commit e705f678abc12a4a7362965bd623a9fddd4271aa
author Harald Alvestrand <hta@webrtc.org> Thu Oct 02 07:32:39 2025
committer WebRTC LUCI CQ <webrtc-scoped@luci-project-accounts.iam.gserviceaccount.com> Thu Oct 02 09:02:17 2025
tree ba3bf4aa55b5e23c503d9cad058fd90c69edcecb
parent 66d580fda130131f22b0ed857235aac12b65cd71

Ensure that CCFB can be set when pr-answer is used.

Adds test

Bug: None
Change-Id: I7e01ab8a31d1620f4157e714490481c7337c69ad
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/413560
Reviewed-by: Per Kjellander <perkj@webrtc.org>
Commit-Queue: Harald Alvestrand <hta@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#45800}

pc/congestion_control_integrationtest.cc

diff --git a/pc/congestion_control_integrationtest.cc b/pc/congestion_control_integrationtest.cc
index cfde328..4eea57b 100644
--- a/pc/congestion_control_integrationtest.cc
+++ b/pc/congestion_control_integrationtest.cc
@@ -358,6 +358,40 @@
               Eq(0));
 }
 
+TEST_F(PeerConnectionCongestionControlTest, CcfbGetsUsedWithPrAnswer) {
+  SetFieldTrials("WebRTC-RFC8888CongestionControlFeedback/Enabled,offer:true/");
+  ASSERT_TRUE(CreatePeerConnectionWrappers());
+  ConnectFakeSignaling();
+  caller()->AddAudioVideoTracks();
+  callee()->SetGeneratedSdpMunger(
+      [](std::unique_ptr<SessionDescriptionInterface>& sdp) {
+        SetSdpType(sdp, SdpType::kPrAnswer);
+      });
+  caller()->CreateAndSetAndSignalOffer();
+  ASSERT_THAT(WaitUntil(
+                  [&] {
+                    return caller()->pc()->signaling_state() ==
+                           PeerConnectionInterface::kHaveRemotePrAnswer;
+                  },
+                  IsTrue()),
+              IsRtcOk());
+  MediaExpectations media_expectations;
+  media_expectations.CalleeExpectsSomeAudio();
+  media_expectations.CalleeExpectsSomeVideo();
+  ASSERT_TRUE(ExpectNewFrames(media_expectations));
+  auto pc_internal = caller()->pc_internal();
+  EXPECT_THAT(
+      WaitUntil(
+          [&] {
+            return pc_internal->FeedbackAccordingToRfc8888CountForTesting();
+          },
+          Gt(0)),
+      IsRtcOk());
+  // There should be no transport-cc generated.
+  EXPECT_THAT(pc_internal->FeedbackAccordingToTransportCcCountForTesting(),
+              Eq(0));
+}
+
 TEST_F(PeerConnectionCongestionControlTest, TransportCcGetsUsed) {
   SetFieldTrials("WebRTC-RFC8888CongestionControlFeedback/Disabled/");
   ASSERT_TRUE(CreatePeerConnectionWrappers());

pc/sdp_offer_answer.cc

diff --git a/pc/sdp_offer_answer.cc b/pc/sdp_offer_answer.cc
index d106e00..f572c1a 100644
--- a/pc/sdp_offer_answer.cc
+++ b/pc/sdp_offer_answer.cc
@@ -5099,8 +5099,8 @@
     // If local and remote are both set, we assume that it's safe to trigger
     // CCFB.
     if (pc_->trials().IsEnabled("WebRTC-RFC8888CongestionControlFeedback")) {
-      if (type == SdpType::kAnswer && local_description() &&
-          remote_description()) {
+      if ((type == SdpType::kAnswer || type == SdpType::kPrAnswer) &&
+          local_description() && remote_description()) {
         std::optional<RtcpFeedbackType> remote_preferred_rtcp_cc_ack_type;
         // Verify that the remote agrees on congestion control feedback format.
         for (const auto& content :