Use new intervalpli interceptor in examples

Instead of manually spawning a goroutine this demonstrates how an
interceptor can be useful.

Co-authored-by: Antoine Baché <antoine@tenten.app>

examples/reflect/main.go

@@ -7,10 +7,9 @@ package main
 import (
 	"fmt"
 	"os"
-	"time"
 
 	"github.com/pion/interceptor"
-	"github.com/pion/rtcp"
+	"github.com/pion/interceptor/pkg/intervalpli"
 	"github.com/pion/webrtc/v3"
 	"github.com/pion/webrtc/v3/examples/internal/signal"
 )
@@ -42,6 +41,16 @@ func main() {
 		panic(err)
 	}
 
+	// Register a intervalpli factory
+	// This interceptor sends a PLI every 3 seconds. A PLI causes a video keyframe to be generated by the sender.
+	// This makes our video seekable and more error resilent, but at a cost of lower picture quality and higher bitrates
+	// A real world application should process incoming RTCP packets from viewers and forward them to senders
+	intervalPliFactory, err := intervalpli.NewReceiverInterceptor()
+	if err != nil {
+		panic(err)
+	}
+	i.Add(intervalPliFactory)
+
 	// Create the API object with the MediaEngine
 	api := webrtc.NewAPI(webrtc.WithMediaEngine(m), webrtc.WithInterceptorRegistry(i))
 
@@ -101,18 +110,6 @@ func main() {
 	// Set a handler for when a new remote track starts, this handler copies inbound RTP packets,
 	// replaces the SSRC and sends them back
 	peerConnection.OnTrack(func(track *webrtc.TrackRemote, receiver *webrtc.RTPReceiver) {
-		// Send a PLI on an interval so that the publisher is pushing a keyframe every rtcpPLIInterval
-		// This is a temporary fix until we implement incoming RTCP events, then we would push a PLI only when a viewer requests it
-		go func() {
-			ticker := time.NewTicker(time.Second * 3)
-			for range ticker.C {
-				errSend := peerConnection.WriteRTCP([]rtcp.Packet{&rtcp.PictureLossIndication{MediaSSRC: uint32(track.SSRC())}})
-				if errSend != nil {
-					fmt.Println(errSend)
-				}
-			}
-		}()
-
 		fmt.Printf("Track has started, of type %d: %s \n", track.PayloadType(), track.Codec().MimeType)
 		for {
 			// Read RTP packets being sent to Pion