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

examples/broadcast/README.md

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+# broadcast
+broadcast is a Pion WebRTC application that demonstrates how to broadcast a video to many peers, while only requiring the broadcaster to upload once.
+
+This could serve as the building block to building conferencing software, and other applications where publishers are bandwidth constrained.
+
+## Instructions
+### Download broadcast
+```
+go install github.com/pion/webrtc/v4/examples/broadcast@latest
+```
+
+### Open broadcast example page
+[jsfiddle.net](https://jsfiddle.net/us4h58jx/) You should see two buttons `Publish a Broadcast` and `Join a Broadcast`
+
+### Run Broadcast
+#### Linux/macOS
+Run `broadcast` OR run `main.go` in `github.com/pion/webrtc/examples/broadcast`
+
+### Start a publisher
+
+* Click `Publish a Broadcast`
+* Press `Copy browser SDP to clipboard` or copy the `Browser base64 Session Description` string manually
+* Run `curl localhost:8080 -d "$BROWSER_OFFER"`. `$BROWSER_OFFER` is the value you copied in the last step.
+* The `broadcast` terminal application will respond with an answer, paste this into the second input field in your browser.
+* Press `Start Session`
+* The connection state will be printed in the terminal and under `logs` in the browser.
+
+### Join the broadcast
+* Click `Join a Broadcast`
+* Copy the string in the first input labelled `Browser base64 Session Description`
+* Run `curl localhost:8080 -d "$BROWSER_OFFER"`. `$BROWSER_OFFER` is the value you copied in the last step.
+* The `broadcast` terminal application will respond with an answer, paste this into the second input field in your browser.
+* Press `Start Session`
+* The connection state will be printed in the terminal and under `logs` in the browser.
+
+You can change the listening port using `-port 8011`
+
+You can `Join the broadcast` as many times as you want. The `broadcast` Golang application is relaying all traffic, so your browser only has to upload once.
+
+Congrats, you have used Pion WebRTC! Now start building something cool

examples/broadcast/jsfiddle/demo.css

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+/*
+    SPDX-FileCopyrightText: 2026 The Pion community <https://pion.ly>
+    SPDX-License-Identifier: MIT
+*/
+textarea {
+    width: 500px;
+    min-height: 75px;
+}

examples/broadcast/jsfiddle/demo.details

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+---
+# SPDX-FileCopyrightText: 2026 The Pion community <https://pion.ly>
+# SPDX-License-Identifier: MIT
+
+name: broadcast
+description: Example of a broadcast using Pion WebRTC
+authors:
+  - Sean DuBois

examples/broadcast/jsfiddle/demo.html

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+<!--
+	SPDX-FileCopyrightText: 2026 The Pion community <https://pion.ly>
+	SPDX-License-Identifier: MIT
+-->
+<div id="signalingContainer" style="display: none">
+  Browser base64 Session Description<br />
+  <textarea id="localSessionDescription" readonly="true"></textarea> <br />
+  <button onclick="window.copySDP()">
+    Copy browser SDP to clipboard
+  </button>
+  <br />
+  <br />
+
+  Golang base64 Session Description<br />
+  <textarea id="remoteSessionDescription"></textarea> <br/>
+  <button onclick="window.startSession()"> Start Session </button><br />
+</div>
+
+<br />
+
+Video<br />
+<video id="video1" width="160" height="120" autoplay muted></video> <br />
+
+<button class="createSessionButton" onclick="window.createSession(true)"> Publish a Broadcast </button>
+<button class="createSessionButton" onclick="window.createSession(false)"> Join a Broadcast </button><br />
+
+<br />
+
+Logs<br />
+<div id="logs"></div>

examples/broadcast/jsfiddle/demo.js

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+/* eslint-env browser */
+
+// SPDX-FileCopyrightText: 2026 The Pion community <https://pion.ly>
+// SPDX-License-Identifier: MIT
+
+const log = msg => {
+  document.getElementById('logs').innerHTML += msg + '<br>'
+}
+
+window.createSession = isPublisher => {
+  const pc = new RTCPeerConnection({
+    iceServers: [
+      {
+        urls: 'stun:stun.l.google.com:19302'
+      }
+    ]
+  })
+  pc.oniceconnectionstatechange = e => log(pc.iceConnectionState)
+  pc.onicecandidate = event => {
+    if (event.candidate === null) {
+      document.getElementById('localSessionDescription').value = btoa(JSON.stringify(pc.localDescription))
+    }
+  }
+
+  if (isPublisher) {
+    navigator.mediaDevices.getUserMedia({ video: true, audio: false })
+      .then(stream => {
+        stream.getTracks().forEach(track => pc.addTrack(track, stream))
+        document.getElementById('video1').srcObject = stream
+        pc.createOffer()
+          .then(d => pc.setLocalDescription(d))
+          .catch(log)
+      }).catch(log)
+  } else {
+    pc.addTransceiver('video')
+    pc.createOffer()
+      .then(d => pc.setLocalDescription(d))
+      .catch(log)
+
+    pc.ontrack = function (event) {
+      const el = document.getElementById('video1')
+      el.srcObject = event.streams[0]
+      el.autoplay = true
+      el.controls = true
+    }
+  }
+
+  window.startSession = () => {
+    const sd = document.getElementById('remoteSessionDescription').value
+    if (sd === '') {
+      return alert('Session Description must not be empty')
+    }
+
+    try {
+      pc.setRemoteDescription(JSON.parse(atob(sd)))
+    } catch (e) {
+      alert(e)
+    }
+  }
+
+  window.copySDP = () => {
+    const browserSDP = document.getElementById('localSessionDescription')
+
+    browserSDP.focus()
+    browserSDP.select()
+
+    try {
+      const successful = document.execCommand('copy')
+      const msg = successful ? 'successful' : 'unsuccessful'
+      log('Copying SDP was ' + msg)
+    } catch (err) {
+      log('Unable to copy SDP ' + err)
+    }
+  }
+
+  const btns = document.getElementsByClassName('createSessionButton')
+  for (let i = 0; i < btns.length; i++) {
+    btns[i].style = 'display: none'
+  }
+
+  document.getElementById('signalingContainer').style = 'display: block'
+}

examples/broadcast/main.go

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+// 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
+}