From 6e07514c4460c378b8909c25616e3694e33c1905 Mon Sep 17 00:00:00 2001
From: Pierre HUBERT <pierre.git@communiquons.org>
Date: Sun, 3 May 2020 20:57:52 +0200
Subject: [PATCH] Better wait for new tracks

---
 relay.go | 37 ++++++++++++++++++++++++-------------
 1 file changed, 24 insertions(+), 13 deletions(-)

diff --git a/relay.go b/relay.go
index 7457b69..1816fd7 100644
--- a/relay.go
+++ b/relay.go
@@ -8,6 +8,7 @@ import (
 	"encoding/json"
 	"io"
 	"log"
+	"strings"
 	"sync"
 	"time"
 
@@ -192,7 +193,16 @@ func processCloseRequests() {
 /// Start new call
 func newCall(mainOffer receivedSignal, r *activeRelay) {
 
-	log.Printf("Starting new call: %s / id: %d", r.callHash, r.id)
+	// I am not sure this is a strong way to determine whether we are having
+	// a video call or not, but I have not found any better way yet...
+	isVideoCall := strings.Contains(mainOffer.sdp.SDP, "m=video") || strings.Contains(mainOffer.sdp.SDP, "mid:video")
+	print(mainOffer.sdp.SDP)
+	numberTracks := 1
+	if isVideoCall {
+		numberTracks = 2
+	}
+
+	log.Printf("Starting new call: %s / id: %d / number of tracks: %d", r.callHash, r.id, numberTracks)
 
 	// Ice candidates mutex
 	var candidatesMux sync.Mutex
@@ -279,7 +289,7 @@ func newCall(mainOffer receivedSignal, r *activeRelay) {
 		return
 	}
 
-	localTrackChan := make(chan *webrtc.Track)
+	localTrackChan := make(chan *webrtc.Track, numberTracks)
 
 	// Set a handler for when a new remote track starts, this just distributes all our packets
 	// to connected peers
@@ -400,17 +410,6 @@ func newCall(mainOffer receivedSignal, r *activeRelay) {
 	// Enter messags loop
 	for {
 
-		// Receive new channels
-		stopCheck := len(localTracks) >= 2 // Stop check if we got all the channel
-		for !stopCheck {
-			select {
-			case t := <-localTrackChan:
-				localTracks = append(localTracks, t)
-			case <-time.After(time.Millisecond * 100):
-				stopCheck = true
-			}
-		}
-
 		newMessage, ok := <-r.channel
 
 		if !ok {
@@ -426,6 +425,18 @@ func newCall(mainOffer receivedSignal, r *activeRelay) {
 				val.Close()
 			}
 
+			// First, we must make sure that we got all the tracks we need, before
+			// creating an offer (in order not to miss a track while building the offer)
+			stopCheck := len(localTracks) >= numberTracks // Stop check if we got all the channel
+			for !stopCheck {
+				select {
+				case t := <-localTrackChan:
+					localTracks = append(localTracks, t)
+				case <-time.After(time.Millisecond * 1000):
+					stopCheck = true
+				}
+			}
+
 			// Ice candidates mutex
 			var newCandidatesMux sync.Mutex
 			newPendingCandidates := make([]*webrtc.ICECandidate, 0)