third_party/WebKit/Source/modules/webaudio/AudioDestinationNode.h

/*
 * 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
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGE.
 */

#ifndef AudioDestinationNode_h
#define AudioDestinationNode_h

#include "modules/webaudio/AudioBuffer.h"
#include "modules/webaudio/AudioNode.h"
#include "platform/audio/AudioBus.h"
#include "platform/audio/AudioIOCallback.h"
#include "platform/audio/AudioSourceProvider.h"

namespace blink {

class AudioBus;
class BaseAudioContext;

class AudioDestinationHandler : public AudioHandler, public AudioIOCallback {
 public:
  AudioDestinationHandler(AudioNode&, float sampleRate);
  ~AudioDestinationHandler() override;

  // AudioHandler
  void process(size_t) final {
  }  // we're pulled by hardware so this is never called

  // The audio hardware calls render() to get the next render quantum of audio into destinationBus.
  // It will optionally give us local/live audio input in sourceBus (if it's not 0).
  void render(AudioBus* sourceBus,
              AudioBus* destinationBus,
              size_t numberOfFrames) final;

  size_t currentSampleFrame() const {
    return acquireLoad(&m_currentSampleFrame);
  }
  double currentTime() const {
    return currentSampleFrame() / static_cast<double>(sampleRate());
  }

  virtual unsigned long maxChannelCount() const { return 0; }

  virtual void startRendering() = 0;
  virtual void stopRendering() = 0;

 protected:
  // LocalAudioInputProvider allows us to expose an AudioSourceProvider for local/live audio input.
  // If there is local/live audio input, we call set() with the audio input data every render quantum.
  class LocalAudioInputProvider final : public AudioSourceProvider {
   public:
    LocalAudioInputProvider()
        : m_sourceBus(AudioBus::create(
              2,
              ProcessingSizeInFrames))  // FIXME: handle non-stereo local input.
    {}

    void set(AudioBus* bus) {
      if (bus)
        m_sourceBus->copyFrom(*bus);
    }

    // AudioSourceProvider.
    void provideInput(AudioBus* destinationBus,
                      size_t numberOfFrames) override {
      bool isGood = destinationBus &&
                    destinationBus->length() == numberOfFrames &&
                    m_sourceBus->length() == numberOfFrames;
      DCHECK(isGood);
      if (isGood)
        destinationBus->copyFrom(*m_sourceBus);
    }

   private:
    RefPtr<AudioBus> m_sourceBus;
  };

  // Counts the number of sample-frames processed by the destination.
  size_t m_currentSampleFrame;

  LocalAudioInputProvider m_localAudioInputProvider;
};

class AudioDestinationNode : public AudioNode {
  DEFINE_WRAPPERTYPEINFO();

 public:
  AudioDestinationHandler& audioDestinationHandler() const;

  unsigned long maxChannelCount() const;

 protected:
  AudioDestinationNode(BaseAudioContext&);
};

}  // namespace blink

#endif  // AudioDestinationNode_h