// Copyright (c) 2012 The Chromium Authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. #ifndef MEDIA_BASE_CHANNEL_MIXING_MATRIX_H_ #define MEDIA_BASE_CHANNEL_MIXING_MATRIX_H_ #include #include "base/memory/raw_ptr.h" #include "media/base/channel_layout.h" #include "media/base/media_export.h" namespace media { class MEDIA_EXPORT ChannelMixingMatrix { public: ChannelMixingMatrix(ChannelLayout input_layout, int input_channels, ChannelLayout output_layout, int output_channels); ChannelMixingMatrix(const ChannelMixingMatrix&) = delete; ChannelMixingMatrix& operator=(const ChannelMixingMatrix&) = delete; ~ChannelMixingMatrix(); // 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). bool CreateTransformationMatrix(std::vector>* matrix); private: // Result transformation of input channels to output channels raw_ptr>> 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 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); }; } // namespace media #endif // MEDIA_BASE_CHANNEL_MIXING_MATRIX_H_