Make QualityScaler more responsive to downgrades.

webrtc/modules/video_coding/utility/quality_scaler.h

 /*
  *  Copyright (c) 2014 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 12 matching lines @@
     int width;
     int height;
   };
 
   QualityScaler();
   void Init(int low_qp_threshold,
             int high_qp_threshold,
             bool use_framerate_reduction,
             int initial_bitrate_kbps,
             int width,
-            int height);
+            int height,
+            int fps);
   void SetMinResolution(int min_width, int min_height);
   void ReportFramerate(int framerate);
   void ReportQP(int qp);
   void ReportDroppedFrame();
   void Reset(int framerate, int bitrate, int width, int height);
   void OnEncodeFrame(const VideoFrame& frame);
   Resolution GetScaledResolution() const;
   const VideoFrame& GetScaledFrame(const VideoFrame& frame);
   int GetTargetFramerate() const;
   int downscale_shift() const { return downscale_shift_; }
 
  private:
   void AdjustScale(bool up);
   void UpdateTargetResolution(int frame_width, int frame_height);
   void ClearSamples();
+  void UpdateSampleCounts();
 
   Scaler scaler_;
   VideoFrame scaled_frame_;
 
-  size_t num_samples_;
+  size_t num_samples_downscale_;
+  size_t num_samples_upscale_;
+  int measure_seconds_upscale_;
+  MovingAverage<int> average_qp_upscale_;
+  MovingAverage<int> average_qp_downscale_;
+
   int framerate_;
   int target_framerate_;
   int low_qp_threshold_;
   int high_qp_threshold_;
   MovingAverage<int> framedrop_percent_;
-  MovingAverage<int> average_qp_;
   Resolution res_;
 
   int downscale_shift_;
   int framerate_down_;
   bool use_framerate_reduction_;
   int min_width_;
   int min_height_;
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_VIDEO_CODING_UTILITY_QUALITY_SCALER_H_