tor-browser

commit e401f4eac294d11b6d3947180615067765e02753
parent e46d0861f906b7871d68735a0a2bf2017b234dd0
Author: Michael Froman <mfroman@mozilla.com>
Date:   Wed,  8 Oct 2025 17:01:40 -0500

Bug 1993083 - Vendor libwebrtc from 4f422cb71c

Upstream commit: https://webrtc.googlesource.com/src/+/4f422cb71cf3de656d16fd79b791414813ef9c8e
    Fix loss based BWE to avoid unnecessary paddings.

    When the delay-based estimate and a 2% bandwidth-increase candidate had the same kbps but different bps, the algorithm selected the latter.
    This resulted in a lower bandwidth selection than the delay-based estimate, triggering unnecessary padding.

    With this change, the higher bandwidth candidate will be selected if having the same kbps.

    Bug: webrtc:12707,webrtc:427648364
    Change-Id: I1ed042689317c768b773d7e6f0819690c38f0e56
    Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/398080
    Commit-Queue: Diep Bui <diepbp@webrtc.org>
    Reviewed-by: Per Kjellander <perkj@webrtc.org>
    Cr-Commit-Position: refs/heads/main@{#45027}

Diffstat:
M
third_party/libwebrtc/README.mozilla.last-vendor
 | 
4
++--
M
third_party/libwebrtc/modules/congestion_controller/goog_cc/loss_based_bwe_v2.cc
 | 
7
++++++-
M
third_party/libwebrtc/modules/congestion_controller/goog_cc/loss_based_bwe_v2_test.cc
 | 
25
+++++++++++++++++++++++++

3 files changed, 33 insertions(+), 3 deletions(-)
diff --git a/third_party/libwebrtc/README.mozilla.last-vendor b/third_party/libwebrtc/README.mozilla.last-vendor
@@ -1,4 +1,4 @@
 # ./mach python dom/media/webrtc/third_party_build/vendor-libwebrtc.py --from-local /home/mfroman/mozilla/elm/.moz-fast-forward/moz-libwebrtc --commit mozpatches libwebrtc
-libwebrtc updated from /home/mfroman/mozilla/elm/.moz-fast-forward/moz-libwebrtc commit mozpatches on 2025-10-08T22:00:29.428940+00:00.
+libwebrtc updated from /home/mfroman/mozilla/elm/.moz-fast-forward/moz-libwebrtc commit mozpatches on 2025-10-08T22:01:33.102578+00:00.
 # base of lastest vendoring
-43f724dcac
+4f422cb71c
diff --git a/third_party/libwebrtc/modules/congestion_controller/goog_cc/loss_based_bwe_v2.cc b/third_party/libwebrtc/modules/congestion_controller/goog_cc/loss_based_bwe_v2.cc
@@ -224,7 +224,12 @@ void LossBasedBweV2::UpdateBandwidthEstimate(
     NewtonsMethodUpdate(candidate);
 
     const double candidate_objective = GetObjective(candidate);
-    if (candidate_objective > objective_max) {
+    if (candidate_objective > objective_max ||
+        (candidate_objective == objective_max &&
+         candidate.loss_limited_bandwidth >
+             best_candidate.loss_limited_bandwidth)) {
+      // Select the candidate with the highest objective or the one with the
+      // same objective but higher bandwidth if they are tied.
       objective_max = candidate_objective;
       best_candidate = candidate;
     }
diff --git a/third_party/libwebrtc/modules/congestion_controller/goog_cc/loss_based_bwe_v2_test.cc b/third_party/libwebrtc/modules/congestion_controller/goog_cc/loss_based_bwe_v2_test.cc
@@ -1793,5 +1793,30 @@ TEST_F(LossBasedBweV2Test,
       kStartBitrate);
 }
 
+TEST_F(LossBasedBweV2Test, SelectHigherCandidateIfHavingSameObjective) {
+  FieldTrials key_value_config = ShortObservationConfig("");
+  LossBasedBweV2 loss_based_bandwidth_estimator(&key_value_config);
+  const DataRate kStartBitrate = DataRate::KilobitsPerSec(1000);
+  loss_based_bandwidth_estimator.SetBandwidthEstimate(kStartBitrate);
+  std::vector<PacketResult> enough_feedback_01 =
+      CreatePacketResultsWithReceivedPackets(
+          /*first_packet_timestamp=*/Timestamp::Zero());
+  std::vector<PacketResult> enough_feedback_02 =
+      CreatePacketResultsWithReceivedPackets(
+          /*first_packet_timestamp=*/Timestamp::Zero() +
+          kObservationDurationLowerBound);
+  loss_based_bandwidth_estimator.UpdateBandwidthEstimate(enough_feedback_01,
+                                                         kStartBitrate,
+                                                         /*in_alr=*/false);
+  DataRate delay_based_estimate =
+      DataRate::BytesPerSec(kStartBitrate.bytes_per_sec() * 1.02 + 1);
+  loss_based_bandwidth_estimator.UpdateBandwidthEstimate(enough_feedback_02,
+                                                         delay_based_estimate,
+                                                         /*in_alr=*/false);
+
+  EXPECT_EQ(
+      loss_based_bandwidth_estimator.GetLossBasedResult().bandwidth_estimate,
+      delay_based_estimate);
+}
 }  // namespace
 }  // namespace webrtc