third_party/blink/renderer/modules/webaudio/offline_audio_destination_node.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
 * 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
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 */

#ifndef THIRD_PARTY_BLINK_RENDERER_MODULES_WEBAUDIO_OFFLINE_AUDIO_DESTINATION_NODE_H_
#define THIRD_PARTY_BLINK_RENDERER_MODULES_WEBAUDIO_OFFLINE_AUDIO_DESTINATION_NODE_H_

#include <memory>
#include "base/memory/scoped_refptr.h"
#include "third_party/blink/renderer/modules/webaudio/audio_buffer.h"
#include "third_party/blink/renderer/modules/webaudio/audio_destination_node.h"
#include "third_party/blink/renderer/modules/webaudio/offline_audio_context.h"
#include "third_party/blink/renderer/platform/scheduler/public/thread.h"

namespace blink {

class BaseAudioContext;
class AudioBus;
class OfflineAudioContext;

class OfflineAudioDestinationHandler final : public AudioDestinationHandler {
 public:
  static scoped_refptr<OfflineAudioDestinationHandler> Create(
      AudioNode&,
      unsigned number_of_channels,
      size_t frames_to_process,
      float sample_rate);
  ~OfflineAudioDestinationHandler() override;

  // AudioHandler
  void Dispose() override;
  void Initialize() override;
  void Uninitialize() override;

  // AudioNode
  double TailTime() const override { return 0; }
  double LatencyTime() const override { return 0; }

  OfflineAudioContext* Context() const final;

  // AudioDestinationHandler
  void StartRendering() override;
  void StopRendering() override;
  unsigned long MaxChannelCount() const override;

  void RestartRendering() override;

  double SampleRate() const override { return sample_rate_; }

  size_t RenderQuantumFrames() const {
    return AudioUtilities::kRenderQuantumFrames;
  }

  // This is called when rendering of the offline context is started
  // which will save the rendered audio data in |render_target|.  This
  // allows creation of the AudioBuffer when startRendering is called
  // instead of when the OfflineAudioContext is created.
  void InitializeOfflineRenderThread(AudioBuffer* render_target);
  AudioBuffer* RenderTarget() const { return render_target_.Get(); }

  unsigned NumberOfChannels() const { return number_of_channels_; }

  bool RequiresTailProcessing() const final { return false; }

 private:
  OfflineAudioDestinationHandler(AudioNode&,
                                 unsigned number_of_channels,
                                 size_t frames_to_process,
                                 float sample_rate);

  // Set up the rendering and start. After setting the context up, it will
  // eventually call |doOfflineRendering|.
  void StartOfflineRendering();

  // Suspend the rendering loop and notify the main thread to resolve the
  // associated promise.
  void SuspendOfflineRendering();

  // Start the rendering loop.
  void DoOfflineRendering();

  // Finish the rendering loop and notify the main thread to resolve the
  // promise with the rendered buffer.
  void FinishOfflineRendering();

  // Suspend/completion callbacks for the main thread.
  void NotifySuspend(size_t);
  void NotifyComplete();

  // The offline version of render() method. If the rendering needs to be
  // suspended after checking, this stops the rendering and returns true.
  // Otherwise, it returns false after rendering one quantum.
  bool RenderIfNotSuspended(AudioBus* source_bus,
                            AudioBus* destination_bus,
                            size_t number_of_frames);

  // Prepares a task runner for the rendering based on the operation mode
  // (i.e. non-AudioWorklet or AudioWorklet). This is called when the
  // rendering restarts such as context.resume() after context.suspend().
  // The only possible transition is from the non-AudioWorklet mode to the
  // AudioWorklet mode. Once the AudioWorklet mode is activated, the task runner
  // from AudioWorkletThread will be used until the rendering is finished.
  void PrepareTaskRunnerForRendering();

  // This AudioHandler renders into this AudioBuffer.
  // This Persistent doesn't make a reference cycle including the owner
  // OfflineAudioDestinationNode. It is accessed by both audio and main thread.
  CrossThreadPersistent<AudioBuffer> render_target_;
  // Temporary AudioBus for each render quantum.
  scoped_refptr<AudioBus> render_bus_;

  // These variables are for counting the number of frames for the current
  // progress and the remaining frames to be processed.
  size_t frames_processed_;
  size_t frames_to_process_;

  // This flag is necessary to distinguish the state of the context between
  // 'created' and 'suspended'. If this flag is false and the current state
  // is 'suspended', it means the context is created and have not started yet.
  bool is_rendering_started_;

  unsigned number_of_channels_;
  float sample_rate_;

  // The rendering thread for the non-AudioWorklet mode. For the AudioWorklet
  // node, AudioWorkletThread will drive the rendering.
  std::unique_ptr<Thread> render_thread_;

  scoped_refptr<base::SingleThreadTaskRunner> render_thread_task_runner_;
  scoped_refptr<base::SingleThreadTaskRunner> main_thread_task_runner_;
};

class OfflineAudioDestinationNode final : public AudioDestinationNode {
 public:
  static OfflineAudioDestinationNode* Create(BaseAudioContext*,
                                             unsigned number_of_channels,
                                             size_t frames_to_process,
                                             float sample_rate);

 private:
  OfflineAudioDestinationNode(BaseAudioContext&,
                              unsigned number_of_channels,
                              size_t frames_to_process,
                              float sample_rate);
};

}  // namespace blink

#endif  // THIRD_PARTY_BLINK_RENDERER_MODULES_WEBAUDIO_OFFLINE_AUDIO_DESTINATION_NODE_H_