alignment_mixer.h - mozsearch

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/*

 *  Copyright (c) 2019 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_AEC3_ALIGNMENT_MIXER_H_

#define MODULES_AUDIO_PROCESSING_AEC3_ALIGNMENT_MIXER_H_

#include <vector>

#include "api/array_view.h"

#include "api/audio/echo_canceller3_config.h"

#include "modules/audio_processing/aec3/aec3_common.h"

#include "modules/audio_processing/aec3/block.h"

namespace webrtc {

// Performs channel conversion to mono for the purpose of providing a decent

// mono input for the delay estimation. This is achieved by analyzing all

// incoming channels and produce one single channel output.

class AlignmentMixer {

 public:

  AlignmentMixer(size_t num_channels,

                 const EchoCanceller3Config::Delay::AlignmentMixing& config);

  AlignmentMixer(size_t num_channels,

                 bool downmix,

                 bool adaptive_selection,

                 float excitation_limit,

                 bool prefer_first_two_channels);

  void ProduceOutput(const Block& x, rtc::ArrayView<float, kBlockSize> y);

  enum class MixingVariant { kDownmix, kAdaptive, kFixed };

 private:

  const size_t num_channels_;

  const float one_by_num_channels_;

  const float excitation_energy_threshold_;

  const bool prefer_first_two_channels_;

  const MixingVariant selection_variant_;

  std::array<size_t, 2> strong_block_counters_;

  std::vector<float> cumulative_energies_;

  int selected_channel_ = 0;

  size_t block_counter_ = 0;

  void Downmix(const Block& x, rtc::ArrayView<float, kBlockSize> y) const;

  int SelectChannel(const Block& x);

};

}  // namespace webrtc

#endif  // MODULES_AUDIO_PROCESSING_AEC3_ALIGNMENT_MIXER_H_