snapshot of https://github.com/pion/webrtc.git (main, 2026-09-15; blobs > 131072B omitted)

examples/broadcast/main.go

@@ -0,0 +1,242 @@
+// SPDX-FileCopyrightText: 2026 The Pion community <https://pion.ly>
+// SPDX-License-Identifier: MIT
+
+//go:build !js
+
+// broadcast demonstrates how to broadcast a video to many peers, while only requiring the broadcaster to upload once.
+package main
+
+import (
+	"encoding/base64"
+	"encoding/json"
+	"errors"
+	"flag"
+	"fmt"
+	"io"
+	"net/http"
+	"strconv"
+
+	"github.com/pion/interceptor"
+	"github.com/pion/interceptor/pkg/intervalpli"
+	"github.com/pion/webrtc/v4"
+)
+
+// nolint:gocognit, cyclop
+func main() {
+	port := flag.Int("port", 8080, "http server port")
+	flag.Parse()
+
+	sdpChan := httpSDPServer(*port)
+
+	// Everything below is the Pion WebRTC API, thanks for using it ❤️.
+	offer := webrtc.SessionDescription{}
+	decode(<-sdpChan, &offer)
+	fmt.Println("")
+
+	peerConnectionConfig := webrtc.Configuration{
+		ICEServers: []webrtc.ICEServer{
+			{
+				URLs: []string{"stun:stun.l.google.com:19302"},
+			},
+		},
+	}
+
+	mediaEngine := &webrtc.MediaEngine{}
+	if err := mediaEngine.RegisterDefaultCodecs(); err != nil {
+		panic(err)
+	}
+
+	// Create a InterceptorRegistry. This is the user configurable RTP/RTCP Pipeline.
+	// This provides NACKs, RTCP Reports and other features. If you use `webrtc.NewPeerConnection`
+	// this is enabled by default. If you are manually managing You MUST create a InterceptorRegistry
+	// for each PeerConnection.
+	interceptorRegistry := &interceptor.Registry{}
+
+	// Use the default set of Interceptors
+	if err := webrtc.RegisterDefaultInterceptors(mediaEngine, interceptorRegistry); err != nil {
+		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)
+	}
+	interceptorRegistry.Add(intervalPliFactory)
+
+	// Create a new RTCPeerConnection
+	peerConnection, err := webrtc.NewAPI(
+		webrtc.WithMediaEngine(mediaEngine),
+		webrtc.WithInterceptorRegistry(interceptorRegistry),
+	).NewPeerConnection(peerConnectionConfig)
+	if err != nil {
+		panic(err)
+	}
+	defer func() {
+		if cErr := peerConnection.Close(); cErr != nil {
+			fmt.Printf("cannot close peerConnection: %v\n", cErr)
+		}
+	}()
+
+	// Allow us to receive 1 video track
+	if _, err = peerConnection.AddTransceiverFromKind(webrtc.RTPCodecTypeVideo); err != nil {
+		panic(err)
+	}
+
+	localTrackChan := make(chan *webrtc.TrackLocalStaticRTP)
+	// Set a handler for when a new remote track starts, this just distributes all our packets
+	// to connected peers
+	peerConnection.OnTrack(func(remoteTrack *webrtc.TrackRemote, receiver *webrtc.RTPReceiver) { //nolint: revive
+		// Create a local track, all our SFU clients will be fed via this track
+		localTrack, newTrackErr := webrtc.NewTrackLocalStaticRTP(remoteTrack.Codec().RTPCodecCapability, "video", "pion")
+		if newTrackErr != nil {
+			panic(newTrackErr)
+		}
+		localTrackChan <- localTrack
+
+		rtpBuf := make([]byte, 1400)
+		for {
+			i, _, readErr := remoteTrack.Read(rtpBuf)
+			if readErr != nil {
+				panic(readErr)
+			}
+
+			// ErrClosedPipe means we don't have any subscribers, this is ok if no peers have connected yet
+			if _, err = localTrack.Write(rtpBuf[:i]); err != nil && !errors.Is(err, io.ErrClosedPipe) {
+				panic(err)
+			}
+		}
+	})
+
+	// Set the remote SessionDescription
+	err = peerConnection.SetRemoteDescription(offer)
+	if err != nil {
+		panic(err)
+	}
+
+	// Create answer
+	answer, err := peerConnection.CreateAnswer(nil)
+	if err != nil {
+		panic(err)
+	}
+
+	// Create channel that is blocked until ICE Gathering is complete
+	gatherComplete := webrtc.GatheringCompletePromise(peerConnection)
+
+	// Sets the LocalDescription, and starts our UDP listeners
+	err = peerConnection.SetLocalDescription(answer)
+	if err != nil {
+		panic(err)
+	}
+
+	// Block until ICE Gathering is complete, disabling trickle ICE
+	// we do this because we only can exchange one signaling message
+	// in a production application you should exchange ICE Candidates via OnICECandidate
+	<-gatherComplete
+
+	// Get the LocalDescription and take it to base64 so we can paste in browser
+	fmt.Println(encode(peerConnection.LocalDescription()))
+
+	localTrack := <-localTrackChan
+	for {
+		fmt.Println("")
+		fmt.Println("Curl an base64 SDP to start sendonly peer connection")
+
+		recvOnlyOffer := webrtc.SessionDescription{}
+		decode(<-sdpChan, &recvOnlyOffer)
+
+		// Create a new PeerConnection
+		peerConnection, err := webrtc.NewPeerConnection(peerConnectionConfig)
+		if err != nil {
+			panic(err)
+		}
+
+		rtpSender, err := peerConnection.AddTrack(localTrack)
+		if err != nil {
+			panic(err)
+		}
+
+		// Read incoming RTCP packets
+		// Before these packets are returned they are processed by interceptors. For things
+		// like NACK this needs to be called.
+		go func() {
+			rtcpBuf := make([]byte, 1500)
+			for {
+				if _, _, rtcpErr := rtpSender.Read(rtcpBuf); rtcpErr != nil {
+					return
+				}
+			}
+		}()
+
+		// Set the remote SessionDescription
+		err = peerConnection.SetRemoteDescription(recvOnlyOffer)
+		if err != nil {
+			panic(err)
+		}
+
+		// Create answer
+		answer, err := peerConnection.CreateAnswer(nil)
+		if err != nil {
+			panic(err)
+		}
+
+		// Create channel that is blocked until ICE Gathering is complete
+		gatherComplete = webrtc.GatheringCompletePromise(peerConnection)
+
+		// Sets the LocalDescription, and starts our UDP listeners
+		err = peerConnection.SetLocalDescription(answer)
+		if err != nil {
+			panic(err)
+		}
+
+		// Block until ICE Gathering is complete, disabling trickle ICE
+		// we do this because we only can exchange one signaling message
+		// in a production application you should exchange ICE Candidates via OnICECandidate
+		<-gatherComplete
+
+		// Get the LocalDescription and take it to base64 so we can paste in browser
+		fmt.Println(encode(peerConnection.LocalDescription()))
+	}
+}
+
+// JSON encode + base64 a SessionDescription.
+func encode(obj *webrtc.SessionDescription) string {
+	b, err := json.Marshal(obj)
+	if err != nil {
+		panic(err)
+	}
+
+	return base64.StdEncoding.EncodeToString(b)
+}
+
+// Decode a base64 and unmarshal JSON into a SessionDescription.
+func decode(in string, obj *webrtc.SessionDescription) {
+	b, err := base64.StdEncoding.DecodeString(in)
+	if err != nil {
+		panic(err)
+	}
+
+	if err = json.Unmarshal(b, obj); err != nil {
+		panic(err)
+	}
+}
+
+// httpSDPServer starts a HTTP Server that consumes SDPs.
+func httpSDPServer(port int) chan string {
+	sdpChan := make(chan string)
+	http.HandleFunc("/", func(res http.ResponseWriter, req *http.Request) {
+		body, _ := io.ReadAll(req.Body)
+		fmt.Fprintf(res, "done") //nolint: errcheck
+		sdpChan <- string(body)
+	})
+
+	go func() {
+		// nolint: gosec
+		panic(http.ListenAndServe(":"+strconv.Itoa(port), nil))
+	}()
+
+	return sdpChan
+}