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