From 13b5eb7c471ba88da9650c3e58e74e853f9c760c Mon Sep 17 00:00:00 2001
From: Philipp Hancke <phancke@microsoft.com>
Date: Wed, 4 Oct 2023 16:20:05 +0200
Subject: [PATCH] stats: ensure rtx ssrc is associated with primary ssrc
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BUG=webrtc:15529

Change-Id: I3623eede7fc7890677516d78f3ef7a89a287eb8a
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/322221
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Philipp Hancke <phancke@microsoft.com>
Reviewed-by: Henrik Boström <hbos@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#40873}
---
 ...er_connection_encodings_integrationtest.cc | 41 +++++++++++++++++++
 pc/rtc_stats_collector.cc                     |  3 +-
 2 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/pc/peer_connection_encodings_integrationtest.cc b/pc/peer_connection_encodings_integrationtest.cc
index 5b25e293cd..4e502f73d7 100644
--- a/pc/peer_connection_encodings_integrationtest.cc
+++ b/pc/peer_connection_encodings_integrationtest.cc
@@ -924,6 +924,47 @@ TEST_F(PeerConnectionEncodingsIntegrationTest, VP9_TargetBitrate_StandardL1T3) {
   EXPECT_LE(target_bitrate.kbps(), kVp9ExpectedMaxBitrateForL1T3.kbps());
 }
 
+TEST_F(PeerConnectionEncodingsIntegrationTest,
+       SimulcastProducesUniqueSsrcAndRtxSsrcs) {
+  rtc::scoped_refptr<PeerConnectionTestWrapper> local_pc_wrapper = CreatePc();
+  rtc::scoped_refptr<PeerConnectionTestWrapper> remote_pc_wrapper = CreatePc();
+  ExchangeIceCandidates(local_pc_wrapper, remote_pc_wrapper);
+
+  std::vector<cricket::SimulcastLayer> layers =
+      CreateLayers({"f", "h", "q"}, /*active=*/true);
+  rtc::scoped_refptr<RtpTransceiverInterface> transceiver =
+      AddTransceiverWithSimulcastLayers(local_pc_wrapper, remote_pc_wrapper,
+                                        layers);
+  std::vector<RtpCodecCapability> codecs =
+      GetCapabilitiesAndRestrictToCodec(local_pc_wrapper, "VP8");
+  transceiver->SetCodecPreferences(codecs);
+
+  NegotiateWithSimulcastTweaks(local_pc_wrapper, remote_pc_wrapper);
+  local_pc_wrapper->WaitForConnection();
+  remote_pc_wrapper->WaitForConnection();
+
+  // Wait until media is flowing on all three layers.
+  // Ramp up time is needed before all three layers are sending.
+  ASSERT_TRUE_WAIT(HasOutboundRtpBytesSent(local_pc_wrapper, 3u),
+                   kLongTimeoutForRampingUp.ms());
+  // Verify SSRCs and RTX SSRCs.
+  rtc::scoped_refptr<const RTCStatsReport> report = GetStats(local_pc_wrapper);
+  std::vector<const RTCOutboundRtpStreamStats*> outbound_rtps =
+      report->GetStatsOfType<RTCOutboundRtpStreamStats>();
+  ASSERT_THAT(outbound_rtps, SizeIs(3u));
+
+  std::set<uint32_t> ssrcs;
+  std::set<uint32_t> rtx_ssrcs;
+  for (const auto& outbound_rtp : outbound_rtps) {
+    ASSERT_TRUE(outbound_rtp->ssrc.has_value());
+    ASSERT_TRUE(outbound_rtp->rtx_ssrc.has_value());
+    ssrcs.insert(*outbound_rtp->ssrc);
+    rtx_ssrcs.insert(*outbound_rtp->rtx_ssrc);
+  }
+  EXPECT_EQ(ssrcs.size(), 3u);
+  EXPECT_EQ(rtx_ssrcs.size(), 3u);
+}
+
 TEST_F(PeerConnectionEncodingsIntegrationTest,
        EncodingParameterCodecIsEmptyWhenCreatedAudio) {
   rtc::scoped_refptr<PeerConnectionTestWrapper> local_pc_wrapper = CreatePc();
diff --git a/pc/rtc_stats_collector.cc b/pc/rtc_stats_collector.cc
index c191f4d65e..0797ba2a76 100644
--- a/pc/rtc_stats_collector.cc
+++ b/pc/rtc_stats_collector.cc
@@ -839,7 +839,8 @@ CreateOutboundRTPStreamStatsFromVideoSenderInfo(
   }
   for (const auto& ssrc_group : video_sender_info.ssrc_groups) {
     if (ssrc_group.semantics == cricket::kFidSsrcGroupSemantics &&
-        ssrc_group.ssrcs.size() == 2) {
+        ssrc_group.ssrcs.size() == 2 &&
+        video_sender_info.ssrc() == ssrc_group.ssrcs[0]) {
       outbound_video->rtx_ssrc = ssrc_group.ssrcs[1];
     }
   }