/*
 * Copyright (C) 2010 Google Inc. All rights reserved.
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 * modification, are permitted provided that the following conditions
 * are met:
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 * 1.  Redistributions of source code must retain the above copyright
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 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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#ifndef THIRD_PARTY_BLINK_RENDERER_PLATFORM_AUDIO_REVERB_CONVOLVER_H_
#define THIRD_PARTY_BLINK_RENDERER_PLATFORM_AUDIO_REVERB_CONVOLVER_H_

#include <memory>
#include "third_party/blink/renderer/platform/audio/audio_array.h"
#include "third_party/blink/renderer/platform/audio/direct_convolver.h"
#include "third_party/blink/renderer/platform/audio/fft_convolver.h"
#include "third_party/blink/renderer/platform/audio/reverb_accumulation_buffer.h"
#include "third_party/blink/renderer/platform/audio/reverb_convolver_stage.h"
#include "third_party/blink/renderer/platform/audio/reverb_input_buffer.h"
#include "third_party/blink/renderer/platform/scheduler/public/thread.h"
#include "third_party/blink/renderer/platform/wtf/allocator.h"
#include "third_party/blink/renderer/platform/wtf/vector.h"

namespace blink {

class AudioChannel;

class PLATFORM_EXPORT ReverbConvolver {
  USING_FAST_MALLOC(ReverbConvolver);
  WTF_MAKE_NONCOPYABLE(ReverbConvolver);

 public:
  // maxFFTSize can be adjusted (from say 2048 to 32768) depending on how much
  // precision is necessary.  For certain tweaky de-convolving applications the
  // phase errors add up quickly and lead to non-sensical results with larger
  // FFT sizes and single-precision floats.  In these cases 2048 is a good
  // size.  If not doing multi-threaded convolution, then should not go > 8192.
  ReverbConvolver(AudioChannel* impulse_response,
                  size_t render_slice_size,
                  size_t max_fft_size,
                  size_t convolver_render_phase,
                  bool use_background_threads);
  ~ReverbConvolver();

  void Process(const AudioChannel* source_channel,
               AudioChannel* destination_channel,
               uint32_t frames_to_process);
  void Reset();

  ReverbInputBuffer* InputBuffer() { return &input_buffer_; }

  size_t LatencyFrames() const;

 private:
  void ProcessInBackground();

  Vector<std::unique_ptr<ReverbConvolverStage>> stages_;
  Vector<std::unique_ptr<ReverbConvolverStage>> background_stages_;
  size_t impulse_response_length_;

  ReverbAccumulationBuffer accumulation_buffer_;

  // One or more background threads read from this input buffer which is fed
  // from the realtime thread.
  ReverbInputBuffer input_buffer_;

  // First stage will be of size m_minFFTSize.  Each next stage will be twice as
  // big until we hit m_maxFFTSize.
  size_t min_fft_size_;
  size_t max_fft_size_;

  // But don't exceed this size in the real-time thread (if we're doing
  // background processing).
  size_t max_realtime_fft_size_;

  // Background thread and synchronization
  std::unique_ptr<Thread> background_thread_;
};

}  // namespace blink

#endif  // THIRD_PARTY_BLINK_RENDERER_PLATFORM_AUDIO_REVERB_CONVOLVER_H_