In RtcpTransceiver avoid generating rtcp sender reports for inactive senders

Bug: webrtc:8239
Change-Id: I97d50c628db04c56669179ab7039a3fe3bd61d34
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/251901
Reviewed-by: Emil Lundmark <lndmrk@webrtc.org>
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#36030}

modules/rtp_rtcp/source/rtcp_transceiver_impl.cc

@@ -56,6 +56,7 @@ struct RtcpTransceiverImpl::RemoteSenderState {
 
 struct RtcpTransceiverImpl::LocalSenderState {
   uint32_t ssrc;
+  size_t last_num_sent_bytes = 0;
   RtpStreamRtcpHandler* handler = nullptr;
 };
 
@@ -527,6 +528,17 @@ RtcpTransceiverImpl::CompoundPacketInfo RtcpTransceiverImpl::FillReports(
     LocalSenderState& rtp_sender = *it;
     RtpStreamRtcpHandler::RtpStats stats = rtp_sender.handler->SentStats();
 
+    if (stats.num_sent_bytes() < rtp_sender.last_num_sent_bytes) {
+      RTC_LOG(LS_ERROR) << "Inconsistent SR for SSRC " << rtp_sender.ssrc
+                        << ". Number of total sent bytes decreased.";
+      rtp_sender.last_num_sent_bytes = 0;
+    }
+    if (stats.num_sent_bytes() == rtp_sender.last_num_sent_bytes) {
+      // Skip because no RTP packet was send for this SSRC since last report.
+      continue;
+    }
+    rtp_sender.last_num_sent_bytes = stats.num_sent_bytes();
+
     last_handled_sender_it = it;
     rtcp::SenderReport sender_report;
     sender_report.SetSenderSsrc(rtp_sender.ssrc);

modules/rtp_rtcp/source/rtcp_transceiver_impl_unittest.cc

@@ -69,7 +69,21 @@ class MockMediaReceiverRtcpObserver : public MediaReceiverRtcpObserver {
 
 class MockRtpStreamRtcpHandler : public RtpStreamRtcpHandler {
  public:
+  MockRtpStreamRtcpHandler() {
+    // With each next call increase number of sent packets and bytes to simulate
+    // active RTP sender.
+    ON_CALL(*this, SentStats).WillByDefault([this] {
+      RtpStats stats;
+      stats.set_num_sent_packets(++num_calls_);
+      stats.set_num_sent_bytes(1'000 * num_calls_);
+      return stats;
+    });
+  }
+
   MOCK_METHOD(RtpStats, SentStats, (), (override));
+
+ private:
+  int num_calls_ = 0;
 };
 
 class MockNetworkLinkRtcpObserver : public NetworkLinkRtcpObserver {
@@ -1472,5 +1486,56 @@ TEST(RtcpTransceiverImplTest, RotatesSendersWhenAllSenderReportDoNotFit) {
   }
 }
 
+TEST(RtcpTransceiverImplTest, SkipsSenderReportForInactiveSender) {
+  static constexpr uint32_t kSenderSsrc[] = {12345, 23456};
+  RtcpTransceiverConfig config = DefaultTestConfig();
+  RtcpPacketParser rtcp_parser;
+  RtcpParserTransport transport(&rtcp_parser);
+  config.outgoing_transport = &transport;
+  RtcpTransceiverImpl rtcp_transceiver(config);
+
+  RtpStreamRtcpHandler::RtpStats sender_stats[2];
+  NiceMock<MockRtpStreamRtcpHandler> sender[2];
+  ON_CALL(sender[0], SentStats).WillByDefault([&] { return sender_stats[0]; });
+  ON_CALL(sender[1], SentStats).WillByDefault([&] { return sender_stats[1]; });
+  rtcp_transceiver.AddMediaSender(kSenderSsrc[0], &sender[0]);
+  rtcp_transceiver.AddMediaSender(kSenderSsrc[1], &sender[1]);
+
+  // Start with both senders beeing active.
+  sender_stats[0].set_num_sent_packets(10);
+  sender_stats[0].set_num_sent_bytes(1'000);
+  sender_stats[1].set_num_sent_packets(5);
+  sender_stats[1].set_num_sent_bytes(2'000);
+  rtcp_transceiver.SendCompoundPacket();
+  EXPECT_EQ(transport.num_packets(), 1);
+  EXPECT_EQ(rtcp_parser.sender_report()->num_packets(), 2);
+
+  // Keep 1st sender active, but make 2nd second look inactive by returning the
+  // same RtpStats.
+  sender_stats[0].set_num_sent_packets(15);
+  sender_stats[0].set_num_sent_bytes(2'000);
+  rtcp_transceiver.SendCompoundPacket();
+  EXPECT_EQ(transport.num_packets(), 2);
+  EXPECT_EQ(rtcp_parser.sender_report()->num_packets(), 3);
+  EXPECT_EQ(rtcp_parser.sender_report()->sender_ssrc(), kSenderSsrc[0]);
+
+  // Swap active sender.
+  sender_stats[1].set_num_sent_packets(20);
+  sender_stats[1].set_num_sent_bytes(3'000);
+  rtcp_transceiver.SendCompoundPacket();
+  EXPECT_EQ(transport.num_packets(), 3);
+  EXPECT_EQ(rtcp_parser.sender_report()->num_packets(), 4);
+  EXPECT_EQ(rtcp_parser.sender_report()->sender_ssrc(), kSenderSsrc[1]);
+
+  // Activate both senders again.
+  sender_stats[0].set_num_sent_packets(20);
+  sender_stats[0].set_num_sent_bytes(3'000);
+  sender_stats[1].set_num_sent_packets(25);
+  sender_stats[1].set_num_sent_bytes(3'500);
+  rtcp_transceiver.SendCompoundPacket();
+  EXPECT_EQ(transport.num_packets(), 4);
+  EXPECT_EQ(rtcp_parser.sender_report()->num_packets(), 6);
+}
+
 }  // namespace
 }  // namespace webrtc