Added first version of the EchoControl interface, used for AEC abstraction.

Bug: webrtc:8346
Change-Id: I792a5f8eefb98388de199fea12c017759fdc6c1e
Reviewed-on: https://webrtc-review.googlesource.com/6780
Reviewed-by: Per Åhgren <peah@webrtc.org>
Commit-Queue: Gustaf Ullberg <gustaf@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20174}

modules/audio_processing/aec3/echo_canceller3.h

@@ -60,7 +60,7 @@ class Aec3RenderQueueItemVerifier {
 //
 // The class is supposed to be used in a non-concurrent manner apart from the
 // AnalyzeRender call which can be called concurrently with the other methods.
-class EchoCanceller3 {
+class EchoCanceller3 : public EchoControl {
  public:
   // Normal c-tor to use.
   EchoCanceller3(const AudioProcessing::Config::EchoCanceller3& config,
@@ -70,15 +70,15 @@ class EchoCanceller3 {
   EchoCanceller3(int sample_rate_hz,
                  bool use_highpass_filter,
                  std::unique_ptr<BlockProcessor> block_processor);
-  ~EchoCanceller3();
+  ~EchoCanceller3() override;
   // Analyzes and stores an internal copy of the split-band domain render
   // signal.
-  void AnalyzeRender(AudioBuffer* farend);
+  void AnalyzeRender(AudioBuffer* farend) override;
   // Analyzes the full-band domain capture signal to detect signal saturation.
-  void AnalyzeCapture(AudioBuffer* capture);
+  void AnalyzeCapture(AudioBuffer* capture) override;
   // Processes the split-band domain capture signal in order to remove any echo
   // present in the signal.
-  void ProcessCapture(AudioBuffer* capture, bool level_change);
+  void ProcessCapture(AudioBuffer* capture, bool level_change) override;
 
   // Signals whether an external detector has detected echo leakage from the
   // echo canceller.

modules/audio_processing/audio_processing_impl.cc

@@ -302,7 +302,7 @@ struct AudioProcessingImpl::ApmPrivateSubmodules {
   std::unique_ptr<LowCutFilter> low_cut_filter;
   std::unique_ptr<LevelController> level_controller;
   std::unique_ptr<ResidualEchoDetector> residual_echo_detector;
-  std::unique_ptr<EchoCanceller3> echo_canceller3;
+  std::unique_ptr<EchoControl> echo_canceller3;
   std::unique_ptr<PostProcessing> capture_post_processor;
 };
 

modules/audio_processing/include/audio_processing.h

@@ -939,6 +939,21 @@ class EchoControlMobile {
   virtual ~EchoControlMobile() {}
 };
 
+// Interface for an acoustic echo cancellation (AEC) submodule.
+class EchoControl {
+ public:
+  // Analysis (not changing) of the render signal.
+  virtual void AnalyzeRender(AudioBuffer* render) = 0;
+
+  // Analysis (not changing) of the capture signal.
+  virtual void AnalyzeCapture(AudioBuffer* capture) = 0;
+
+  // Processes the capture signal in order to remove the echo.
+  virtual void ProcessCapture(AudioBuffer* capture, bool echo_path_change) = 0;
+
+  virtual ~EchoControl() {}
+};
+
 // The automatic gain control (AGC) component brings the signal to an
 // appropriate range. This is done by applying a digital gain directly and, in
 // the analog mode, prescribing an analog gain to be applied at the audio HAL.