Adds stable bandwidth estimate to GoogCC.
The intention is to provide a bandwidth estimate that only updates if
the actual available bandwidth is known to have changed. This will be
used in media streams to avoid changing the configuration (such as
frame size, audio frame length etc), just because the control target
rate changed.
Bug: webrtc:9718
Change-Id: I17ba5a2f9e5bd408a71f89c690d45541655a68e2
Reviewed-on: https://webrtc-review.googlesource.com/c/107726
Commit-Queue: Sebastian Jansson <srte@webrtc.org>
Reviewed-by: Björn Terelius <terelius@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25772}diff --git a/modules/bitrate_controller/send_side_bandwidth_estimation.cc b/modules/bitrate_controller/send_side_bandwidth_estimation.cc
index 4694aa6..394c147 100644
--- a/modules/bitrate_controller/send_side_bandwidth_estimation.cc
+++ b/modules/bitrate_controller/send_side_bandwidth_estimation.cc
@@ -104,6 +104,48 @@
}
} // 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),
@@ -220,8 +262,10 @@
DataRate max_bitrate,
Timestamp at_time) {
SetMinMaxBitrate(min_bitrate, max_bitrate);
- if (send_bitrate)
+ if (send_bitrate) {
+ link_capacity_.OnStartingRate(*send_bitrate);
SetSendBitrate(*send_bitrate, at_time);
+ }
}
void SendSideBandwidthEstimation::SetSendBitrate(DataRate bitrate,
@@ -261,6 +305,10 @@
*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;
@@ -269,21 +317,31 @@
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::IncomingPacketFeedbackVector(
- const TransportPacketsFeedback& report,
- absl::optional<DataRate> acked_bitrate) {
- if (!loss_based_bandwidth_estimation_.Enabled())
- return;
- if (acked_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(
- *acked_bitrate, report.feedback_time);
+ *acknowledged_rate, at_time);
}
- loss_based_bandwidth_estimation_.UpdateLossStatistics(report.packet_feedbacks,
- report.feedback_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,
@@ -378,6 +436,7 @@
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;
@@ -580,5 +639,10 @@
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
diff --git a/modules/bitrate_controller/send_side_bandwidth_estimation.h b/modules/bitrate_controller/send_side_bandwidth_estimation.h
index ab43c52..b016fab 100644
--- a/modules/bitrate_controller/send_side_bandwidth_estimation.h
+++ b/modules/bitrate_controller/send_side_bandwidth_estimation.h
@@ -31,6 +31,22 @@
class RtcEventLog;
+class LinkCapacityTracker {
+ public:
+ LinkCapacityTracker();
+ ~LinkCapacityTracker();
+ void OnOveruse(DataRate acknowledged_rate, Timestamp at_time);
+ void OnStartingRate(DataRate start_rate);
+ void OnRateUpdate(DataRate acknowledged, Timestamp at_time);
+ void OnRttBackoff(DataRate backoff_rate, Timestamp at_time);
+ DataRate estimate() const;
+
+ private:
+ FieldTrialParameter<TimeDelta> tracking_rate;
+ double capacity_estimate_bps_ = 0;
+ Timestamp last_link_capacity_update_ = Timestamp::MinusInfinity();
+};
+
class RttBasedBackoff {
public:
RttBasedBackoff();
@@ -57,7 +73,7 @@
void OnRouteChange();
void CurrentEstimate(int* bitrate, uint8_t* loss, int64_t* rtt) const;
-
+ DataRate GetEstimatedLinkCapacity() const;
// Call periodically to update estimate.
void UpdateEstimate(Timestamp at_time);
void OnSentPacket(SentPacket sent_packet);
@@ -90,8 +106,9 @@
void SetSendBitrate(DataRate bitrate, Timestamp at_time);
void SetMinMaxBitrate(DataRate min_bitrate, DataRate max_bitrate);
int GetMinBitrate() const;
- void IncomingPacketFeedbackVector(const TransportPacketsFeedback& report,
- absl::optional<DataRate> acked_bitrate);
+ void SetAcknowledgedRate(absl::optional<DataRate> acknowledged_rate,
+ Timestamp at_time);
+ void IncomingPacketFeedbackVector(const TransportPacketsFeedback& report);
private:
enum UmaState { kNoUpdate, kFirstDone, kDone };
@@ -112,6 +129,7 @@
void CapBitrateToThresholds(Timestamp at_time, DataRate bitrate);
RttBasedBackoff rtt_backoff_;
+ LinkCapacityTracker link_capacity_;
std::deque<std::pair<Timestamp, DataRate> > min_bitrate_history_;
@@ -119,6 +137,7 @@
int lost_packets_since_last_loss_update_;
int expected_packets_since_last_loss_update_;
+ absl::optional<DataRate> acknowledged_rate_;
DataRate current_bitrate_;
DataRate min_bitrate_configured_;
DataRate max_bitrate_configured_;