[WebRtcVideoReceiveStream] Add SetLossNotificationEnabled

...to allow for turning on/off loss notifications for video receive
streams without tearing down and recreating the whole stream.

Bug: webrtc:11993
Change-Id: Ia961bd343ce816ffe3414f11e3a58bb3c235307c
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/269252
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Commit-Queue: Tomas Gunnarsson <tommi@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#37688}

call/video_receive_stream.h

@@ -294,6 +294,10 @@ class VideoReceiveStreamInterface : public MediaReceiveStreamInterface {
   // thread` but will be `network thread`.
   virtual void SetFlexFecProtection(RtpPacketSinkInterface* flexfec_sink) = 0;
 
+  // Turns on/off loss notifications. Must be called on the packet delivery
+  // thread.
+  virtual void SetLossNotificationEnabled(bool enabled) = 0;
+
  protected:
   virtual ~VideoReceiveStreamInterface() {}
 };

media/engine/fake_webrtc_call.h

@@ -289,6 +289,10 @@ class FakeVideoReceiveStream final
     config_.rtp.protected_by_flexfec = (sink != nullptr);
   }
 
+  void SetLossNotificationEnabled(bool enabled) override {
+    config_.rtp.lntf.enabled = enabled;
+  }
+
   void Start() override;
   void Stop() override;
 

media/engine/webrtc_video_engine.cc

@@ -2985,7 +2985,7 @@ bool WebRtcVideoChannel::WebRtcVideoReceiveStream::ReconfigureCodecs(
   const bool has_lntf = HasLntf(codec.codec);
   if (config_.rtp.lntf.enabled != has_lntf) {
     config_.rtp.lntf.enabled = has_lntf;
-    recreate_needed = true;
+    stream_->SetLossNotificationEnabled(has_lntf);
   }
 
   const int rtp_history_ms = HasNack(codec.codec) ? kNackHistoryMs : 0;
@@ -3060,23 +3060,26 @@ void WebRtcVideoChannel::WebRtcVideoReceiveStream::SetFeedbackParameters(
     }
   }
 
+  config_.rtp.lntf.enabled = lntf_enabled;
+  stream_->SetLossNotificationEnabled(lntf_enabled);
+
   int nack_history_ms =
       nack_enabled ? rtx_time != -1 ? rtx_time : kNackHistoryMs : 0;
-  if (config_.rtp.lntf.enabled == lntf_enabled &&
-      config_.rtp.nack.rtp_history_ms == nack_history_ms) {
+  if (config_.rtp.nack.rtp_history_ms == nack_history_ms) {
     RTC_LOG(LS_INFO)
         << "Ignoring call to SetFeedbackParameters because parameters are "
-           "unchanged; lntf="
-        << lntf_enabled << ", nack=" << nack_enabled
-        << ", rtx_time=" << rtx_time;
+           "unchanged; nack="
+        << nack_enabled << ", rtx_time=" << rtx_time;
     return;
   }
 
-  config_.rtp.lntf.enabled = lntf_enabled;
+  RTC_LOG_F(LS_INFO) << "(recv) because of SetFeedbackParameters; nack="
+                     << nack_enabled << ". rtp_history_ms "
+                     << config_.rtp.nack.rtp_history_ms << "->"
+                     << nack_history_ms;
+
   config_.rtp.nack.rtp_history_ms = nack_history_ms;
 
-  RTC_LOG_F(LS_INFO) << "(recv) because of SetFeedbackParameters; nack="
-                     << nack_enabled;
   RecreateReceiveStream();
 }
 

video/rtp_video_stream_receiver2.cc

@@ -202,6 +202,11 @@ void RtpVideoStreamReceiver2::RtcpFeedbackBuffer::SendBufferedRtcpFeedback() {
   }
 }
 
+void RtpVideoStreamReceiver2::RtcpFeedbackBuffer::ClearLossNotificationState() {
+  RTC_DCHECK_RUN_ON(&packet_sequence_checker_);
+  lntf_state_.reset();
+}
+
 RtpVideoStreamReceiver2::RtpVideoStreamReceiver2(
     TaskQueueBase* current_queue,
     Clock* clock,
@@ -935,6 +940,18 @@ void RtpVideoStreamReceiver2::SetPacketSink(
   packet_sink_ = packet_sink;
 }
 
+void RtpVideoStreamReceiver2::SetLossNotificationEnabled(bool enabled) {
+  RTC_DCHECK_RUN_ON(&packet_sequence_checker_);
+  if (enabled && !loss_notification_controller_) {
+    loss_notification_controller_ =
+        std::make_unique<LossNotificationController>(&rtcp_feedback_buffer_,
+                                                     &rtcp_feedback_buffer_);
+  } else if (!enabled && loss_notification_controller_) {
+    loss_notification_controller_.reset();
+    rtcp_feedback_buffer_.ClearLossNotificationState();
+  }
+}
+
 absl::optional<int64_t> RtpVideoStreamReceiver2::LastReceivedPacketMs() const {
   RTC_DCHECK_RUN_ON(&packet_sequence_checker_);
   if (last_received_rtp_system_time_) {

video/rtp_video_stream_receiver2.h

@@ -194,6 +194,10 @@ class RtpVideoStreamReceiver2 : public LossNotificationSender,
   // thread` but will be `network thread`.
   void SetPacketSink(RtpPacketSinkInterface* packet_sink);
 
+  // Turns on/off loss notifications. Must be called on the packet delivery
+  // thread.
+  void SetLossNotificationEnabled(bool enabled);
+
   absl::optional<int64_t> LastReceivedPacketMs() const;
   absl::optional<int64_t> LastReceivedKeyframePacketMs() const;
 
@@ -236,6 +240,8 @@ class RtpVideoStreamReceiver2 : public LossNotificationSender,
     // Send all RTCP feedback messages buffered thus far.
     void SendBufferedRtcpFeedback();
 
+    void ClearLossNotificationState();
+
    private:
     // LNTF-related state.
     struct LossNotificationState {
@@ -336,7 +342,8 @@ class RtpVideoStreamReceiver2 : public LossNotificationSender,
 
   RtcpFeedbackBuffer rtcp_feedback_buffer_;
   const std::unique_ptr<NackRequester> nack_module_;
-  std::unique_ptr<LossNotificationController> loss_notification_controller_;
+  std::unique_ptr<LossNotificationController> loss_notification_controller_
+      RTC_GUARDED_BY(packet_sequence_checker_);
 
   video_coding::PacketBuffer packet_buffer_
       RTC_GUARDED_BY(packet_sequence_checker_);

video/video_receive_stream2.cc

@@ -517,6 +517,13 @@ void VideoReceiveStream2::SetFlexFecProtection(
       (flexfec_sink != nullptr);
 }
 
+void VideoReceiveStream2::SetLossNotificationEnabled(bool enabled) {
+  RTC_DCHECK_RUN_ON(&packet_sequence_checker_);
+  // TODO(tommi): Stop using the config struct for the internal state.
+  const_cast<bool&>(config_.rtp.lntf.enabled) = enabled;
+  rtp_video_stream_receiver_.SetLossNotificationEnabled(enabled);
+}
+
 void VideoReceiveStream2::CreateAndRegisterExternalDecoder(
     const Decoder& decoder) {
   TRACE_EVENT0("webrtc",

video/video_receive_stream2.h

@@ -147,6 +147,7 @@ class VideoReceiveStream2
   void SetTransportCc(bool transport_cc) override;
   void SetRtcpMode(RtcpMode mode) override;
   void SetFlexFecProtection(RtpPacketSinkInterface* flexfec_sink) override;
+  void SetLossNotificationEnabled(bool enabled) override;
 
   webrtc::VideoReceiveStreamInterface::Stats GetStats() const override;