1 /* 2 * Copyright (c) 2014 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 WEBRTC_MODULES_REMOTE_BITRATE_ESTIMATOR_AIMD_RATE_CONTROL_H_ 12 #define WEBRTC_MODULES_REMOTE_BITRATE_ESTIMATOR_AIMD_RATE_CONTROL_H_ 13 14 #include "webrtc/base/constructormagic.h" 15 #include "webrtc/modules/remote_bitrate_estimator/include/bwe_defines.h" 16 17 namespace webrtc { 18 19 // A rate control implementation based on additive increases of 20 // bitrate when no over-use is detected and multiplicative decreases when 21 // over-uses are detected. When we think the available bandwidth has changes or 22 // is unknown, we will switch to a "slow-start mode" where we increase 23 // multiplicatively. 24 class AimdRateControl { 25 public: 26 AimdRateControl(); ~AimdRateControl()27 virtual ~AimdRateControl() {} 28 29 // Returns true if there is a valid estimate of the incoming bitrate, false 30 // otherwise. 31 bool ValidEstimate() const; 32 void SetMinBitrate(int min_bitrate_bps); 33 int64_t GetFeedbackInterval() const; 34 // Returns true if the bitrate estimate hasn't been changed for more than 35 // an RTT, or if the incoming_bitrate is more than 5% above the current 36 // estimate. Should be used to decide if we should reduce the rate further 37 // when over-using. 38 bool TimeToReduceFurther(int64_t time_now, 39 uint32_t incoming_bitrate_bps) const; 40 uint32_t LatestEstimate() const; 41 uint32_t UpdateBandwidthEstimate(int64_t now_ms); 42 void SetRtt(int64_t rtt); 43 void Update(const RateControlInput* input, int64_t now_ms); 44 void SetEstimate(int bitrate_bps, int64_t now_ms); 45 46 private: 47 // Update the target bitrate according based on, among other things, 48 // the current rate control state, the current target bitrate and the incoming 49 // bitrate. When in the "increase" state the bitrate will be increased either 50 // additively or multiplicatively depending on the rate control region. When 51 // in the "decrease" state the bitrate will be decreased to slightly below the 52 // incoming bitrate. When in the "hold" state the bitrate will be kept 53 // constant to allow built up queues to drain. 54 uint32_t ChangeBitrate(uint32_t current_bit_rate, 55 uint32_t incoming_bit_rate, 56 int64_t now_ms); 57 uint32_t MultiplicativeRateIncrease(int64_t now_ms, int64_t last_ms, 58 uint32_t current_bitrate_bps) const; 59 uint32_t AdditiveRateIncrease(int64_t now_ms, int64_t last_ms, 60 int64_t response_time_ms) const; 61 void UpdateChangePeriod(int64_t now_ms); 62 void UpdateMaxBitRateEstimate(float incoming_bit_rate_kbps); 63 void ChangeState(const RateControlInput& input, int64_t now_ms); 64 void ChangeState(RateControlState new_state); 65 void ChangeRegion(RateControlRegion region); 66 67 uint32_t min_configured_bitrate_bps_; 68 uint32_t max_configured_bitrate_bps_; 69 uint32_t current_bitrate_bps_; 70 uint32_t max_hold_rate_bps_; 71 float avg_max_bitrate_kbps_; 72 float var_max_bitrate_kbps_; 73 RateControlState rate_control_state_; 74 RateControlRegion rate_control_region_; 75 int64_t time_last_bitrate_change_; 76 RateControlInput current_input_; 77 bool updated_; 78 int64_t time_first_incoming_estimate_; 79 bool bitrate_is_initialized_; 80 float beta_; 81 int64_t rtt_; 82 int64_t time_of_last_log_; 83 bool in_experiment_; 84 }; 85 } // namespace webrtc 86 87 #endif // WEBRTC_MODULES_REMOTE_BITRATE_ESTIMATOR_AIMD_RATE_CONTROL_H_ 88