84cd8e39cf
BUG=1466 Review URL: https://webrtc-codereview.appspot.com/1170004 git-svn-id: http://webrtc.googlecode.com/svn/trunk@3629 4adac7df-926f-26a2-2b94-8c16560cd09d
97 lines
3.4 KiB
C++
97 lines
3.4 KiB
C++
/*
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* Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#ifndef WEBRTC_MODULES_VIDEO_CODING_UTILITY_INCLUDE_FRAME_DROPPER_H_
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#define WEBRTC_MODULES_VIDEO_CODING_UTILITY_INCLUDE_FRAME_DROPPER_H_
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#include "webrtc/modules/video_coding/utility/include/exp_filter.h"
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#include "webrtc/typedefs.h"
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namespace webrtc
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{
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// The Frame Dropper implements a variant of the leaky bucket algorithm
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// for keeping track of when to drop frames to avoid bit rate
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// over use when the encoder can't keep its bit rate.
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class FrameDropper
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{
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public:
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FrameDropper();
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explicit FrameDropper(float max_time_drops);
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virtual ~FrameDropper() {}
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// Resets the FrameDropper to its initial state.
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// This means that the frameRateWeight is set to its
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// default value as well.
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virtual void Reset();
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virtual void Enable(bool enable);
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// Answers the question if it's time to drop a frame
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// if we want to reach a given frame rate. Must be
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// called for every frame.
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//
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// Return value : True if we should drop the current frame
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virtual bool DropFrame();
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// Updates the FrameDropper with the size of the latest encoded
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// frame. The FrameDropper calculates a new drop ratio (can be
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// seen as the probability to drop a frame) and updates its
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// internal statistics.
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//
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// Input:
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// - frameSizeBytes : The size of the latest frame
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// returned from the encoder.
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// - deltaFrame : True if the encoder returned
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// a key frame.
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virtual void Fill(WebRtc_UWord32 frameSizeBytes, bool deltaFrame);
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virtual void Leak(WebRtc_UWord32 inputFrameRate);
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void UpdateNack(WebRtc_UWord32 nackBytes);
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// Sets the target bit rate and the frame rate produced by
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// the camera.
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//
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// Input:
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// - bitRate : The target bit rate
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virtual void SetRates(float bitRate, float incoming_frame_rate);
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// Return value : The current average frame rate produced
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// if the DropFrame() function is used as
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// instruction of when to drop frames.
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virtual float ActualFrameRate(WebRtc_UWord32 inputFrameRate) const;
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private:
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void FillBucket(float inKbits, float outKbits);
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void UpdateRatio();
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void CapAccumulator();
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VCMExpFilter _keyFrameSizeAvgKbits;
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VCMExpFilter _keyFrameRatio;
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float _keyFrameSpreadFrames;
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WebRtc_Word32 _keyFrameCount;
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float _accumulator;
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float _accumulatorMax;
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float _targetBitRate;
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bool _dropNext;
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VCMExpFilter _dropRatio;
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WebRtc_Word32 _dropCount;
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float _windowSize;
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float _incoming_frame_rate;
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bool _wasBelowMax;
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bool _enabled;
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bool _fastMode;
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float _cap_buffer_size;
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float _max_time_drops;
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}; // end of VCMFrameDropper class
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} // namespace webrtc
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#endif // WEBRTC_MODULES_VIDEO_CODING_UTILITY_INCLUDE_FRAME_DROPPER_H_
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