clipping_predictor_level_buffer.h

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/*

 *  Copyright (c) 2021 The WebRTC project authors. All Rights Reserved.

 *  Use of this source code is governed by a BSD-style license

 *  that can be found in the LICENSE file in the root of the source

 *  tree. An additional intellectual property rights grant can be found

 *  in the file PATENTS.  All contributing project authors may

 *  be found in the AUTHORS file in the root of the source tree.

*/

#ifndef MODULES_AUDIO_PROCESSING_AGC2_CLIPPING_PREDICTOR_LEVEL_BUFFER_H_

#define MODULES_AUDIO_PROCESSING_AGC2_CLIPPING_PREDICTOR_LEVEL_BUFFER_H_

#include <memory>

#include <vector>

#include "absl/types/optional.h"

namespace webrtc {

// A circular buffer to store frame-wise `Level` items for clipping prediction.

// The current implementation is not optimized for large buffer lengths.

class ClippingPredictorLevelBuffer {

 public:

  struct Level {

    float average;

    float max;

    bool operator==(const Level& level) const;

};

  // Recommended maximum capacity. It is possible to create a buffer with a

  // larger capacity, but the implementation is not optimized for large values.

  static constexpr int kMaxCapacity = 100;

  // Ctor. Sets the buffer capacity to max(1, `capacity`) and logs a warning

  // message if the capacity is greater than `kMaxCapacity`.

  explicit ClippingPredictorLevelBuffer(int capacity);

  ~ClippingPredictorLevelBuffer() {}

  ClippingPredictorLevelBuffer(const ClippingPredictorLevelBuffer&) = delete;

  ClippingPredictorLevelBuffer& operator=(const ClippingPredictorLevelBuffer&) =

      delete;

  void Reset();

  // Returns the current number of items stored in the buffer.

  int Size() const { return size_; }

  // Returns the capacity of the buffer.

  int Capacity() const { return data_.size(); }

  // Adds a `level` item into the circular buffer `data_`. Stores at most

  // `Capacity()` items. If more items are pushed, the new item replaces the

  // least recently pushed item.

  void Push(Level level);

  // If at least `num_items` + `delay` items have been pushed, returns the

  // average and maximum value for the `num_items` most recently pushed items

  // from `delay` to `delay` - `num_items` (a delay equal to zero corresponds

  // to the most recently pushed item). The value of `delay` is limited to

  // [0, N] and `num_items` to [1, M] where N + M is the capacity of the buffer.

  absl::optional<Level> ComputePartialMetrics(int delay, int num_items) const;

 private:

  int tail_;

  int size_;

  std::vector<Level> data_;

};

}  // namespace webrtc

#endif  // MODULES_AUDIO_PROCESSING_AGC2_CLIPPING_PREDICTOR_LEVEL_BUFFER_H_