TWCC-PLR -based FecController doesn’t need smoothing

webrtc/common_audio/smoothing_filter.h

 /*
  *  Copyright (c) 2016 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 50 matching lines @@
 
   rtc::Optional<int64_t> init_end_time_ms_;
   float last_sample_;
   float alpha_;
   float state_;
   int64_t last_state_time_ms_;
 
   RTC_DISALLOW_IMPLICIT_CONSTRUCTORS(SmoothingFilterImpl);
 };
 
+class NullSmoothingFilter final : public SmoothingFilter {

[minyue-webrtc, 2017/03/22 09:40:55]

can we move NullSmoothingFilter to fec controller
? It is very special and used only there.

[elad.alon_webrtc.org, 2017/03/22 10:14:25]

That's possible. On the other hand, what if somebody else reinvents it in
another file, because it wasn't very visible? Or if someone else needs it, he
would have to move it here. Wouldn't it be best to keep it here to begin with?

+ public:
+  NullSmoothingFilter();
+  ~NullSmoothingFilter() override;
+  void AddSample(float sample) override;
+  rtc::Optional<float> GetAverage() override;
+  bool SetTimeConstantMs(int time_constant_ms) override;
+
+ private:
+  rtc::Optional<float> last_sample_;
+};
+
 }  // namespace webrtc
 
 #endif  // WEBRTC_COMMON_AUDIO_SMOOTHING_FILTER_H_