blob: a1672cbb3f73852b64ae5618e3c9d1e2bbc66109 [file] [log] [blame]
/*
* Copyright (c) 2012 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 "modules/bitrate_controller/send_side_bandwidth_estimation.h"
#include <algorithm>
#include <cstdio>
#include <limits>
#include <string>
#include "absl/memory/memory.h"
#include "logging/rtc_event_log/events/rtc_event.h"
#include "logging/rtc_event_log/events/rtc_event_bwe_update_loss_based.h"
#include "logging/rtc_event_log/rtc_event_log.h"
#include "modules/remote_bitrate_estimator/include/bwe_defines.h"
#include "rtc_base/checks.h"
#include "rtc_base/logging.h"
#include "system_wrappers/include/field_trial.h"
#include "system_wrappers/include/metrics.h"
namespace webrtc {
namespace {
constexpr TimeDelta kBweIncreaseInterval = TimeDelta::Millis<1000>();
constexpr TimeDelta kBweDecreaseInterval = TimeDelta::Millis<300>();
constexpr TimeDelta kStartPhase = TimeDelta::Millis<2000>();
constexpr TimeDelta kBweConverganceTime = TimeDelta::Millis<20000>();
constexpr int kLimitNumPackets = 20;
constexpr DataRate kDefaultMaxBitrate = DataRate::BitsPerSec<1000000000>();
constexpr TimeDelta kLowBitrateLogPeriod = TimeDelta::Millis<10000>();
constexpr TimeDelta kRtcEventLogPeriod = TimeDelta::Millis<5000>();
// Expecting that RTCP feedback is sent uniformly within [0.5, 1.5]s intervals.
constexpr TimeDelta kMaxRtcpFeedbackInterval = TimeDelta::Millis<5000>();
constexpr int kFeedbackTimeoutIntervals = 3;
constexpr TimeDelta kTimeoutInterval = TimeDelta::Millis<1000>();
constexpr float kDefaultLowLossThreshold = 0.02f;
constexpr float kDefaultHighLossThreshold = 0.1f;
constexpr DataRate kDefaultBitrateThreshold = DataRate::Zero();
struct UmaRampUpMetric {
const char* metric_name;
int bitrate_kbps;
};
const UmaRampUpMetric kUmaRampupMetrics[] = {
{"WebRTC.BWE.RampUpTimeTo500kbpsInMs", 500},
{"WebRTC.BWE.RampUpTimeTo1000kbpsInMs", 1000},
{"WebRTC.BWE.RampUpTimeTo2000kbpsInMs", 2000}};
const size_t kNumUmaRampupMetrics =
sizeof(kUmaRampupMetrics) / sizeof(kUmaRampupMetrics[0]);
const char kBweLosExperiment[] = "WebRTC-BweLossExperiment";
bool BweLossExperimentIsEnabled() {
std::string experiment_string =
webrtc::field_trial::FindFullName(kBweLosExperiment);
// The experiment is enabled iff the field trial string begins with "Enabled".
return experiment_string.find("Enabled") == 0;
}
bool ReadBweLossExperimentParameters(float* low_loss_threshold,
float* high_loss_threshold,
uint32_t* bitrate_threshold_kbps) {
RTC_DCHECK(low_loss_threshold);
RTC_DCHECK(high_loss_threshold);
RTC_DCHECK(bitrate_threshold_kbps);
std::string experiment_string =
webrtc::field_trial::FindFullName(kBweLosExperiment);
int parsed_values =
sscanf(experiment_string.c_str(), "Enabled-%f,%f,%u", low_loss_threshold,
high_loss_threshold, bitrate_threshold_kbps);
if (parsed_values == 3) {
RTC_CHECK_GT(*low_loss_threshold, 0.0f)
<< "Loss threshold must be greater than 0.";
RTC_CHECK_LE(*low_loss_threshold, 1.0f)
<< "Loss threshold must be less than or equal to 1.";
RTC_CHECK_GT(*high_loss_threshold, 0.0f)
<< "Loss threshold must be greater than 0.";
RTC_CHECK_LE(*high_loss_threshold, 1.0f)
<< "Loss threshold must be less than or equal to 1.";
RTC_CHECK_LE(*low_loss_threshold, *high_loss_threshold)
<< "The low loss threshold must be less than or equal to the high loss "
"threshold.";
RTC_CHECK_GE(*bitrate_threshold_kbps, 0)
<< "Bitrate threshold can't be negative.";
RTC_CHECK_LT(*bitrate_threshold_kbps,
std::numeric_limits<int>::max() / 1000)
<< "Bitrate must be smaller enough to avoid overflows.";
return true;
}
RTC_LOG(LS_WARNING) << "Failed to parse parameters for BweLossExperiment "
"experiment from field trial string. Using default.";
*low_loss_threshold = kDefaultLowLossThreshold;
*high_loss_threshold = kDefaultHighLossThreshold;
*bitrate_threshold_kbps = kDefaultBitrateThreshold.kbps();
return false;
}
} // namespace
LinkCapacityTracker::LinkCapacityTracker()
: tracking_rate("rate", TimeDelta::seconds(10)) {
ParseFieldTrial({&tracking_rate},
field_trial::FindFullName("WebRTC-Bwe-LinkCapacity"));
}
LinkCapacityTracker::~LinkCapacityTracker() {}
void LinkCapacityTracker::OnOveruse(DataRate acknowledged_rate,
Timestamp at_time) {
capacity_estimate_bps_ =
std::min(capacity_estimate_bps_, acknowledged_rate.bps<double>());
last_link_capacity_update_ = at_time;
}
void LinkCapacityTracker::OnStartingRate(DataRate start_rate) {
if (last_link_capacity_update_.IsInfinite())
capacity_estimate_bps_ = start_rate.bps<double>();
}
void LinkCapacityTracker::OnRateUpdate(DataRate acknowledged,
Timestamp at_time) {
if (acknowledged.bps() > capacity_estimate_bps_) {
TimeDelta delta = at_time - last_link_capacity_update_;
double alpha = delta.IsFinite() ? exp(-(delta / tracking_rate.Get())) : 0;
capacity_estimate_bps_ = alpha * capacity_estimate_bps_ +
(1 - alpha) * acknowledged.bps<double>();
}
last_link_capacity_update_ = at_time;
}
void LinkCapacityTracker::OnRttBackoff(DataRate backoff_rate,
Timestamp at_time) {
capacity_estimate_bps_ =
std::min(capacity_estimate_bps_, backoff_rate.bps<double>());
last_link_capacity_update_ = at_time;
}
DataRate LinkCapacityTracker::estimate() const {
return DataRate::bps(capacity_estimate_bps_);
}
RttBasedBackoff::RttBasedBackoff()
: rtt_limit_("limit", TimeDelta::PlusInfinity()),
drop_fraction_("fraction", 0.5),
drop_interval_("interval", TimeDelta::ms(300)),
persist_on_route_change_("persist"),
// By initializing this to plus infinity, we make sure that we never
// trigger rtt backoff unless packet feedback is enabled.
last_propagation_rtt_update_(Timestamp::PlusInfinity()),
last_propagation_rtt_(TimeDelta::Zero()) {
ParseFieldTrial({&rtt_limit_, &drop_fraction_, &drop_interval_,
&persist_on_route_change_},
field_trial::FindFullName("WebRTC-Bwe-MaxRttLimit"));
}
void RttBasedBackoff::OnRouteChange() {
if (!persist_on_route_change_) {
last_propagation_rtt_update_ = Timestamp::PlusInfinity();
last_propagation_rtt_ = TimeDelta::Zero();
}
}
void RttBasedBackoff::UpdatePropagationRtt(Timestamp at_time,
TimeDelta propagation_rtt) {
last_propagation_rtt_update_ = at_time;
last_propagation_rtt_ = propagation_rtt;
}
TimeDelta RttBasedBackoff::RttLowerBound(Timestamp at_time) const {
// TODO(srte): Use time since last unacknowledged packet for this.
TimeDelta time_since_rtt = at_time - last_propagation_rtt_update_;
return time_since_rtt + last_propagation_rtt_;
}
RttBasedBackoff::~RttBasedBackoff() = default;
SendSideBandwidthEstimation::SendSideBandwidthEstimation(RtcEventLog* event_log)
: lost_packets_since_last_loss_update_(0),
expected_packets_since_last_loss_update_(0),
current_bitrate_(DataRate::Zero()),
min_bitrate_configured_(
DataRate::bps(congestion_controller::GetMinBitrateBps())),
max_bitrate_configured_(kDefaultMaxBitrate),
last_low_bitrate_log_(Timestamp::MinusInfinity()),
has_decreased_since_last_fraction_loss_(false),
last_loss_feedback_(Timestamp::MinusInfinity()),
last_loss_packet_report_(Timestamp::MinusInfinity()),
last_timeout_(Timestamp::MinusInfinity()),
last_fraction_loss_(0),
last_logged_fraction_loss_(0),
last_round_trip_time_(TimeDelta::Zero()),
bwe_incoming_(DataRate::Zero()),
delay_based_bitrate_(DataRate::Zero()),
time_last_decrease_(Timestamp::MinusInfinity()),
first_report_time_(Timestamp::MinusInfinity()),
initially_lost_packets_(0),
bitrate_at_2_seconds_(DataRate::Zero()),
uma_update_state_(kNoUpdate),
uma_rtt_state_(kNoUpdate),
rampup_uma_stats_updated_(kNumUmaRampupMetrics, false),
event_log_(event_log),
last_rtc_event_log_(Timestamp::MinusInfinity()),
in_timeout_experiment_(
webrtc::field_trial::IsEnabled("WebRTC-FeedbackTimeout")),
low_loss_threshold_(kDefaultLowLossThreshold),
high_loss_threshold_(kDefaultHighLossThreshold),
bitrate_threshold_(kDefaultBitrateThreshold) {
RTC_DCHECK(event_log);
if (BweLossExperimentIsEnabled()) {
uint32_t bitrate_threshold_kbps;
if (ReadBweLossExperimentParameters(&low_loss_threshold_,
&high_loss_threshold_,
&bitrate_threshold_kbps)) {
RTC_LOG(LS_INFO) << "Enabled BweLossExperiment with parameters "
<< low_loss_threshold_ << ", " << high_loss_threshold_
<< ", " << bitrate_threshold_kbps;
bitrate_threshold_ = DataRate::kbps(bitrate_threshold_kbps);
}
}
}
SendSideBandwidthEstimation::~SendSideBandwidthEstimation() {}
void SendSideBandwidthEstimation::OnRouteChange() {
lost_packets_since_last_loss_update_ = 0;
expected_packets_since_last_loss_update_ = 0;
current_bitrate_ = DataRate::Zero();
min_bitrate_configured_ =
DataRate::bps(congestion_controller::GetMinBitrateBps());
max_bitrate_configured_ = kDefaultMaxBitrate;
last_low_bitrate_log_ = Timestamp::MinusInfinity();
has_decreased_since_last_fraction_loss_ = false;
last_loss_feedback_ = Timestamp::MinusInfinity();
last_loss_packet_report_ = Timestamp::MinusInfinity();
last_timeout_ = Timestamp::MinusInfinity();
last_fraction_loss_ = 0;
last_logged_fraction_loss_ = 0;
last_round_trip_time_ = TimeDelta::Zero();
bwe_incoming_ = DataRate::Zero();
delay_based_bitrate_ = DataRate::Zero();
time_last_decrease_ = Timestamp::MinusInfinity();
first_report_time_ = Timestamp::MinusInfinity();
initially_lost_packets_ = 0;
bitrate_at_2_seconds_ = DataRate::Zero();
uma_update_state_ = kNoUpdate;
uma_rtt_state_ = kNoUpdate;
last_rtc_event_log_ = Timestamp::MinusInfinity();
rtt_backoff_.OnRouteChange();
}
void SendSideBandwidthEstimation::SetBitrates(
absl::optional<DataRate> send_bitrate,
DataRate min_bitrate,
DataRate max_bitrate,
Timestamp at_time) {
SetMinMaxBitrate(min_bitrate, max_bitrate);
if (send_bitrate) {
link_capacity_.OnStartingRate(*send_bitrate);
SetSendBitrate(*send_bitrate, at_time);
}
}
void SendSideBandwidthEstimation::SetSendBitrate(DataRate bitrate,
Timestamp at_time) {
RTC_DCHECK(bitrate > DataRate::Zero());
// Reset to avoid being capped by the estimate.
delay_based_bitrate_ = DataRate::Zero();
if (loss_based_bandwidth_estimation_.Enabled()) {
loss_based_bandwidth_estimation_.MaybeReset(bitrate);
}
CapBitrateToThresholds(at_time, bitrate);
// Clear last sent bitrate history so the new value can be used directly
// and not capped.
min_bitrate_history_.clear();
}
void SendSideBandwidthEstimation::SetMinMaxBitrate(DataRate min_bitrate,
DataRate max_bitrate) {
min_bitrate_configured_ =
std::max(min_bitrate, congestion_controller::GetMinBitrate());
if (max_bitrate > DataRate::Zero() && max_bitrate.IsFinite()) {
max_bitrate_configured_ = std::max(min_bitrate_configured_, max_bitrate);
} else {
max_bitrate_configured_ = kDefaultMaxBitrate;
}
}
int SendSideBandwidthEstimation::GetMinBitrate() const {
return min_bitrate_configured_.bps<int>();
}
void SendSideBandwidthEstimation::CurrentEstimate(int* bitrate,
uint8_t* loss,
int64_t* rtt) const {
*bitrate = current_bitrate_.bps<int>();
*loss = last_fraction_loss_;
*rtt = last_round_trip_time_.ms<int64_t>();
}
DataRate SendSideBandwidthEstimation::GetEstimatedLinkCapacity() const {
return link_capacity_.estimate();
}
void SendSideBandwidthEstimation::UpdateReceiverEstimate(Timestamp at_time,
DataRate bandwidth) {
bwe_incoming_ = bandwidth;
CapBitrateToThresholds(at_time, current_bitrate_);
}
void SendSideBandwidthEstimation::UpdateDelayBasedEstimate(Timestamp at_time,
DataRate bitrate) {
if (acknowledged_rate_) {
if (bitrate < delay_based_bitrate_) {
link_capacity_.OnOveruse(*acknowledged_rate_, at_time);
}
}
delay_based_bitrate_ = bitrate;
CapBitrateToThresholds(at_time, current_bitrate_);
}
void SendSideBandwidthEstimation::SetAcknowledgedRate(
absl::optional<DataRate> acknowledged_rate,
Timestamp at_time) {
acknowledged_rate_ = acknowledged_rate;
if (acknowledged_rate && loss_based_bandwidth_estimation_.Enabled()) {
loss_based_bandwidth_estimation_.UpdateAcknowledgedBitrate(
*acknowledged_rate, at_time);
}
}
void SendSideBandwidthEstimation::IncomingPacketFeedbackVector(
const TransportPacketsFeedback& report) {
if (loss_based_bandwidth_estimation_.Enabled()) {
loss_based_bandwidth_estimation_.UpdateLossStatistics(
report.packet_feedbacks, report.feedback_time);
}
}
void SendSideBandwidthEstimation::UpdateReceiverBlock(uint8_t fraction_loss,
TimeDelta rtt,
int number_of_packets,
Timestamp at_time) {
const int kRoundingConstant = 128;
int packets_lost = (static_cast<int>(fraction_loss) * number_of_packets +
kRoundingConstant) >>
8;
UpdatePacketsLost(packets_lost, number_of_packets, at_time);
UpdateRtt(rtt, at_time);
}
void SendSideBandwidthEstimation::UpdatePacketsLost(int packets_lost,
int number_of_packets,
Timestamp at_time) {
last_loss_feedback_ = at_time;
if (first_report_time_.IsInfinite())
first_report_time_ = at_time;
// Check sequence number diff and weight loss report
if (number_of_packets > 0) {
// Accumulate reports.
lost_packets_since_last_loss_update_ += packets_lost;
expected_packets_since_last_loss_update_ += number_of_packets;
// Don't generate a loss rate until it can be based on enough packets.
if (expected_packets_since_last_loss_update_ < kLimitNumPackets)
return;
has_decreased_since_last_fraction_loss_ = false;
int64_t lost_q8 = lost_packets_since_last_loss_update_ << 8;
int64_t expected = expected_packets_since_last_loss_update_;
last_fraction_loss_ = std::min<int>(lost_q8 / expected, 255);
// Reset accumulators.
lost_packets_since_last_loss_update_ = 0;
expected_packets_since_last_loss_update_ = 0;
last_loss_packet_report_ = at_time;
UpdateEstimate(at_time);
}
UpdateUmaStatsPacketsLost(at_time, packets_lost);
}
void SendSideBandwidthEstimation::UpdateUmaStatsPacketsLost(Timestamp at_time,
int packets_lost) {
DataRate bitrate_kbps = DataRate::kbps((current_bitrate_.bps() + 500) / 1000);
for (size_t i = 0; i < kNumUmaRampupMetrics; ++i) {
if (!rampup_uma_stats_updated_[i] &&
bitrate_kbps.kbps() >= kUmaRampupMetrics[i].bitrate_kbps) {
RTC_HISTOGRAMS_COUNTS_100000(i, kUmaRampupMetrics[i].metric_name,
(at_time - first_report_time_).ms());
rampup_uma_stats_updated_[i] = true;
}
}
if (IsInStartPhase(at_time)) {
initially_lost_packets_ += packets_lost;
} else if (uma_update_state_ == kNoUpdate) {
uma_update_state_ = kFirstDone;
bitrate_at_2_seconds_ = bitrate_kbps;
RTC_HISTOGRAM_COUNTS("WebRTC.BWE.InitiallyLostPackets",
initially_lost_packets_, 0, 100, 50);
RTC_HISTOGRAM_COUNTS("WebRTC.BWE.InitialBandwidthEstimate",
bitrate_at_2_seconds_.kbps(), 0, 2000, 50);
} else if (uma_update_state_ == kFirstDone &&
at_time - first_report_time_ >= kBweConverganceTime) {
uma_update_state_ = kDone;
int bitrate_diff_kbps = std::max(
bitrate_at_2_seconds_.kbps<int>() - bitrate_kbps.kbps<int>(), 0);
RTC_HISTOGRAM_COUNTS("WebRTC.BWE.InitialVsConvergedDiff", bitrate_diff_kbps,
0, 2000, 50);
}
}
void SendSideBandwidthEstimation::UpdateRtt(TimeDelta rtt, Timestamp at_time) {
// Update RTT if we were able to compute an RTT based on this RTCP.
// FlexFEC doesn't send RTCP SR, which means we won't be able to compute RTT.
if (rtt > TimeDelta::Zero())
last_round_trip_time_ = rtt;
if (!IsInStartPhase(at_time) && uma_rtt_state_ == kNoUpdate) {
uma_rtt_state_ = kDone;
RTC_HISTOGRAM_COUNTS("WebRTC.BWE.InitialRtt", rtt.ms<int>(), 0, 2000, 50);
}
}
void SendSideBandwidthEstimation::UpdateEstimate(Timestamp at_time) {
DataRate new_bitrate = current_bitrate_;
if (rtt_backoff_.RttLowerBound(at_time) > rtt_backoff_.rtt_limit_) {
if (at_time - time_last_decrease_ >= rtt_backoff_.drop_interval_) {
time_last_decrease_ = at_time;
new_bitrate = current_bitrate_ * rtt_backoff_.drop_fraction_;
link_capacity_.OnRttBackoff(new_bitrate, at_time);
}
CapBitrateToThresholds(at_time, new_bitrate);
return;
}
// We trust the REMB and/or delay-based estimate during the first 2 seconds if
// we haven't had any packet loss reported, to allow startup bitrate probing.
if (last_fraction_loss_ == 0 && IsInStartPhase(at_time)) {
new_bitrate = std::max(bwe_incoming_, new_bitrate);
new_bitrate = std::max(delay_based_bitrate_, new_bitrate);
if (loss_based_bandwidth_estimation_.Enabled()) {
loss_based_bandwidth_estimation_.SetInitialBitrate(new_bitrate);
}
if (new_bitrate != current_bitrate_) {
min_bitrate_history_.clear();
if (loss_based_bandwidth_estimation_.Enabled()) {
min_bitrate_history_.push_back(std::make_pair(at_time, new_bitrate));
} else {
min_bitrate_history_.push_back(
std::make_pair(at_time, current_bitrate_));
}
CapBitrateToThresholds(at_time, new_bitrate);
return;
}
}
UpdateMinHistory(at_time);
if (last_loss_packet_report_.IsInfinite()) {
// No feedback received.
CapBitrateToThresholds(at_time, current_bitrate_);
return;
}
if (loss_based_bandwidth_estimation_.Enabled()) {
loss_based_bandwidth_estimation_.Update(
at_time, min_bitrate_history_.front().second, last_round_trip_time_);
new_bitrate = MaybeRampupOrBackoff(new_bitrate, at_time);
CapBitrateToThresholds(at_time, new_bitrate);
return;
}
TimeDelta time_since_loss_packet_report = at_time - last_loss_packet_report_;
TimeDelta time_since_loss_feedback = at_time - last_loss_feedback_;
if (time_since_loss_packet_report < 1.2 * kMaxRtcpFeedbackInterval) {
// We only care about loss above a given bitrate threshold.
float loss = last_fraction_loss_ / 256.0f;
// We only make decisions based on loss when the bitrate is above a
// threshold. This is a crude way of handling loss which is uncorrelated
// to congestion.
if (current_bitrate_ < bitrate_threshold_ || loss <= low_loss_threshold_) {
// Loss < 2%: Increase rate by 8% of the min bitrate in the last
// kBweIncreaseInterval.
// Note that by remembering the bitrate over the last second one can
// rampup up one second faster than if only allowed to start ramping
// at 8% per second rate now. E.g.:
// If sending a constant 100kbps it can rampup immediately to 108kbps
// whenever a receiver report is received with lower packet loss.
// If instead one would do: current_bitrate_ *= 1.08^(delta time),
// it would take over one second since the lower packet loss to achieve
// 108kbps.
new_bitrate =
DataRate::bps(min_bitrate_history_.front().second.bps() * 1.08 + 0.5);
// Add 1 kbps extra, just to make sure that we do not get stuck
// (gives a little extra increase at low rates, negligible at higher
// rates).
new_bitrate += DataRate::bps(1000);
} else if (current_bitrate_ > bitrate_threshold_) {
if (loss <= high_loss_threshold_) {
// Loss between 2% - 10%: Do nothing.
} else {
// Loss > 10%: Limit the rate decreases to once a kBweDecreaseInterval
// + rtt.
if (!has_decreased_since_last_fraction_loss_ &&
(at_time - time_last_decrease_) >=
(kBweDecreaseInterval + last_round_trip_time_)) {
time_last_decrease_ = at_time;
// Reduce rate:
// newRate = rate * (1 - 0.5*lossRate);
// where packetLoss = 256*lossRate;
new_bitrate =
DataRate::bps((current_bitrate_.bps() *
static_cast<double>(512 - last_fraction_loss_)) /
512.0);
has_decreased_since_last_fraction_loss_ = true;
}
}
}
} else if (time_since_loss_feedback >
kFeedbackTimeoutIntervals * kMaxRtcpFeedbackInterval &&
(last_timeout_.IsInfinite() ||
at_time - last_timeout_ > kTimeoutInterval)) {
if (in_timeout_experiment_) {
RTC_LOG(LS_WARNING) << "Feedback timed out ("
<< ToString(time_since_loss_feedback)
<< "), reducing bitrate.";
new_bitrate = new_bitrate * 0.8;
// Reset accumulators since we've already acted on missing feedback and
// shouldn't to act again on these old lost packets.
lost_packets_since_last_loss_update_ = 0;
expected_packets_since_last_loss_update_ = 0;
last_timeout_ = at_time;
}
}
CapBitrateToThresholds(at_time, new_bitrate);
}
void SendSideBandwidthEstimation::UpdatePropagationRtt(
Timestamp at_time,
TimeDelta propagation_rtt) {
rtt_backoff_.UpdatePropagationRtt(at_time, propagation_rtt);
}
bool SendSideBandwidthEstimation::IsInStartPhase(Timestamp at_time) const {
return first_report_time_.IsInfinite() ||
at_time - first_report_time_ < kStartPhase;
}
void SendSideBandwidthEstimation::UpdateMinHistory(Timestamp at_time) {
// Remove old data points from history.
// Since history precision is in ms, add one so it is able to increase
// bitrate if it is off by as little as 0.5ms.
while (!min_bitrate_history_.empty() &&
at_time - min_bitrate_history_.front().first + TimeDelta::ms(1) >
kBweIncreaseInterval) {
min_bitrate_history_.pop_front();
}
// Typical minimum sliding-window algorithm: Pop values higher than current
// bitrate before pushing it.
while (!min_bitrate_history_.empty() &&
current_bitrate_ <= min_bitrate_history_.back().second) {
min_bitrate_history_.pop_back();
}
min_bitrate_history_.push_back(std::make_pair(at_time, current_bitrate_));
}
DataRate SendSideBandwidthEstimation::MaybeRampupOrBackoff(DataRate new_bitrate,
Timestamp at_time) {
// TODO(crodbro): reuse this code in UpdateEstimate instead of current
// inlining of very similar functionality.
const TimeDelta time_since_loss_packet_report =
at_time - last_loss_packet_report_;
const TimeDelta time_since_loss_feedback = at_time - last_loss_feedback_;
if (time_since_loss_packet_report < 1.2 * kMaxRtcpFeedbackInterval) {
new_bitrate = min_bitrate_history_.front().second * 1.08;
new_bitrate += DataRate::bps(1000);
} else if (time_since_loss_feedback >
kFeedbackTimeoutIntervals * kMaxRtcpFeedbackInterval &&
(last_timeout_.IsInfinite() ||
at_time - last_timeout_ > kTimeoutInterval)) {
if (in_timeout_experiment_) {
RTC_LOG(LS_WARNING) << "Feedback timed out ("
<< ToString(time_since_loss_feedback)
<< "), reducing bitrate.";
new_bitrate = new_bitrate * 0.8;
// Reset accumulators since we've already acted on missing feedback and
// shouldn't to act again on these old lost packets.
lost_packets_since_last_loss_update_ = 0;
expected_packets_since_last_loss_update_ = 0;
last_timeout_ = at_time;
}
}
return new_bitrate;
}
void SendSideBandwidthEstimation::CapBitrateToThresholds(Timestamp at_time,
DataRate bitrate) {
if (bwe_incoming_ > DataRate::Zero() && bitrate > bwe_incoming_) {
bitrate = bwe_incoming_;
}
if (delay_based_bitrate_ > DataRate::Zero() &&
bitrate > delay_based_bitrate_) {
bitrate = delay_based_bitrate_;
}
if (loss_based_bandwidth_estimation_.Enabled() &&
loss_based_bandwidth_estimation_.GetEstimate() > DataRate::Zero()) {
bitrate = std::min(bitrate, loss_based_bandwidth_estimation_.GetEstimate());
}
if (bitrate > max_bitrate_configured_) {
bitrate = max_bitrate_configured_;
}
if (bitrate < min_bitrate_configured_) {
if (last_low_bitrate_log_.IsInfinite() ||
at_time - last_low_bitrate_log_ > kLowBitrateLogPeriod) {
RTC_LOG(LS_WARNING) << "Estimated available bandwidth "
<< ToString(bitrate)
<< " is below configured min bitrate "
<< ToString(min_bitrate_configured_) << ".";
last_low_bitrate_log_ = at_time;
}
bitrate = min_bitrate_configured_;
}
if (bitrate != current_bitrate_ ||
last_fraction_loss_ != last_logged_fraction_loss_ ||
at_time - last_rtc_event_log_ > kRtcEventLogPeriod) {
event_log_->Log(absl::make_unique<RtcEventBweUpdateLossBased>(
bitrate.bps(), last_fraction_loss_,
expected_packets_since_last_loss_update_));
last_logged_fraction_loss_ = last_fraction_loss_;
last_rtc_event_log_ = at_time;
}
current_bitrate_ = bitrate;
if (acknowledged_rate_) {
link_capacity_.OnRateUpdate(std::min(current_bitrate_, *acknowledged_rate_),
at_time);
}
}
} // namespace webrtc