From 33d2a91737946a5aa43864f0aa4136907b2d41fe Mon Sep 17 00:00:00 2001
From: Ilya Nikolaevskiy <ilnik@webrtc.org>
Date: Tue, 2 Apr 2019 11:05:03 +0200
Subject: [PATCH] Fix target bitrate RTCP messages behavior for SVC streams
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This is a better solution than https://webrtc-review.googlesource.com/c/src/+/129929 (which got reverted).
This CL instead filters out unused SSRCs from RtpConfig for RtpVideoSender.

Bug: webrtc:10485
Change-Id: Iaa8d07681419a2387c8253eb38e08a0828e9e688
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/130505
Reviewed-by: Niels Moller <nisse@webrtc.org>
Reviewed-by: Erik Språng <sprang@webrtc.org>
Commit-Queue: Ilya Nikolaevskiy <ilnik@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#27433}
---
 media/engine/webrtc_video_engine.cc          | 18 +++++++++--
 media/engine/webrtc_video_engine_unittest.cc | 32 +++++++++++++++++++-
 2 files changed, 47 insertions(+), 3 deletions(-)

diff --git a/media/engine/webrtc_video_engine.cc b/media/engine/webrtc_video_engine.cc
index acbc36f701..ca357be7e2 100644
--- a/media/engine/webrtc_video_engine.cc
+++ b/media/engine/webrtc_video_engine.cc
@@ -1996,8 +1996,13 @@ void WebRtcVideoChannel::WebRtcVideoSendStream::UpdateSendState() {
   RTC_DCHECK_RUN_ON(&thread_checker_);
   if (sending_) {
     RTC_DCHECK(stream_ != nullptr);
-    std::vector<bool> active_layers(rtp_parameters_.encodings.size());
-    for (size_t i = 0; i < active_layers.size(); ++i) {
+    size_t num_layers = rtp_parameters_.encodings.size();
+    if (parameters_.encoder_config.number_of_streams == 1) {
+      // SVC is used. Only one simulcast layer is present.
+      num_layers = 1;
+    }
+    std::vector<bool> active_layers(num_layers);
+    for (size_t i = 0; i < num_layers; ++i) {
       active_layers[i] = rtp_parameters_.encodings[i].active;
     }
     // This updates what simulcast layers are sending, and possibly starts
@@ -2302,6 +2307,15 @@ void WebRtcVideoChannel::WebRtcVideoSendStream::RecreateWebRtcStream() {
                            "payload type the set codec. Ignoring RTX.";
     config.rtp.rtx.ssrcs.clear();
   }
+  if (parameters_.encoder_config.number_of_streams == 1) {
+    // SVC is used instead of simulcast. Remove unnecessary SSRCs.
+    if (config.rtp.ssrcs.size() > 1) {
+      config.rtp.ssrcs.resize(1);
+      if (config.rtp.rtx.ssrcs.size() > 1) {
+        config.rtp.rtx.ssrcs.resize(1);
+      }
+    }
+  }
   stream_ = call_->CreateVideoSendStream(std::move(config),
                                          parameters_.encoder_config.Copy());
 
diff --git a/media/engine/webrtc_video_engine_unittest.cc b/media/engine/webrtc_video_engine_unittest.cc
index da205e1219..58c97ac3a3 100644
--- a/media/engine/webrtc_video_engine_unittest.cc
+++ b/media/engine/webrtc_video_engine_unittest.cc
@@ -3063,7 +3063,6 @@ TEST_F(Vp9SettingsTest, MultipleSsrcsEnablesSvc) {
       AddSendStream(CreateSimStreamParams("cname", ssrcs));
 
   webrtc::VideoSendStream::Config config = stream->GetConfig().Copy();
-  EXPECT_EQ(ssrcs.size(), config.rtp.ssrcs.size());
 
   webrtc::test::FrameForwarder frame_forwarder;
   EXPECT_TRUE(channel_->SetVideoSend(ssrcs[0], nullptr, &frame_forwarder));
@@ -3082,6 +3081,36 @@ TEST_F(Vp9SettingsTest, MultipleSsrcsEnablesSvc) {
   EXPECT_TRUE(channel_->SetVideoSend(ssrcs[0], nullptr, nullptr));
 }
 
+TEST_F(Vp9SettingsTest, SvcModeCreatesSingleRtpStream) {
+  cricket::VideoSendParameters parameters;
+  parameters.codecs.push_back(GetEngineCodec("VP9"));
+  ASSERT_TRUE(channel_->SetSendParameters(parameters));
+
+  std::vector<uint32_t> ssrcs = MAKE_VECTOR(kSsrcs3);
+
+  FakeVideoSendStream* stream =
+      AddSendStream(CreateSimStreamParams("cname", ssrcs));
+
+  webrtc::VideoSendStream::Config config = stream->GetConfig().Copy();
+
+  // Despite 3 ssrcs provided, single layer is used.
+  EXPECT_EQ(1u, config.rtp.ssrcs.size());
+
+  webrtc::test::FrameForwarder frame_forwarder;
+  EXPECT_TRUE(channel_->SetVideoSend(ssrcs[0], nullptr, &frame_forwarder));
+  channel_->SetSend(true);
+
+  frame_forwarder.IncomingCapturedFrame(frame_source_.GetFrame());
+
+  webrtc::VideoCodecVP9 vp9_settings;
+  ASSERT_TRUE(stream->GetVp9Settings(&vp9_settings)) << "No VP9 config set.";
+
+  const size_t kNumSpatialLayers = ssrcs.size();
+  EXPECT_EQ(vp9_settings.numberOfSpatialLayers, kNumSpatialLayers);
+
+  EXPECT_TRUE(channel_->SetVideoSend(ssrcs[0], nullptr, nullptr));
+}
+
 TEST_F(Vp9SettingsTest, AllEncodingParametersCopied) {
   cricket::VideoSendParameters send_parameters;
   send_parameters.codecs.push_back(GetEngineCodec("VP9"));
@@ -7090,6 +7119,7 @@ class WebRtcVideoChannelSimulcastTest : public testing::Test {
 
     std::vector<webrtc::VideoStream> video_streams = stream->GetVideoStreams();
     ASSERT_EQ(expected_num_streams, video_streams.size());
+    EXPECT_LE(expected_num_streams, stream->GetConfig().rtp.ssrcs.size());
 
     std::vector<webrtc::VideoStream> expected_streams;
     if (conference_mode) {