77 lines
2.8 KiB
C++
77 lines
2.8 KiB
C++
/*
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* Copyright (c) 2019 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#ifndef AUDIO_UTILITY_CHANNEL_MIXING_MATRIX_H_
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#define AUDIO_UTILITY_CHANNEL_MIXING_MATRIX_H_
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#include <vector>
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#include "api/audio/channel_layout.h"
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namespace webrtc {
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class ChannelMixingMatrix {
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public:
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ChannelMixingMatrix(ChannelLayout input_layout,
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int input_channels,
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ChannelLayout output_layout,
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int output_channels);
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~ChannelMixingMatrix();
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// Create the transformation matrix of input channels to output channels.
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// Updates the empty matrix with the transformation, and returns true
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// if the transformation is just a remapping of channels (no mixing).
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// The size of |matrix| is |output_channels| x |input_channels|, i.e., the
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// number of rows equals the number of output channels and the number of
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// columns corresponds to the number of input channels.
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// This file is derived from Chromium's media/base/channel_mixing_matrix.h.
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bool CreateTransformationMatrix(std::vector<std::vector<float>>* matrix);
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private:
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const bool use_voip_channel_mapping_adjustments_;
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// Result transformation of input channels to output channels
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std::vector<std::vector<float>>* matrix_;
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// Input and output channel layout provided during construction.
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ChannelLayout input_layout_;
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int input_channels_;
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ChannelLayout output_layout_;
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int output_channels_;
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// Helper variable for tracking which inputs are currently unaccounted,
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// should be empty after construction completes.
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std::vector<Channels> unaccounted_inputs_;
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// Helper methods for managing unaccounted input channels.
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void AccountFor(Channels ch);
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bool IsUnaccounted(Channels ch) const;
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// Helper methods for checking if |ch| exists in either |input_layout_| or
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// |output_layout_| respectively.
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bool HasInputChannel(Channels ch) const;
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bool HasOutputChannel(Channels ch) const;
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// Helper methods for updating |matrix_| with the proper value for
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// mixing |input_ch| into |output_ch|. MixWithoutAccounting() does not
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// remove the channel from |unaccounted_inputs_|.
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void Mix(Channels input_ch, Channels output_ch, float scale);
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void MixWithoutAccounting(Channels input_ch, Channels output_ch, float scale);
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// Delete the copy constructor and assignment operator.
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ChannelMixingMatrix(const ChannelMixingMatrix& other) = delete;
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ChannelMixingMatrix& operator=(const ChannelMixingMatrix& other) = delete;
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};
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} // namespace webrtc
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#endif // AUDIO_UTILITY_CHANNEL_MIXING_MATRIX_H_
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