Moving src/webrtc into src/.

In order to eliminate the WebRTC Subtree mirror in Chromium, 
WebRTC is moving the content of the src/webrtc directory up
to the src/ directory.

NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
TBR=tommi@webrtc.org

Bug: chromium:611808
Change-Id: Iac59c5b51b950f174119565bac87955a7994bc38
Reviewed-on: https://webrtc-review.googlesource.com/1560
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Henrik Kjellander <kjellander@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#19845}

modules/video_coding/utility/frame_dropper.h

@@ -0,0 +1,99 @@
+/*
+ *  Copyright (c) 2011 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_FRAME_DROPPER_H_
+#define WEBRTC_MODULES_VIDEO_CODING_UTILITY_FRAME_DROPPER_H_
+
+#include <cstddef>
+
+#include "webrtc/rtc_base/numerics/exp_filter.h"
+#include "webrtc/typedefs.h"
+
+namespace webrtc {
+
+// The Frame Dropper implements a variant of the leaky bucket algorithm
+// for keeping track of when to drop frames to avoid bit rate
+// over use when the encoder can't keep its bit rate.
+class FrameDropper {
+ public:
+  FrameDropper();
+  explicit FrameDropper(float max_time_drops);
+  virtual ~FrameDropper() {}
+
+  // Resets the FrameDropper to its initial state.
+  // This means that the frameRateWeight is set to its
+  // default value as well.
+  virtual void Reset();
+
+  virtual void Enable(bool enable);
+  // Answers the question if it's time to drop a frame
+  // if we want to reach a given frame rate. Must be
+  // called for every frame.
+  //
+  // Return value     : True if we should drop the current frame
+  virtual bool DropFrame();
+  // Updates the FrameDropper with the size of the latest encoded
+  // frame. The FrameDropper calculates a new drop ratio (can be
+  // seen as the probability to drop a frame) and updates its
+  // internal statistics.
+  //
+  // Input:
+  //          - frameSizeBytes    : The size of the latest frame
+  //                                returned from the encoder.
+  //          - deltaFrame        : True if the encoder returned
+  //                                a key frame.
+  virtual void Fill(size_t frameSizeBytes, bool deltaFrame);
+
+  virtual void Leak(uint32_t inputFrameRate);
+
+  // Sets the target bit rate and the frame rate produced by
+  // the camera.
+  //
+  // Input:
+  //          - bitRate       : The target bit rate
+  virtual void SetRates(float bitRate, float incoming_frame_rate);
+
+ private:
+  void UpdateRatio();
+  void CapAccumulator();
+
+  rtc::ExpFilter key_frame_ratio_;
+  rtc::ExpFilter delta_frame_size_avg_kbits_;
+
+  // Key frames and large delta frames are not immediately accumulated in the
+  // bucket since they can immediately overflow the bucket leading to large
+  // drops on the following packets that may be much smaller. Instead these
+  // large frames are accumulated over several frames when the bucket leaks.
+
+  // |large_frame_accumulation_spread_| represents the number of frames over
+  // which a large frame is accumulated.
+  float large_frame_accumulation_spread_;
+  // |large_frame_accumulation_count_| represents the number of frames left
+  // to finish accumulating a large frame.
+  int large_frame_accumulation_count_;
+  // |large_frame_accumulation_chunk_size_| represents the size of a single
+  // chunk for large frame accumulation.
+  float large_frame_accumulation_chunk_size_;
+
+  float accumulator_;
+  float accumulator_max_;
+  float target_bitrate_;
+  bool drop_next_;
+  rtc::ExpFilter drop_ratio_;
+  int drop_count_;
+  float incoming_frame_rate_;
+  bool was_below_max_;
+  bool enabled_;
+  const float max_drop_duration_secs_;
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_MODULES_VIDEO_CODING_UTILITY_FRAME_DROPPER_H_