| // 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 <vector> |
| |
| #include "base/macros.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(); |
| |
| // 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<std::vector<float>>* matrix); |
| |
| private: |
| // 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); |
| |
| DISALLOW_COPY_AND_ASSIGN(ChannelMixingMatrix); |
| }; |
| |
| } // namespace media |
| |
| #endif // MEDIA_BASE_CHANNEL_MIXING_MATRIX_H_ |