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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.
#include <vector>
#include "api/audio/channel_layout.h"
namespace webrtc {
class ChannelMixingMatrix {
ChannelMixingMatrix(ChannelLayout input_layout,
int input_channels,
ChannelLayout output_layout,
int output_channels);
// Create the transformation matrix of input channels to output channels.
// Updates the empty matrix with the transformation, and returns true
// if the transformation is just a remapping of channels (no mixing).
// The size of |matrix| is |output_channels| x |input_channels|, i.e., the
// number of rows equals the number of output channels and the number of
// columns corresponds to the number of input channels.
// This file is derived from Chromium's media/base/channel_mixing_matrix.h.
bool CreateTransformationMatrix(std::vector<std::vector<float>>* matrix);
const bool use_voip_channel_mapping_adjustments_;
// Result transformation of input channels to output channels
std::vector<std::vector<float>>* matrix_;
// Input and output channel layout provided during construction.
ChannelLayout input_layout_;
int input_channels_;
ChannelLayout output_layout_;
int output_channels_;
// Helper variable for tracking which inputs are currently unaccounted,
// should be empty after construction completes.
std::vector<Channels> unaccounted_inputs_;
// Helper methods for managing unaccounted input channels.
void AccountFor(Channels ch);
bool IsUnaccounted(Channels ch) const;
// Helper methods for checking if |ch| exists in either |input_layout_| or
// |output_layout_| respectively.
bool HasInputChannel(Channels ch) const;
bool HasOutputChannel(Channels ch) const;
// Helper methods for updating |matrix_| with the proper value for
// mixing |input_ch| into |output_ch|. MixWithoutAccounting() does not
// remove the channel from |unaccounted_inputs_|.
void Mix(Channels input_ch, Channels output_ch, float scale);
void MixWithoutAccounting(Channels input_ch, Channels output_ch, float scale);
// Delete the copy constructor and assignment operator.
ChannelMixingMatrix(const ChannelMixingMatrix& other) = delete;
ChannelMixingMatrix& operator=(const ChannelMixingMatrix& other) = delete;
} // namespace webrtc