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

/*
 * Copyright (C) 2011, 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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 * DAMAGE.
 */

#ifndef MediaElementAudioSourceNode_h
#define MediaElementAudioSourceNode_h

#include "modules/webaudio/AudioSourceNode.h"
#include "platform/audio/AudioSourceProviderClient.h"
#include "platform/audio/MultiChannelResampler.h"
#include "wtf/PassRefPtr.h"
#include "wtf/ThreadingPrimitives.h"
#include <memory>

namespace blink {

class BaseAudioContext;
class HTMLMediaElement;
class MediaElementAudioSourceOptions;

class MediaElementAudioSourceHandler final : public AudioHandler {
 public:
  static PassRefPtr<MediaElementAudioSourceHandler> create(AudioNode&,
                                                           HTMLMediaElement&);
  ~MediaElementAudioSourceHandler() override;

  HTMLMediaElement* mediaElement() { return m_mediaElement.get(); }

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

  // Helpers for AudioSourceProviderClient implementation of
  // MediaElementAudioSourceNode.
  void setFormat(size_t numberOfChannels, float sampleRate);
  void onCurrentSrcChanged(const KURL& currentSrc);
  void lock();
  void unlock();

 private:
  MediaElementAudioSourceHandler(AudioNode&, HTMLMediaElement&);
  // As an audio source, we will never propagate silence.
  bool propagatesSilence() const override { return false; }

  // Must be called only on the audio thread.
  bool passesCORSAccessCheck();

  // Must be called only on the main thread.
  bool passesCurrentSrcCORSAccessCheck(const KURL& currentSrc);

  // Print warning if CORS restrictions cause MediaElementAudioSource to output zeroes.
  void printCORSMessage(const String& message);

  // This Persistent doesn't make a reference cycle. The reference from
  // HTMLMediaElement to AudioSourceProvideClient, which
  // MediaElementAudioSourceNode implements, is weak.
  Persistent<HTMLMediaElement> m_mediaElement;
  Mutex m_processLock;

  unsigned m_sourceNumberOfChannels;
  double m_sourceSampleRate;

  std::unique_ptr<MultiChannelResampler> m_multiChannelResampler;

  // |m_passesCurrentSrcCORSAccessCheck| holds the value of
  // context()->getSecurityOrigin() && context()->getSecurityOrigin()->canRequest(mediaElement()->currentSrc()),
  // updated in the ctor and onCurrentSrcChanged() on the main thread and
  // used in passesCORSAccessCheck() on the audio thread,
  // protected by |m_processLock|.
  bool m_passesCurrentSrcCORSAccessCheck;

  // Indicates if we need to print a CORS message if the current source has changed and we have no
  // access to it. Must be protected by |m_processLock|.
  bool m_maybePrintCORSMessage;

  // The value of mediaElement()->currentSrc().string() in the ctor and onCurrentSrcChanged().
  // Protected by |m_processLock|.
  String m_currentSrcString;
};

class MediaElementAudioSourceNode final : public AudioSourceNode,
                                          public AudioSourceProviderClient {
  DEFINE_WRAPPERTYPEINFO();
  USING_GARBAGE_COLLECTED_MIXIN(MediaElementAudioSourceNode);

 public:
  static MediaElementAudioSourceNode* create(BaseAudioContext&,
                                             HTMLMediaElement&,
                                             ExceptionState&);
  static MediaElementAudioSourceNode* create(
      BaseAudioContext*,
      const MediaElementAudioSourceOptions&,
      ExceptionState&);

  DECLARE_VIRTUAL_TRACE();
  MediaElementAudioSourceHandler& mediaElementAudioSourceHandler() const;

  HTMLMediaElement* mediaElement() const;

  // AudioSourceProviderClient functions:
  void setFormat(size_t numberOfChannels, float sampleRate) override;
  void onCurrentSrcChanged(const KURL& currentSrc) override;
  void lock() override;
  void unlock() override;

 private:
  MediaElementAudioSourceNode(BaseAudioContext&, HTMLMediaElement&);
};

}  // namespace blink

#endif  // MediaElementAudioSourceNode_h