Move usage of QualityScaler to ViEEncoder.

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.
  */
 
 #ifndef WEBRTC_MODULES_VIDEO_CODING_UTILITY_QUALITY_SCALER_H_
 #define WEBRTC_MODULES_VIDEO_CODING_UTILITY_QUALITY_SCALER_H_
 
+#include <utility>
+
 #include "webrtc/common_types.h"
-#include "webrtc/common_video/include/i420_buffer_pool.h"
+#include "webrtc/base/optional.h"
+#include "webrtc/base/sequenced_task_checker.h"
 #include "webrtc/modules/video_coding/utility/moving_average.h"
 
 namespace webrtc {
+
+// An interface for a class that receives scale up/down requests.
+class ScalingObserverInterface {
+ public:
+  enum ScaleReason { kQuality, kCpu };
+  static const size_t kScaleReasonSize = 2;
+  // Called to signal that we can handle larger frames.
+  virtual void ScaleUp(ScaleReason reason) = 0;
+  // Called to signal that encoder to scale down.
+  virtual void ScaleDown(ScaleReason reason) = 0;
+
+ protected:
+  virtual ~ScalingObserverInterface() {}
+};
+
+// QualityScaler runs asynchronously and monitors QP values of encoded frames.
+// It holds a reference to a ScalingObserverInterface implementation to signal
+// an intent to scale up or down.
 class QualityScaler {
  public:
-  struct Resolution {
-    int width;
-    int height;
+  struct QPThresholds {
+    QPThresholds(int l, int h) : low(l), high(h) {}
+    QPThresholds() : low(-1), high(-1) {}
+    int low;
+    int high;
+  };
+  struct Settings {
+    Settings(bool on, int low, int high)
+        : enabled(on),
+          thresholds(rtc::Optional<QPThresholds>(QPThresholds(low, high))) {}
+    explicit Settings(bool on) : enabled(on) {}
+    const bool enabled;
+    const rtc::Optional<QPThresholds> thresholds;
   };
 
-  QualityScaler();
-  void Init(VideoCodecType codec_type,
-            int initial_bitrate_kbps,
-            int width,
-            int height,
-            int fps);
-  void Init(int low_qp_threshold,
-            int high_qp_threshold,
-            int initial_bitrate_kbps,
-            int width,
-            int height,
-            int fps);
-  void ReportFramerate(int framerate);
-  void ReportQP(int qp);
-  void ReportDroppedFrame();
-  void OnEncodeFrame(int width, int height);
-  Resolution GetScaledResolution() const;
-  rtc::scoped_refptr<VideoFrameBuffer> GetScaledBuffer(
-      const rtc::scoped_refptr<VideoFrameBuffer>& frame);
-  int downscale_shift() const { return downscale_shift_; }
+  // Construct a QualityScaler with a given |observer|.
+  // This starts the quality scaler periodically checking what the average QP
+  // has been recently.
+  QualityScaler(ScalingObserverInterface* observer, VideoCodecType codec_type);
+  // If specific thresholds are desired these can be supplied as |thresholds|.
+  QualityScaler(ScalingObserverInterface* observer, QPThresholds thresholds);
+  virtual ~QualityScaler();
+  // Should be called each time the encoder drops a frame
+  void ReportDroppedFrame() const;

[magjed_webrtc, 2016/11/10 13:07:00]

I don't think this function or ReportQP should be const.

[kthelgason, 2016/11/10 15:38:27]

Acknowledged.

+  // Inform the QualityScaler of the last seen QP.
+  void ReportQP(int qp) const;
+
+  // This method declared virtual to help with testing.

[magjed_webrtc, 2016/11/10 13:07:00]

It's not virtual anymore and not used for testing, so make it private.

[kthelgason, 2016/11/10 15:38:27]

Done.

+  int64_t GetSamplingPeriodMs() const;
+
+  // The following members declared protected for testing purposes
+ protected:
+  QualityScaler(ScalingObserverInterface* observer,
+                QPThresholds thresholds,
+                int64_t sampling_period);
 
  private:
+  class CheckQPTask;
+  void CheckQP();
   void ClearSamples();
-  void ScaleUp();
-  void ScaleDown();
-  void UpdateTargetResolution(int width, int height);
+  void ReportQPLow();
+  void ReportQPHigh();
 
-  I420BufferPool pool_;
+  CheckQPTask* check_qp_task_ GUARDED_BY(&task_checker_);
+  ScalingObserverInterface* const observer_ GUARDED_BY(&task_checker_);
+  rtc::SequencedTaskChecker task_checker_;
 
-  size_t num_samples_downscale_;
-  size_t num_samples_upscale_;
-  bool fast_rampup_;
-  MovingAverage average_qp_;
-  MovingAverage framedrop_percent_;
+  int64_t sampling_period_ms_;
+  bool fast_rampup_ GUARDED_BY(&task_checker_);
+  mutable MovingAverage average_qp_ GUARDED_BY(&task_checker_);

[magjed_webrtc, 2016/11/10 13:07:00]

I don't think these should be mutable unless you have a really good reason.

[kthelgason, 2016/11/10 15:38:27]

I made these mutable and the report{QP, DroppedFrame} functions const because I
thought of the MovingAverage as an implementation detail, and the fact that
those functions don't actually change the _observable_ state of the class.

I've changed it back and dropped const from the methods as per your comments, as
I guess it's a matter of interpretation whether they really are const.

+  mutable MovingAverage framedrop_percent_ GUARDED_BY(&task_checker_);
 
-  int low_qp_threshold_;
-  int high_qp_threshold_;
-  Resolution target_res_;
-
-  int downscale_shift_;
-  int maximum_shift_;
+  QPThresholds thresholds_ GUARDED_BY(&task_checker_);
 };
-
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_VIDEO_CODING_UTILITY_QUALITY_SCALER_H_