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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.
*/
#ifndef WEBRTC_MODULES_REMOTE_BITRATE_ESTIMATOR_AIMD_RATE_CONTROL_H_
#define WEBRTC_MODULES_REMOTE_BITRATE_ESTIMATOR_AIMD_RATE_CONTROL_H_
#include "webrtc/modules/remote_bitrate_estimator/include/bwe_defines.h"
#include "webrtc/modules/remote_bitrate_estimator/remote_rate_control.h"
namespace webrtc {
// A RemoteRateControl 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 : public RemoteRateControl {
public:
explicit AimdRateControl(uint32_t min_bitrate_bps);
virtual ~AimdRateControl() {}
// Implements RemoteRateControl.
virtual bool ValidEstimate() const OVERRIDE;
virtual RateControlType GetControlType() const OVERRIDE;
virtual uint32_t GetMinBitrate() const OVERRIDE;
virtual int64_t GetFeedbackInterval() const OVERRIDE;
// Returns true if the bitrate estimate hasn't been changed for more than
// an RTT, or if the incoming_bitrate is more than 5% above the current
// estimate. Should be used to decide if we should reduce the rate further
// when over-using.
virtual bool TimeToReduceFurther(
int64_t time_now, uint32_t incoming_bitrate_bps) const OVERRIDE;
virtual uint32_t LatestEstimate() const OVERRIDE;
virtual uint32_t UpdateBandwidthEstimate(int64_t now_ms) OVERRIDE;
virtual void SetRtt(uint32_t rtt) OVERRIDE;
virtual RateControlRegion Update(const RateControlInput* input,
int64_t now_ms) OVERRIDE;
virtual void SetEstimate(int bitrate_bps, int64_t now_ms) OVERRIDE;
private:
// 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_bit_rate,
uint32_t incoming_bit_rate,
int64_t now_ms);
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,
uint32_t response_time_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 ChangeState(RateControlState new_state);
void ChangeRegion(RateControlRegion region);
uint32_t min_configured_bitrate_bps_;
uint32_t max_configured_bitrate_bps_;
uint32_t current_bitrate_bps_;
uint32_t max_hold_rate_bps_;
float avg_max_bitrate_kbps_;
float var_max_bitrate_kbps_;
RateControlState rate_control_state_;
RateControlState came_from_state_;
RateControlRegion rate_control_region_;
int64_t time_last_bitrate_change_;
RateControlInput current_input_;
bool updated_;
int64_t time_first_incoming_estimate_;
bool bitrate_is_initialized_;
float beta_;
uint32_t rtt_;
int64_t time_of_last_log_;
DISALLOW_IMPLICIT_CONSTRUCTORS(AimdRateControl);
};
} // namespace webrtc
#endif // WEBRTC_MODULES_REMOTE_BITRATE_ESTIMATOR_AIMD_RATE_CONTROL_H_
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