From d56628be158ecfb237e4c0510720aa1c06c6c9f1 Mon Sep 17 00:00:00 2001
From: Juliusz Chroboczek <jch@irif.fr>
Date: Thu, 21 May 2020 01:14:54 +0200
Subject: [PATCH] Send FIR when WriteRTP returns ErrKeyframeNeeded.

---
 client.go | 23 ++++++++++++++++++++++-
 conn.go   |  2 ++
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/client.go b/client.go
index ff9a0cf..5674e2a 100644
--- a/client.go
+++ b/client.go
@@ -471,11 +471,14 @@ func writeLoop(conn *upConnection, track *upTrack, ch <-chan packetIndex) {
 
 	local := make([]downTrack, 0)
 
+	firSent := false
+
 	for {
 		select {
 		case action := <-track.localCh:
 			if action.add {
 				local = append(local, action.track)
+				firSent = false
 			} else {
 				found := false
 				for i, t := range local {
@@ -505,16 +508,34 @@ func writeLoop(conn *upConnection, track *upTrack, ch <-chan packetIndex) {
 				continue
 			}
 
+			kfNeeded := false
+
 			for _, l := range local {
 				err := l.WriteRTP(&packet)
 				if err != nil {
-					if err != io.ErrClosedPipe {
+					if err == ErrKeyframeNeeded {
+						kfNeeded = true
+					} else if err != io.ErrClosedPipe {
 						log.Printf("WriteRTP: %v", err)
 					}
 					continue
 				}
 				l.Accumulate(uint32(bytes))
 			}
+
+			if kfNeeded {
+				err := conn.sendFIR(track, !firSent)
+				if err == ErrUnsupportedFeedback {
+					err := conn.sendPLI(track)
+					if err != nil &&
+						err != ErrUnsupportedFeedback {
+						log.Printf("sendPLI: %v", err)
+					}
+				} else if err != nil {
+					log.Printf("sendFIR: %v", err)
+				}
+				firSent = true
+			}
 		}
 	}
 }
diff --git a/conn.go b/conn.go
index 01803f0..89a15ed 100644
--- a/conn.go
+++ b/conn.go
@@ -241,6 +241,8 @@ func (s *receiverStats) Get(now uint64) (uint8, uint32) {
 	return uint8(atomic.LoadUint32(&s.loss)), atomic.LoadUint32(&s.jitter)
 }
 
+var ErrKeyframeNeeded = errors.New("keyframe needed")
+
 type downTrack interface {
 	WriteRTP(packat *rtp.Packet) error
 	Accumulate(bytes uint32)