBasicProcessorHandler> AudioBasicProcessorHandler::create(
    NodeType nodeType,
    AudioNode& node,
    float sampleRate,
    std::unique_ptr<AudioProcessor> processor) {
  return adoptRef(new AudioBasicProcessorHandler(nodeType, node, sampleRate,
                                                 std::move(processor)));
}

AudioBasicProcessorHandler::~AudioBasicProcessorHandler() {
  // Safe to call the uninitialize() because it's final.
  uninitialize();
}

void AudioBasicProcessorHandler::initialize() {
  if (isInitialized())
    return;

  DCHECK(processor());
  processor()->initialize();

  AudioHandler::initialize();
}

void AudioBasicProcessorHandler::uninitialize() {
  if (!isInitialized())
    return;

  DCHECK(processor());
  processor()->uninitialize();

  AudioHandler::uninitialize();
}

void AudioBasicProcessorHandler::process(size_t framesToProcess) {
  AudioBus* destinationBus = output(0).bus();

  if (!isInitialized() || !processor() ||
      processor()->numberOfChannels() != numberOfChannels()) {
    destinationBus->zero();
  } else {
    AudioBus* sourceBus = input(0).bus();

    // FIXME: if we take "tail time" into account, then we can avoid calling processor()->process() once the tail dies down.
    if (!input(0).isConnected())
      sourceBus->zero();

    processor()->process(sourceBus, destinationBus, framesToProcess);
  }
}

// Nice optimization in the very common case allowing for "in-place" processing
void AudioBasicProcessorHandler::pullInputs(size_t framesToProcess) {
  // Render input stream - suggest to the input to render directly into output bus for in-place processing in process() if possible.
  input(0).pull(output(0).bus(), framesToProcess);
}

// As soon as we know the channel count of our input, we can lazily initialize.
// Sometimes this may be called more than once with different channel counts, in which case we must safely
// uninitialize and then re-initialize with the new channel count.
void AudioBasicProcessorHandler::checkNumberOfChannelsForInput(
    AudioNodeInput* input) {
  DCHECK(context()->isAudioThread());
  ASSERT(context()->isGraphOwner());

  DCHECK_EQ(input, &this->input(0));
  if (input != &this->input(0))
    return;

  DCHECK(processor());
  if (!processor())
    return;

  unsigned numberOfChannels = input->numberOfChannels();

  if (isInitialized() && numberOfChannels != output(0).numberOfChannels()) {
    // We're already initialized but the channel count has changed.
    uninitialize();
  }

  if (!isInitialized()) {
    // This will propagate the channel count to any nodes connected further down the chain...
    output(0).setNumberOfChannels(numberOfChannels);

    // Re-initialize the processor with the new channel count.
    processor()->setNumberOfChannels(numberOfChannels);
    initialize();
  }

  AudioHandler::checkNumberOfChannelsForInput(input);
}

unsigned AudioBasicProcessorHandler::numberOfChannels() {
  return output(0).numberOfChannels();
}

double AudioBasicProcessorHandler::tailTime() const {
  return m_processor->tailTime();
}

double AudioBasicProcessorHandler::latencyTime() const {
  return m_processor->latencyTime();
}

}  // namespace blink