Index: media/base/channel_mixing_matrix.h |
diff --git a/media/base/channel_mixing_matrix.h b/media/base/channel_mixing_matrix.h |
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+// 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_ |