Erik Språng | c592257 | 2024-07-04 15:28:52 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (c) 2024 The WebRTC project authors. All Rights Reserved. |
| 3 | * |
| 4 | * Use of this source code is governed by a BSD-style license |
| 5 | * that can be found in the LICENSE file in the root of the source |
| 6 | * tree. An additional intellectual property rights grant can be found |
| 7 | * in the file PATENTS. All contributing project authors may |
| 8 | * be found in the AUTHORS file in the root of the source tree. |
| 9 | */ |
| 10 | |
| 11 | #ifndef VIDEO_RATE_UTILIZATION_TRACKER_H_ |
| 12 | #define VIDEO_RATE_UTILIZATION_TRACKER_H_ |
| 13 | |
| 14 | #include <deque> |
Florent Castelli | 8037fc6 | 2024-08-29 13:00:40 | [diff] [blame] | 15 | #include <optional> |
Erik Språng | c592257 | 2024-07-04 15:28:52 | [diff] [blame] | 16 | |
Erik Språng | c592257 | 2024-07-04 15:28:52 | [diff] [blame] | 17 | #include "api/units/data_rate.h" |
| 18 | #include "api/units/data_size.h" |
| 19 | #include "api/units/time_delta.h" |
| 20 | #include "api/units/timestamp.h" |
| 21 | |
| 22 | namespace webrtc { |
| 23 | |
| 24 | // Helper class that tracks the rate of utilization over a sliding window. |
| 25 | // tl;dr: if an encoder has a target rate of 1000kbps but in practice |
| 26 | // produces 500kbps it would have a utilization factor of 0.5. |
| 27 | // The tracker looks only at discrete events, and keeps only a fixed amount |
| 28 | // of data points (e.g. encoded frames) or points newer than a given time |
| 29 | // limit, whichever is lower. |
| 30 | |
| 31 | // More precisely This class measures the allocated cumulative byte budget (as |
| 32 | // specified by one or more rate updates) and the actual cumulative number of |
| 33 | // bytes produced over a sliding window. A utilization factor (produced bytes / |
| 34 | // budgeted bytes) is calculated seen from the first data point timestamp until |
| 35 | // the last data point timestamp plus the amount time needed to send that last |
| 36 | // data point given no further updates to the rate. The implication of this is a |
| 37 | // smoother value, and e.g. setting a rate and adding a data point, then |
| 38 | // immediately querying the utilization reports 1.0 utilization instead of some |
| 39 | // undefined state. |
| 40 | |
| 41 | class RateUtilizationTracker { |
| 42 | public: |
| 43 | RateUtilizationTracker(size_t max_num_encoded_data_points, |
| 44 | TimeDelta max_duration); |
| 45 | |
| 46 | // The timestamps used should never decrease relative the last one. |
| 47 | void OnDataRateChanged(DataRate rate, Timestamp time); |
| 48 | void OnDataProduced(DataSize size, Timestamp time); |
Florent Castelli | 8037fc6 | 2024-08-29 13:00:40 | [diff] [blame] | 49 | std::optional<double> GetRateUtilizationFactor(Timestamp time) const; |
Erik Språng | c592257 | 2024-07-04 15:28:52 | [diff] [blame] | 50 | |
| 51 | private: |
| 52 | struct RateUsageUpdate { |
| 53 | Timestamp time; |
| 54 | DataRate target_rate; |
| 55 | DataSize produced_data; |
| 56 | }; |
| 57 | |
| 58 | void CullOldData(Timestamp time); |
| 59 | |
| 60 | const size_t max_data_points_; |
| 61 | const TimeDelta max_duration_; |
| 62 | DataRate current_rate_; |
| 63 | std::deque<RateUsageUpdate> data_points_; |
| 64 | }; |
| 65 | |
| 66 | } // namespace webrtc |
| 67 | |
| 68 | #endif // VIDEO_RATE_UTILIZATION_TRACKER_H_ |