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* Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
#include "webrtc/modules/remote_bitrate_estimator/include/bwe_defines.h"
#include "webrtc/rtc_base/constructormagic.h"
namespace webrtc {
// A rate control implementation based on additive increases of
// bitrate when no over-use is detected and multiplicative decreases when
// over-uses are detected. When we think the available bandwidth has changes or
// is unknown, we will switch to a "slow-start mode" where we increase
// multiplicatively.
class AimdRateControl {
// Returns true if there is a valid estimate of the incoming bitrate, false
// otherwise.
bool ValidEstimate() const;
void SetStartBitrate(int start_bitrate_bps);
void SetMinBitrate(int min_bitrate_bps);
int64_t GetFeedbackInterval() const;
// Returns true if the bitrate estimate hasn't been changed for more than
// an RTT, or if the incoming_bitrate is less than half of the current
// estimate. Should be used to decide if we should reduce the rate further
// when over-using.
bool TimeToReduceFurther(int64_t time_now,
uint32_t incoming_bitrate_bps) const;
uint32_t LatestEstimate() const;
void SetRtt(int64_t rtt);
uint32_t Update(const RateControlInput* input, int64_t now_ms);
void SetEstimate(int bitrate_bps, int64_t now_ms);
// Returns the increase rate when used bandwidth is near the link capacity.
int GetNearMaxIncreaseRateBps() const;
// Returns the expected time between overuse signals (assuming steady state).
int GetExpectedBandwidthPeriodMs() const;
// Update the target bitrate according based on, among other things,
// the current rate control state, the current target bitrate and the incoming
// bitrate. When in the "increase" state the bitrate will be increased either
// additively or multiplicatively depending on the rate control region. When
// in the "decrease" state the bitrate will be decreased to slightly below the
// incoming bitrate. When in the "hold" state the bitrate will be kept
// constant to allow built up queues to drain.
uint32_t ChangeBitrate(uint32_t current_bitrate,
const RateControlInput& input,
int64_t now_ms);
// Clamps new_bitrate_bps to within the configured min bitrate and a linear
// function of the incoming bitrate, so that the new bitrate can't grow too
// large compared to the bitrate actually being received by the other end.
uint32_t ClampBitrate(uint32_t new_bitrate_bps,
uint32_t incoming_bitrate_bps) const;
uint32_t MultiplicativeRateIncrease(int64_t now_ms, int64_t last_ms,
uint32_t current_bitrate_bps) const;
uint32_t AdditiveRateIncrease(int64_t now_ms, int64_t last_ms) const;
void UpdateChangePeriod(int64_t now_ms);
void UpdateMaxBitRateEstimate(float incoming_bit_rate_kbps);
void ChangeState(const RateControlInput& input, int64_t now_ms);
void ChangeRegion(RateControlRegion region);
uint32_t min_configured_bitrate_bps_;
uint32_t max_configured_bitrate_bps_;
uint32_t current_bitrate_bps_;
float avg_max_bitrate_kbps_;
float var_max_bitrate_kbps_;
RateControlState rate_control_state_;
RateControlRegion rate_control_region_;
int64_t time_last_bitrate_change_;
int64_t time_first_incoming_estimate_;
bool bitrate_is_initialized_;
float beta_;
int64_t rtt_;
bool in_experiment_;
rtc::Optional<int> last_decrease_;
} // namespace webrtc