61 lines
2.1 KiB
C
61 lines
2.1 KiB
C
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/*
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* Copyright (c) 2019 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 COMMON_VIDEO_FRAME_RATE_ESTIMATOR_H_
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#define COMMON_VIDEO_FRAME_RATE_ESTIMATOR_H_
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#include <deque>
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#include "absl/types/optional.h"
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#include "api/units/time_delta.h"
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#include "api/units/timestamp.h"
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namespace webrtc {
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// Class used to estimate a frame-rate using inter-frame intervals.
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// Some notes on usage:
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// This class is intended to accurately estimate the frame rate during a
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// continuous stream. Unlike a traditional rate estimator that looks at number
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// of data points within a time window, if the input stops this implementation
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// will not smoothly fall down towards 0. This is done so that the estimated
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// fps is not affected by edge conditions like if we sample just before or just
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// after the next frame.
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// To avoid problems if a stream is stopped and restarted (where estimated fps
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// could look too low), users of this class should explicitly call Reset() on
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// restart.
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// Also note that this class is not thread safe, it's up to the user to guard
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// against concurrent access.
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class FrameRateEstimator {
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public:
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explicit FrameRateEstimator(TimeDelta averaging_window);
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// Insert a frame, potentially culling old frames that falls outside the
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// averaging window.
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void OnFrame(Timestamp time);
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// Get the current average FPS, based on the frames currently in the window.
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absl::optional<double> GetAverageFps() const;
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// Move the window so it ends at |now|, and return the new fps estimate.
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absl::optional<double> GetAverageFps(Timestamp now);
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// Completely clear the averaging window.
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void Reset();
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private:
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void CullOld(Timestamp now);
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const TimeDelta averaging_window_;
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std::deque<Timestamp> frame_times_;
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};
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} // namespace webrtc
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#endif // COMMON_VIDEO_FRAME_RATE_ESTIMATOR_H_
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