68 lines
2.4 KiB
C++
68 lines
2.4 KiB
C++
/*
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* Copyright (c) 2024 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 VIDEO_RATE_UTILIZATION_TRACKER_H_
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#define VIDEO_RATE_UTILIZATION_TRACKER_H_
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#include <deque>
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#include <optional>
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#include "api/units/data_rate.h"
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#include "api/units/data_size.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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// Helper class that tracks the rate of utilization over a sliding window.
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// tl;dr: if an encoder has a target rate of 1000kbps but in practice
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// produces 500kbps it would have a utilization factor of 0.5.
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// The tracker looks only at discrete events, and keeps only a fixed amount
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// of data points (e.g. encoded frames) or points newer than a given time
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// limit, whichever is lower.
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// More precisely This class measures the allocated cumulative byte budget (as
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// specified by one or more rate updates) and the actual cumulative number of
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// bytes produced over a sliding window. A utilization factor (produced bytes /
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// budgeted bytes) is calculated seen from the first data point timestamp until
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// the last data point timestamp plus the amount time needed to send that last
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// data point given no further updates to the rate. The implication of this is a
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// smoother value, and e.g. setting a rate and adding a data point, then
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// immediately querying the utilization reports 1.0 utilization instead of some
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// undefined state.
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class RateUtilizationTracker {
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public:
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RateUtilizationTracker(size_t max_num_encoded_data_points,
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TimeDelta max_duration);
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// The timestamps used should never decrease relative the last one.
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void OnDataRateChanged(DataRate rate, Timestamp time);
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void OnDataProduced(DataSize size, Timestamp time);
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std::optional<double> GetRateUtilizationFactor(Timestamp time) const;
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private:
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struct RateUsageUpdate {
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Timestamp time;
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DataRate target_rate;
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DataSize produced_data;
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};
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void CullOldData(Timestamp time);
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const size_t max_data_points_;
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const TimeDelta max_duration_;
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DataRate current_rate_;
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std::deque<RateUsageUpdate> data_points_;
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};
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} // namespace webrtc
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#endif // VIDEO_RATE_UTILIZATION_TRACKER_H_
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