From c6ab41dc8c9816a2a457f61b5d90d2436dfbb471 Mon Sep 17 00:00:00 2001
From: dakkar <dakkar@thenautilus.net>
Date: Sat, 25 Jul 2020 11:31:23 +0000
Subject: changes from another guy

https://github.com/ahamlinman/rtwatch/commit/eb91a43eeccc5959ea981dbc6eef10978d5179fb
---
 gst/gst.go | 24 +++++++++++++++++++++++-
 index.html | 45 ++++++++++++++++++++++----------------------
 main.go    | 63 ++++++++++++++++++++++++++++++++++++--------------------------
 3 files changed, 83 insertions(+), 49 deletions(-)

diff --git a/gst/gst.go b/gst/gst.go
index f8a5385..7282aab 100644
--- a/gst/gst.go
+++ b/gst/gst.go
@@ -31,9 +31,31 @@ type Pipeline struct {
 var pipeline = &Pipeline{}
 var pipelinesLock sync.Mutex
 
+var pipelineFmtStr = `
+filesrc location="%s"
+! decodebin name=demux
+
+demux.
+! queue
+! videoconvert
+! videoscale
+! video/x-raw,width=800,height=600
+! x264enc bframes=0 speed-preset=veryfast key-int-max=60
+! video/x-h264,stream-format=byte-stream
+! appsink name=video
+
+demux.
+! queue
+! audioconvert
+! audioresample
+! audio/x-raw,rate=48000
+! opusenc bitrate=128000
+! appsink name=audio
+`
+
 // CreatePipeline creates a GStreamer Pipeline
 func CreatePipeline(containerPath string, audioTrack, videoTrack *webrtc.Track) *Pipeline {
-	pipelineStr := fmt.Sprintf("filesrc location=\"%s\" ! decodebin name=demux ! queue ! x264enc bframes=0 speed-preset=veryfast key-int-max=60 ! video/x-h264,stream-format=byte-stream ! appsink name=video demux. ! queue ! audioconvert ! audioresample ! opusenc ! appsink name=audio", containerPath)
+	pipelineStr := fmt.Sprintf(pipelineFmtStr, containerPath)
 
 	pipelineStrUnsafe := C.CString(pipelineStr)
 	defer C.free(unsafe.Pointer(pipelineStrUnsafe))
diff --git a/index.html b/index.html
index fc641bf..9f88bb2 100644
--- a/index.html
+++ b/index.html
@@ -15,8 +15,10 @@
     </div>
 
     <script>
-     let conn = new WebSocket('wss://' + window.location.host + window.location.pathname + '/ws/')
+
      let pc = new RTCPeerConnection()
+     pc.addTransceiver('video', {direction: 'recvonly'});
+     pc.addTransceiver('audio', {direction: 'recvonly'});
 
      window.seekClick = () => {
        conn.send(JSON.stringify({event: 'seek', data: document.getElementById('seekTime').value}))
@@ -30,26 +32,19 @@
 
      pc.ontrack = function (event) {
        if (event.track.kind === 'audio') {
-         //return
+         return
        }
        var el = document.getElementById('video1')
-       el.srcObject = event.streams[0]
-       el.autoplay = true
-       el.controls = true
+       el.srcObject = event.streams[0];
+       el.autoplay = true;
+       el.controls = true;
      }
 
-     conn.onopen = () => {
-       navigator.mediaDevices.getUserMedia({video: true, audio: true}).then(g => {
-         for (const track of g.getTracks()) {
-           pc.addTrack(track,g);
-         }
+     let conn = new WebSocket('wss://' + window.location.host + window.location.pathname + '/ws/')
+     window.conn = conn
 
-         pc.createOffer({offerToReceiveVideo: true, offerToReceiveAudio: true}).then(offer => {
-           return pc.setLocalDescription(offer);
-	   }).then(() => {
-           conn.send(JSON.stringify({event: 'offer', data: JSON.stringify(pc.localDescription)}))
-         })
-       }).catch(e => { console.log(`failed getUserMedia: ${e}`) });
+     conn.onopen = () => {
+       console.log('Connection opened')
      }
 
      conn.onclose = evt => {
@@ -63,15 +58,21 @@
        }
 
        switch (msg.event) {
-         case 'answer':
-           answer = JSON.parse(msg.data)
-           if (!answer) {
-             return console.log('failed to parse answer')
+         case 'offer':
+           offer = JSON.parse(msg.data)
+           if (!offer) {
+             return console.log('failed to parse offer')
            }
-           pc.setRemoteDescription(answer)
+           console.log('Received offer', offer);
+	   (async () => {
+	     pc.setRemoteDescription(offer);
+	     const answer = await pc.createAnswer();
+	     await pc.setLocalDescription(answer);
+	     console.log('Sending answer', answer);
+	     conn.send(JSON.stringify({event: 'answer', data: JSON.stringify(answer)}));
+	   })();
        }
      }
-     window.conn = conn
     </script>
   </body>
 </html>
diff --git a/main.go b/main.go
index 42c8fbf..1b862b6 100644
--- a/main.go
+++ b/main.go
@@ -45,6 +45,7 @@ func main() {
 		panic("-container-path must be specified")
 	}
 
+	log.Println("Initializing WebRTC PeerConnection")
 	pc, err := webrtc.NewPeerConnection(webrtc.Configuration{
 		ICEServers: []webrtc.ICEServer{
 			{
@@ -56,16 +57,18 @@ func main() {
 		log.Fatal(err)
 	}
 
-	videoTrack, err = pc.NewTrack(webrtc.DefaultPayloadTypeH264, 5000, "synced-video", "synced-video")
+	log.Println("Initializing WebRTC tracks")
+	videoTrack, err = pc.NewTrack(webrtc.DefaultPayloadTypeH264, 5000, "sync", "sync")
 	if err != nil {
 		log.Fatal(err)
 	}
 
-	audioTrack, err = pc.NewTrack(webrtc.DefaultPayloadTypeOpus, 5001, "synced-video", "synced-video")
+	audioTrack, err = pc.NewTrack(webrtc.DefaultPayloadTypeOpus, 5001, "sync", "sync")
 	if err != nil {
 		log.Fatal(err)
 	}
 
+	log.Println("Creating and starting pipeline")
 	pipeline = gst.CreatePipeline(containerPath, audioTrack, videoTrack)
 	pipeline.Start()
 
@@ -87,33 +90,13 @@ func handleWebsocketMessage(pc *webrtc.PeerConnection, ws *websocket.Conn, messa
 			log.Print(err)
 		}
 		pipeline.SeekToTime(i)
-	case "offer":
-		offer := webrtc.SessionDescription{}
-		if err := json.Unmarshal([]byte(message.Data), &offer); err != nil {
+	case "answer":
+		answer := webrtc.SessionDescription{}
+		if err := json.Unmarshal([]byte(message.Data), &answer); err != nil {
 			return err
 		}
 
-		if err := pc.SetRemoteDescription(offer); err != nil {
-			return err
-		}
-
-		answer, err := pc.CreateAnswer(nil)
-		if err != nil {
-			return err
-		}
-		if err := pc.SetLocalDescription(answer); err != nil {
-			return err
-		}
-
-		answerString, err := json.Marshal(answer)
-		if err != nil {
-			return err
-		}
-
-		if err = ws.WriteJSON(&websocketMessage{
-			Event: "answer",
-			Data:  string(answerString),
-		}); err != nil {
+		if err := pc.SetRemoteDescription(answer); err != nil {
 			return err
 		}
 	}
@@ -133,6 +116,8 @@ func serveWs(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	defer ws.Close()
+
 	peerConnection, err := webrtc.NewPeerConnection(peerConnectionConfig)
 	if err != nil {
 		log.Print(err)
@@ -151,6 +136,32 @@ func serveWs(w http.ResponseWriter, r *http.Request) {
 		}
 	}()
 
+	sdp, err := peerConnection.CreateOffer(nil)
+	if err != nil {
+		log.Println(err)
+		return
+	}
+
+	if err := peerConnection.SetLocalDescription(sdp); err != nil {
+		log.Println(err)
+		return
+	}
+
+	sdpData, err := json.Marshal(sdp)
+	if err != nil {
+		log.Print(err)
+		return
+	}
+
+	offerMsg := &websocketMessage{
+		Event: "offer",
+		Data:  string(sdpData),
+	}
+	if err := ws.WriteJSON(offerMsg); err != nil {
+		log.Print(err)
+		return
+	}
+
 	message := &websocketMessage{}
 	for {
 		_, msg, err := ws.ReadMessage()
-- 
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