third_party/WebKit/Source/modules/webaudio/ScriptProcessorNode.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
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 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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 */

#ifndef ScriptProcessorNode_h
#define ScriptProcessorNode_h

#include "base/gtest_prod_util.h"
#include "bindings/core/v8/ActiveScriptWrappable.h"
#include "modules/webaudio/AudioNode.h"
#include "platform/audio/AudioBus.h"
#include "wtf/Forward.h"
#include "wtf/PassRefPtr.h"
#include "wtf/RefPtr.h"
#include "wtf/Vector.h"

namespace blink {

class BaseAudioContext;
class AudioBuffer;
class WaitableEvent;

// ScriptProcessorNode is an AudioNode which allows for arbitrary synthesis or processing directly using JavaScript.
// The API allows for a variable number of inputs and outputs, although it must have at least one input or output.
// This basic implementation supports no more than one input and output.
// The "onaudioprocess" attribute is an event listener which will get called periodically with an AudioProcessingEvent which has
// AudioBuffers for each input and output.

class ScriptProcessorHandler final : public AudioHandler {
 public:
  static PassRefPtr<ScriptProcessorHandler> create(
      AudioNode&,
      float sampleRate,
      size_t bufferSize,
      unsigned numberOfInputChannels,
      unsigned numberOfOutputChannels);
  ~ScriptProcessorHandler() override;

  // AudioHandler
  void process(size_t framesToProcess) override;
  void initialize() override;

  size_t bufferSize() const { return m_bufferSize; }

  void setChannelCount(unsigned long, ExceptionState&) override;
  void setChannelCountMode(const String&, ExceptionState&) override;

  virtual unsigned numberOfOutputChannels() const {
    return m_numberOfOutputChannels;
  }

 private:
  ScriptProcessorHandler(AudioNode&,
                         float sampleRate,
                         size_t bufferSize,
                         unsigned numberOfInputChannels,
                         unsigned numberOfOutputChannels);
  double tailTime() const override;
  double latencyTime() const override;

  void fireProcessEvent(unsigned);
  void fireProcessEventForOfflineAudioContext(unsigned, WaitableEvent*);

  // Double buffering
  unsigned doubleBufferIndex() const { return m_doubleBufferIndex; }
  void swapBuffers() { m_doubleBufferIndex = 1 - m_doubleBufferIndex; }
  unsigned m_doubleBufferIndex;

  // These Persistent don't make reference cycles including the owner
  // ScriptProcessorNode.
  PersistentHeapVector<Member<AudioBuffer>> m_inputBuffers;
  PersistentHeapVector<Member<AudioBuffer>> m_outputBuffers;

  size_t m_bufferSize;
  unsigned m_bufferReadWriteIndex;

  unsigned m_numberOfInputChannels;
  unsigned m_numberOfOutputChannels;

  RefPtr<AudioBus> m_internalInputBus;
  // Synchronize process() with fireProcessEvent().
  mutable Mutex m_processEventLock;

  FRIEND_TEST_ALL_PREFIXES(ScriptProcessorNodeTest, BufferLifetime);
};

class ScriptProcessorNode final : public AudioNode,
                                  public ActiveScriptWrappable {
  DEFINE_WRAPPERTYPEINFO();
  USING_GARBAGE_COLLECTED_MIXIN(ScriptProcessorNode);

 public:
  // bufferSize must be one of the following values: 256, 512, 1024, 2048,
  // 4096, 8192, 16384.
  // This value controls how frequently the onaudioprocess event handler is
  // called and how many sample-frames need to be processed each call.
  // Lower numbers for bufferSize will result in a lower (better)
  // latency. Higher numbers will be necessary to avoid audio breakup and
  // glitches.
  // The value chosen must carefully balance between latency and audio quality.
  static ScriptProcessorNode* create(BaseAudioContext&, ExceptionState&);
  static ScriptProcessorNode* create(BaseAudioContext&,
                                     size_t bufferSize,
                                     ExceptionState&);
  static ScriptProcessorNode* create(BaseAudioContext&,
                                     size_t bufferSize,
                                     unsigned numberOfInputChannels,
                                     ExceptionState&);
  static ScriptProcessorNode* create(BaseAudioContext&,
                                     size_t bufferSize,
                                     unsigned numberOfInputChannels,
                                     unsigned numberOfOutputChannels,
                                     ExceptionState&);

  DEFINE_ATTRIBUTE_EVENT_LISTENER(audioprocess);
  size_t bufferSize() const;

  // ScriptWrappable
  bool hasPendingActivity() const final;

  DEFINE_INLINE_VIRTUAL_TRACE() { AudioNode::trace(visitor); }

 private:
  ScriptProcessorNode(BaseAudioContext&,
                      float sampleRate,
                      size_t bufferSize,
                      unsigned numberOfInputChannels,
                      unsigned numberOfOutputChannels);
};

}  // namespace blink

#endif  // ScriptProcessorNode_h