| /* |
| * Copyright (c) 2016 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/congestion_controller/delay_based_bwe.h" |
| |
| #include <algorithm> |
| #include <cmath> |
| |
| #include "webrtc/base/checks.h" |
| #include "webrtc/base/constructormagic.h" |
| #include "webrtc/base/logging.h" |
| #include "webrtc/base/thread_annotations.h" |
| #include "webrtc/modules/congestion_controller/include/congestion_controller.h" |
| #include "webrtc/modules/pacing/paced_sender.h" |
| #include "webrtc/modules/remote_bitrate_estimator/include/remote_bitrate_estimator.h" |
| #include "webrtc/system_wrappers/include/field_trial.h" |
| #include "webrtc/system_wrappers/include/metrics.h" |
| #include "webrtc/typedefs.h" |
| |
| namespace { |
| constexpr int kTimestampGroupLengthMs = 5; |
| constexpr int kAbsSendTimeFraction = 18; |
| constexpr int kAbsSendTimeInterArrivalUpshift = 8; |
| constexpr int kInterArrivalShift = |
| kAbsSendTimeFraction + kAbsSendTimeInterArrivalUpshift; |
| constexpr double kTimestampToMs = |
| 1000.0 / static_cast<double>(1 << kInterArrivalShift); |
| // This ssrc is used to fulfill the current API but will be removed |
| // after the API has been changed. |
| constexpr uint32_t kFixedSsrc = 0; |
| constexpr int kInitialRateWindowMs = 500; |
| constexpr int kRateWindowMs = 150; |
| |
| const char kBitrateEstimateExperiment[] = "WebRTC-ImprovedBitrateEstimate"; |
| |
| bool BitrateEstimateExperimentIsEnabled() { |
| return webrtc::field_trial::FindFullName(kBitrateEstimateExperiment) == |
| "Enabled"; |
| } |
| } // namespace |
| |
| namespace webrtc { |
| DelayBasedBwe::BitrateEstimator::BitrateEstimator() |
| : sum_(0), |
| current_win_ms_(0), |
| prev_time_ms_(-1), |
| bitrate_estimate_(-1.0f), |
| bitrate_estimate_var_(50.0f), |
| old_estimator_(kBitrateWindowMs, 8000), |
| in_experiment_(BitrateEstimateExperimentIsEnabled()) {} |
| |
| void DelayBasedBwe::BitrateEstimator::Update(int64_t now_ms, int bytes) { |
| if (!in_experiment_) { |
| old_estimator_.Update(bytes, now_ms); |
| rtc::Optional<uint32_t> rate = old_estimator_.Rate(now_ms); |
| bitrate_estimate_ = -1.0f; |
| if (rate) |
| bitrate_estimate_ = *rate / 1000.0f; |
| return; |
| } |
| int rate_window_ms = kRateWindowMs; |
| // We use a larger window at the beginning to get a more stable sample that |
| // we can use to initialize the estimate. |
| if (bitrate_estimate_ < 0.f) |
| rate_window_ms = kInitialRateWindowMs; |
| float bitrate_sample = UpdateWindow(now_ms, bytes, rate_window_ms); |
| if (bitrate_sample < 0.0f) |
| return; |
| if (bitrate_estimate_ < 0.0f) { |
| // This is the very first sample we get. Use it to initialize the estimate. |
| bitrate_estimate_ = bitrate_sample; |
| return; |
| } |
| // Define the sample uncertainty as a function of how far away it is from the |
| // current estimate. |
| float sample_uncertainty = |
| 10.0f * std::abs(bitrate_estimate_ - bitrate_sample) / bitrate_estimate_; |
| float sample_var = sample_uncertainty * sample_uncertainty; |
| // Update a bayesian estimate of the rate, weighting it lower if the sample |
| // uncertainty is large. |
| // The bitrate estimate uncertainty is increased with each update to model |
| // that the bitrate changes over time. |
| float pred_bitrate_estimate_var = bitrate_estimate_var_ + 5.f; |
| bitrate_estimate_ = (sample_var * bitrate_estimate_ + |
| pred_bitrate_estimate_var * bitrate_sample) / |
| (sample_var + pred_bitrate_estimate_var); |
| bitrate_estimate_var_ = sample_var * pred_bitrate_estimate_var / |
| (sample_var + pred_bitrate_estimate_var); |
| } |
| |
| float DelayBasedBwe::BitrateEstimator::UpdateWindow(int64_t now_ms, |
| int bytes, |
| int rate_window_ms) { |
| // Reset if time moves backwards. |
| if (now_ms < prev_time_ms_) { |
| prev_time_ms_ = -1; |
| sum_ = 0; |
| current_win_ms_ = 0; |
| } |
| if (prev_time_ms_ >= 0) { |
| current_win_ms_ += now_ms - prev_time_ms_; |
| // Reset if nothing has been received for more than a full window. |
| if (now_ms - prev_time_ms_ > rate_window_ms) { |
| sum_ = 0; |
| current_win_ms_ %= rate_window_ms; |
| } |
| } |
| prev_time_ms_ = now_ms; |
| float bitrate_sample = -1.0f; |
| if (current_win_ms_ >= rate_window_ms) { |
| bitrate_sample = 8.0f * sum_ / static_cast<float>(rate_window_ms); |
| current_win_ms_ -= rate_window_ms; |
| sum_ = 0; |
| } |
| sum_ += bytes; |
| return bitrate_sample; |
| } |
| |
| rtc::Optional<uint32_t> DelayBasedBwe::BitrateEstimator::bitrate_bps() const { |
| if (bitrate_estimate_ < 0.f) |
| return rtc::Optional<uint32_t>(); |
| return rtc::Optional<uint32_t>(bitrate_estimate_ * 1000); |
| } |
| |
| DelayBasedBwe::DelayBasedBwe(Clock* clock) |
| : clock_(clock), |
| inter_arrival_(), |
| estimator_(), |
| detector_(OverUseDetectorOptions()), |
| receiver_incoming_bitrate_(), |
| last_update_ms_(-1), |
| last_seen_packet_ms_(-1), |
| uma_recorded_(false) { |
| network_thread_.DetachFromThread(); |
| } |
| |
| DelayBasedBwe::Result DelayBasedBwe::IncomingPacketFeedbackVector( |
| const std::vector<PacketInfo>& packet_feedback_vector) { |
| RTC_DCHECK(network_thread_.CalledOnValidThread()); |
| if (!uma_recorded_) { |
| RTC_HISTOGRAM_ENUMERATION(kBweTypeHistogram, |
| BweNames::kSendSideTransportSeqNum, |
| BweNames::kBweNamesMax); |
| uma_recorded_ = true; |
| } |
| Result aggregated_result; |
| for (const auto& packet_info : packet_feedback_vector) { |
| Result result = IncomingPacketInfo(packet_info); |
| if (result.updated) |
| aggregated_result = result; |
| } |
| return aggregated_result; |
| } |
| |
| DelayBasedBwe::Result DelayBasedBwe::IncomingPacketInfo( |
| const PacketInfo& info) { |
| int64_t now_ms = clock_->TimeInMilliseconds(); |
| |
| receiver_incoming_bitrate_.Update(info.arrival_time_ms, info.payload_size); |
| Result result; |
| // Reset if the stream has timed out. |
| if (last_seen_packet_ms_ == -1 || |
| now_ms - last_seen_packet_ms_ > kStreamTimeOutMs) { |
| inter_arrival_.reset( |
| new InterArrival((kTimestampGroupLengthMs << kInterArrivalShift) / 1000, |
| kTimestampToMs, true)); |
| estimator_.reset(new OveruseEstimator(OverUseDetectorOptions())); |
| } |
| last_seen_packet_ms_ = now_ms; |
| |
| uint32_t send_time_24bits = |
| static_cast<uint32_t>( |
| ((static_cast<uint64_t>(info.send_time_ms) << kAbsSendTimeFraction) + |
| 500) / |
| 1000) & |
| 0x00FFFFFF; |
| // Shift up send time to use the full 32 bits that inter_arrival works with, |
| // so wrapping works properly. |
| uint32_t timestamp = send_time_24bits << kAbsSendTimeInterArrivalUpshift; |
| |
| uint32_t ts_delta = 0; |
| int64_t t_delta = 0; |
| int size_delta = 0; |
| if (inter_arrival_->ComputeDeltas(timestamp, info.arrival_time_ms, now_ms, |
| info.payload_size, &ts_delta, &t_delta, |
| &size_delta)) { |
| double ts_delta_ms = (1000.0 * ts_delta) / (1 << kInterArrivalShift); |
| estimator_->Update(t_delta, ts_delta_ms, size_delta, detector_.State(), |
| info.arrival_time_ms); |
| detector_.Detect(estimator_->offset(), ts_delta_ms, |
| estimator_->num_of_deltas(), info.arrival_time_ms); |
| } |
| |
| int probing_bps = 0; |
| if (info.probe_cluster_id != PacketInfo::kNotAProbe) { |
| probing_bps = probe_bitrate_estimator_.HandleProbeAndEstimateBitrate(info); |
| } |
| rtc::Optional<uint32_t> acked_bitrate_bps = |
| receiver_incoming_bitrate_.bitrate_bps(); |
| // Currently overusing the bandwidth. |
| if (detector_.State() == kBwOverusing) { |
| if (acked_bitrate_bps && |
| rate_control_.TimeToReduceFurther(now_ms, *acked_bitrate_bps)) { |
| result.updated = |
| UpdateEstimate(info.arrival_time_ms, now_ms, acked_bitrate_bps, |
| &result.target_bitrate_bps); |
| } |
| } else if (probing_bps > 0) { |
| // No overuse, but probing measured a bitrate. |
| rate_control_.SetEstimate(probing_bps, info.arrival_time_ms); |
| result.probe = true; |
| result.updated = |
| UpdateEstimate(info.arrival_time_ms, now_ms, acked_bitrate_bps, |
| &result.target_bitrate_bps); |
| } |
| if (!result.updated && |
| (last_update_ms_ == -1 || |
| now_ms - last_update_ms_ > rate_control_.GetFeedbackInterval())) { |
| result.updated = |
| UpdateEstimate(info.arrival_time_ms, now_ms, acked_bitrate_bps, |
| &result.target_bitrate_bps); |
| } |
| if (result.updated) |
| last_update_ms_ = now_ms; |
| |
| return result; |
| } |
| |
| bool DelayBasedBwe::UpdateEstimate(int64_t arrival_time_ms, |
| int64_t now_ms, |
| rtc::Optional<uint32_t> acked_bitrate_bps, |
| uint32_t* target_bitrate_bps) { |
| const RateControlInput input(detector_.State(), acked_bitrate_bps, |
| estimator_->var_noise()); |
| rate_control_.Update(&input, now_ms); |
| *target_bitrate_bps = rate_control_.UpdateBandwidthEstimate(now_ms); |
| return rate_control_.ValidEstimate(); |
| } |
| |
| void DelayBasedBwe::OnRttUpdate(int64_t avg_rtt_ms, int64_t max_rtt_ms) { |
| rate_control_.SetRtt(avg_rtt_ms); |
| } |
| |
| bool DelayBasedBwe::LatestEstimate(std::vector<uint32_t>* ssrcs, |
| uint32_t* bitrate_bps) const { |
| // Currently accessed from both the process thread (see |
| // ModuleRtpRtcpImpl::Process()) and the configuration thread (see |
| // Call::GetStats()). Should in the future only be accessed from a single |
| // thread. |
| RTC_DCHECK(ssrcs); |
| RTC_DCHECK(bitrate_bps); |
| if (!rate_control_.ValidEstimate()) |
| return false; |
| |
| *ssrcs = {kFixedSsrc}; |
| *bitrate_bps = rate_control_.LatestEstimate(); |
| return true; |
| } |
| |
| void DelayBasedBwe::SetMinBitrate(int min_bitrate_bps) { |
| // Called from both the configuration thread and the network thread. Shouldn't |
| // be called from the network thread in the future. |
| rate_control_.SetMinBitrate(min_bitrate_bps); |
| } |
| } // namespace webrtc |