Add examples of using pion-WebRTC with Janus

This adds an example of how to use pion-WebRTC with the streaming
plugin. This isn't production ready until #175 is resolved, but is
enough to start adding rough code/debugging around.

Resolves #74

Co-authored-by: Sean DuBois <sean@siobud.com>

janus-gateway/streaming/main.go

@@ -0,0 +1,125 @@
+package main
+
+import (
+	"fmt"
+
+	janus "github.com/notedit/janus-go"
+	"github.com/pions/webrtc"
+	"github.com/pions/webrtc/pkg/ice"
+	"github.com/pions/webrtc/pkg/media/ivfwriter"
+)
+
+func watchHandle(handle *janus.Handle) {
+	// wait for event
+	for {
+		msg := <-handle.Events
+		switch msg := msg.(type) {
+		case *janus.SlowLinkMsg:
+			fmt.Print("SlowLinkMsg type ", handle.Id)
+		case *janus.MediaMsg:
+			fmt.Print("MediaEvent type", msg.Type, " receiving ", msg.Receiving)
+		case *janus.WebRTCUpMsg:
+			fmt.Print("WebRTCUp type ", handle.Id)
+		case *janus.HangupMsg:
+			fmt.Print("HangupEvent type ", handle.Id)
+		case *janus.EventMsg:
+			fmt.Printf("EventMsg %+v", msg.Plugindata.Data)
+		}
+
+	}
+
+}
+
+func main() {
+	webrtc.RegisterDefaultCodecs()
+
+	// Create a new RTCPeerConnection
+	peerConnection, err := webrtc.New(webrtc.RTCConfiguration{})
+	if err != nil {
+		panic(err)
+	}
+
+	peerConnection.OnICEConnectionStateChange = func(connectionState ice.ConnectionState) {
+		fmt.Printf("Connection State has changed %s \n", connectionState.String())
+	}
+
+	peerConnection.OnTrack = func(track *webrtc.RTCTrack) {
+		if track.Codec.Name == webrtc.Opus {
+			return
+		}
+
+		fmt.Println("Got VP8 track, saving to disk as output.ivf")
+		i, err := ivfwriter.New("output.ivf")
+		if err != nil {
+			panic(err)
+		}
+		for {
+			if err := i.AddPacket(<-track.Packets); err != nil {
+				panic(err)
+			}
+		}
+	}
+
+	// Janus
+	gateway, err := janus.Connect("ws://localhost:8188/")
+
+	if err != nil {
+		panic(err)
+	}
+
+	// Create session
+	session, err := gateway.Create()
+
+	if err != nil {
+		panic(err)
+	}
+
+	// Create handle
+	handle, err := session.Attach("janus.plugin.streaming")
+
+	go watchHandle(handle)
+
+	// Get streaming list
+	if _, err := handle.Request(map[string]interface{}{
+		"request": "list",
+	}); err != nil {
+		panic(err)
+	}
+
+	// Watch the second stream
+	msg, err := handle.Message(map[string]interface{}{
+		"request": "watch",
+		"id":      1,
+	}, nil)
+
+	if err != nil {
+		fmt.Print("message", msg)
+		panic(err)
+	}
+
+	if msg.Jsep != nil {
+		if err := peerConnection.SetRemoteDescription(webrtc.RTCSessionDescription{
+			Type: webrtc.RTCSdpTypeOffer,
+			Sdp:  msg.Jsep["sdp"].(string),
+		}); err != nil {
+			panic(err)
+		}
+
+		answer, err := peerConnection.CreateAnswer(nil)
+		if err != nil {
+			panic(err)
+		}
+
+		// now we start
+		if _, err := handle.Message(map[string]interface{}{
+			"request": "start",
+		}, map[string]interface{}{
+			"type":    "answer",
+			"sdp":     answer.Sdp,
+			"trickle": false,
+		}); err != nil {
+			panic(err)
+		}
+	}
+	select {}
+}