ed2207abee
When a bandwidth decrease to the estimated throughput would lead to the "critical low" region we allow dropping to the link capacity estimate instead (if it is higher). Also moved BweInitialBackOffInterval config to the same field trial string. Bug: webrtc:10462 Change-Id: I4d6ee020a9ab8cede035b64253e3b3b1e2fb92b1 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/129920 Reviewed-by: Sebastian Jansson <srte@webrtc.org> Commit-Queue: Christoffer Rodbro <crodbro@webrtc.org> Cr-Commit-Position: refs/heads/master@{#27325}
106 lines
4.6 KiB
C++
106 lines
4.6 KiB
C++
/*
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* Copyright (c) 2014 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 MODULES_REMOTE_BITRATE_ESTIMATOR_AIMD_RATE_CONTROL_H_
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#define MODULES_REMOTE_BITRATE_ESTIMATOR_AIMD_RATE_CONTROL_H_
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#include <stdint.h>
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#include "absl/types/optional.h"
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#include "api/units/data_rate.h"
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#include "api/units/timestamp.h"
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#include "modules/congestion_controller/goog_cc/link_capacity_estimator.h"
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#include "modules/remote_bitrate_estimator/include/bwe_defines.h"
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#include "rtc_base/experiments/field_trial_parser.h"
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namespace webrtc {
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// A rate control implementation based on additive increases of
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// bitrate when no over-use is detected and multiplicative decreases when
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// over-uses are detected. When we think the available bandwidth has changes or
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// is unknown, we will switch to a "slow-start mode" where we increase
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// multiplicatively.
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class AimdRateControl {
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public:
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AimdRateControl();
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~AimdRateControl();
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// Returns true if the target bitrate has been initialized. This happens
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// either if it has been explicitly set via SetStartBitrate/SetEstimate, or if
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// we have measured a throughput.
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bool ValidEstimate() const;
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void SetStartBitrate(DataRate start_bitrate);
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void SetMinBitrate(DataRate min_bitrate);
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TimeDelta GetFeedbackInterval() const;
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// Returns true if the bitrate estimate hasn't been changed for more than
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// an RTT, or if the estimated_throughput is less than half of the current
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// estimate. Should be used to decide if we should reduce the rate further
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// when over-using.
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bool TimeToReduceFurther(Timestamp at_time,
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DataRate estimated_throughput) const;
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// As above. To be used if overusing before we have measured a throughput.
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bool InitialTimeToReduceFurther(Timestamp at_time) const;
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DataRate LatestEstimate() const;
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void SetRtt(TimeDelta rtt);
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DataRate Update(const RateControlInput* input, Timestamp at_time);
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void SetEstimate(DataRate bitrate, Timestamp at_time);
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// Returns the increase rate when used bandwidth is near the link capacity.
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double GetNearMaxIncreaseRateBpsPerSecond() const;
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// Returns the expected time between overuse signals (assuming steady state).
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TimeDelta GetExpectedBandwidthPeriod() const;
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private:
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friend class GoogCcStatePrinter;
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// Update the target bitrate based on, among other things, the current rate
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// control state, the current target bitrate and the estimated throughput.
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// When in the "increase" state the bitrate will be increased either
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// additively or multiplicatively depending on the rate control region. When
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// in the "decrease" state the bitrate will be decreased to slightly below the
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// current throughput. When in the "hold" state the bitrate will be kept
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// constant to allow built up queues to drain.
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DataRate ChangeBitrate(DataRate current_bitrate,
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const RateControlInput& input,
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Timestamp at_time);
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// Clamps new_bitrate to within the configured min bitrate and a linear
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// function of the throughput, so that the new bitrate can't grow too
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// large compared to the bitrate actually being received by the other end.
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DataRate ClampBitrate(DataRate new_bitrate,
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DataRate estimated_throughput) const;
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DataRate MultiplicativeRateIncrease(Timestamp at_time,
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Timestamp last_ms,
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DataRate current_bitrate) const;
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DataRate AdditiveRateIncrease(Timestamp at_time, Timestamp last_time) const;
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void UpdateChangePeriod(Timestamp at_time);
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void ChangeState(const RateControlInput& input, Timestamp at_time);
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DataRate min_configured_bitrate_;
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DataRate max_configured_bitrate_;
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DataRate current_bitrate_;
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DataRate latest_estimated_throughput_;
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LinkCapacityEstimator link_capacity_;
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RateControlState rate_control_state_;
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Timestamp time_last_bitrate_change_;
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Timestamp time_last_bitrate_decrease_;
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Timestamp time_first_throughput_estimate_;
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bool bitrate_is_initialized_;
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double beta_;
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TimeDelta rtt_;
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const bool in_experiment_;
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const bool smoothing_experiment_;
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absl::optional<DataRate> last_decrease_;
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FieldTrialOptional<TimeDelta> initial_backoff_interval_;
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FieldTrialParameter<DataRate> low_throughput_threshold_;
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};
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} // namespace webrtc
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#endif // MODULES_REMOTE_BITRATE_ESTIMATOR_AIMD_RATE_CONTROL_H_
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