Roll up of playback rate efficiency improvements for M56.

media/filters/audio_renderer_algorithm.h

Index: media/filters/audio_renderer_algorithm.h
diff --git a/media/filters/audio_renderer_algorithm.h b/media/filters/audio_renderer_algorithm.h
index 398198ab2b81be95c1c0636997103d0b78e00c2c..bad51caecb82f87e6b4272f6dbba988edaa786e4 100644
--- a/media/filters/audio_renderer_algorithm.h
+++ b/media/filters/audio_renderer_algorithm.h
@@ -24,6 +24,7 @@
 #include <stdint.h>
 
 #include <memory>
+#include <vector>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
@@ -43,6 +44,17 @@ class MEDIA_EXPORT AudioRendererAlgorithm {
   // Initializes this object with information about the audio stream.
   void Initialize(const AudioParameters& params);
 
+  // Allows clients to specify which channels will be considered by the
+  // algorithm when adapting for playback rate, other channels will be muted.
+  // Useful to avoid performance overhead of the adapatation algorithm. Must
+  // only be called after Initialize(); may be called multiple times if the
+  // mask changes.
+  //
+  // E.g., If |channel_mask| is [true, false] only the first channel will be
+  // used to construct the playback rate adapated signal. This is useful if
+  // channel upmixing has been performed prior to this point.
+  void SetChannelMask(std::vector<bool> channel_mask);
+
   // Tries to fill |requested_frames| frames into |dest| with possibly scaled
   // data from our |audio_buffer_|. Data is scaled based on |playback_rate|,
   // using a variation of the Overlap-Add method to combine sample windows.
@@ -84,6 +96,8 @@ class MEDIA_EXPORT AudioRendererAlgorithm {
   // Returns the samples per second for this audio stream.
   int samples_per_second() { return samples_per_second_; }
 
+  std::vector<bool> channel_mask_for_testing() { return channel_mask_; }
+
  private:
   // Within |search_block_|, find the block of data that is most similar to
   // |target_block_|, and write it in |optimal_block_|. This method assumes that
@@ -128,6 +142,11 @@ class MEDIA_EXPORT AudioRendererAlgorithm {
   // Converts a time in milliseconds to frames using |samples_per_second_|.
   int ConvertMillisecondsToFrames(int ms) const;
 
+  // Creates or recreates |target_block_wrapper_| and |search_block_wrapper_|
+  // after a |channel_mask_| change. May be called at anytime after a channel
+  // mask has been specified.
+  void CreateSearchWrappers();
+
   // Number of channels in audio stream.
   int channels_;
 
@@ -207,6 +226,13 @@ class MEDIA_EXPORT AudioRendererAlgorithm {
   // |target_block_|.
   std::unique_ptr<AudioBus> target_block_;
 
+  // Active channels to consider while searching. Used to speed up WSOLA
+  // processing by ignoring always muted channels. Wrappers are always
+  // constructed during Initialize() and have <= |channels_|.
+  std::vector<bool> channel_mask_;
+  std::unique_ptr<AudioBus> search_block_wrapper_;
+  std::unique_ptr<AudioBus> target_block_wrapper_;
+
   // The initial and maximum capacity calculated by Initialize().
   int initial_capacity_;
   int max_capacity_;