Transparency improvements in the echo canceller 3

webrtc/modules/audio_processing/aec3/subtractor.h

 /*
  *  Copyright (c) 2017 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 27 matching lines @@
 
   // Performs the echo subtraction.
   void Process(const RenderBuffer& render_buffer,
                const rtc::ArrayView<const float> capture,
                const RenderSignalAnalyzer& render_signal_analyzer,
                const AecState& aec_state,
                SubtractorOutput* output);
 
   void HandleEchoPathChange(const EchoPathVariability& echo_path_variability);
 
-  // Returns the block-wise frequency response of the main adaptive filter.
+  // Returns the block-wise frequency response for the main adaptive filter.
   const std::vector<std::array<float, kFftLengthBy2Plus1>>&
   FilterFrequencyResponse() const {
     return main_filter_.FilterFrequencyResponse();
   }
 
+  // Returns the estimate of the impulse response for the main adaptive filter.
+  const std::array<float, kAdaptiveFilterTimeDomainLength>&
+  FilterImpulseResponse() const {
+    return main_filter_.FilterImpulseResponse();
+  }
+
  private:
   const Aec3Fft fft_;
   ApmDataDumper* data_dumper_;
   const Aec3Optimization optimization_;
   AdaptiveFirFilter main_filter_;
   AdaptiveFirFilter shadow_filter_;
   MainFilterUpdateGain G_main_;
   ShadowFilterUpdateGain G_shadow_;
 
   RTC_DISALLOW_IMPLICIT_CONSTRUCTORS(Subtractor);
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_AUDIO_PROCESSING_AEC3_SUBTRACTOR_H_