Ignore receiver reports that have a sequence number before first packet. (#1745)

pkg/sfu/buffer/rtpstats.go

@@ -539,7 +539,9 @@ func (r *RTPStats) UpdateFromReceiverReport(rr rtcp.ReceptionReport) (rtt uint32
 	r.lock.Lock()
 	defer r.lock.Unlock()
 
-	if !r.endTime.IsZero() || !r.params.IsReceiverReportDriven {
+	if !r.endTime.IsZero() || !r.params.IsReceiverReportDriven || rr.LastSequenceNumber < r.extStartSN {
+		// it is possible that the `LastSequenceNumber` in the receiver report is before the starting
+		// sequence number when dummy packets are used to trigger Pion's OnTrack path.
 		return
 	}
 
@@ -1107,7 +1109,7 @@ func (r *RTPStats) DeltaInfoOverridden(snapshotId uint32) *RTPDeltaInfo {
 	packetsExpected := now.extStartSNOverridden - then.extStartSNOverridden
 	if packetsExpected > NumSequenceNumbers {
 		r.logger.Warnw(
-			"too many packets expected in delta",
+			"too many packets expected in delta (overridden)",
 			fmt.Errorf("start: %d, end: %d, expected: %d", then.extStartSNOverridden, now.extStartSNOverridden, packetsExpected),
 		)
 		return nil
@@ -1558,7 +1560,7 @@ func (r *RTPStats) updateGapHistogram(gap int) {
 }
 
 func (r *RTPStats) getAndResetSnapshot(snapshotId uint32, override bool) (*Snapshot, *Snapshot) {
-	if !r.initialized || (r.params.IsReceiverReportDriven && r.lastRRTime.IsZero()) {
+	if !r.initialized || (override && r.lastRRTime.IsZero()) {
 		return nil, nil
 	}
 
@@ -1573,7 +1575,7 @@ func (r *RTPStats) getAndResetSnapshot(snapshotId uint32, override bool) (*Snaps
 	}
 
 	var startTime time.Time
-	if override && r.params.IsReceiverReportDriven {
+	if override {
 		startTime = r.lastRRTime
 	} else {
 		startTime = time.Now()

pkg/sfu/downtrack.go

@@ -652,7 +652,7 @@ func (d *DownTrack) WriteRTP(extPkt *buffer.ExtPacket, layer int32) error {
 
 // WritePaddingRTP tries to write as many padding only RTP packets as necessary
 // to satisfy given size to the DownTrack
-func (d *DownTrack) WritePaddingRTP(bytesToSend int, paddingOnMute bool) int {
+func (d *DownTrack) WritePaddingRTP(bytesToSend int, paddingOnMute bool, forceMarker bool) int {
 	if !d.rtpStats.IsActive() && !paddingOnMute {
 		return 0
 	}
@@ -684,7 +684,7 @@ func (d *DownTrack) WritePaddingRTP(bytesToSend int, paddingOnMute bool) int {
 		return 0
 	}
 
-	snts, err := d.forwarder.GetSnTsForPadding(num)
+	snts, err := d.forwarder.GetSnTsForPadding(num, forceMarker)
 	if err != nil {
 		return 0
 	}
@@ -1699,10 +1699,10 @@ func (d *DownTrack) onBindAndConnected() {
 }
 
 func (d *DownTrack) sendPaddingOnMute() {
-	d.logger.Debugw("sending padding on mute")
 	// let uptrack have chance to send packet before we send padding
 	time.Sleep(waitBeforeSendPaddingOnMute)
 
+	d.logger.Debugw("sending padding on mute")
 	if d.kind == webrtc.RTPCodecTypeVideo {
 		d.sendPaddingOnMuteForVideo()
 	} else if d.mime == "audio/opus" {
@@ -1717,7 +1717,7 @@ func (d *DownTrack) sendPaddingOnMuteForVideo() {
 		if d.rtpStats.IsActive() || d.IsClosed() {
 			return
 		}
-		d.WritePaddingRTP(20, true)
+		d.WritePaddingRTP(20, true, true)
 		time.Sleep(paddingOnMuteInterval)
 	}
 }

pkg/sfu/forwarder.go

@@ -1649,7 +1649,7 @@ func (f *Forwarder) maybeStart() {
 	f.firstTS = extPkt.Packet.Timestamp
 }
 
-func (f *Forwarder) GetSnTsForPadding(num int) ([]SnTs, error) {
+func (f *Forwarder) GetSnTsForPadding(num int, forceMarker bool) ([]SnTs, error) {
 	f.lock.Lock()
 	defer f.lock.Unlock()
 
@@ -1660,7 +1660,6 @@ func (f *Forwarder) GetSnTsForPadding(num int) ([]SnTs, error) {
 	// not get out-of-sync. But, when a stream is paused,
 	// force a frame marker as a restart of the stream will
 	// start with a key frame which will reset the decoder.
-	forceMarker := false
 	if !f.vls.GetTarget().IsValid() {
 		forceMarker = true
 	}

pkg/sfu/forwarder_test.go

@@ -1770,7 +1770,7 @@ func TestForwardGetSnTsForPadding(t *testing.T) {
 	disable(f)
 
 	// should get back frame end needed as the last packet did not have RTP marker set
-	snts, err := f.GetSnTsForPadding(5)
+	snts, err := f.GetSnTsForPadding(5, false)
 	require.NoError(t, err)
 
 	numPadding := 5
@@ -1786,7 +1786,7 @@ func TestForwardGetSnTsForPadding(t *testing.T) {
 	require.Equal(t, sntsExpected, snts)
 
 	// now that there is a marker, timestamp should jump on first padding when asked again
-	snts, err = f.GetSnTsForPadding(numPadding)
+	snts, err = f.GetSnTsForPadding(numPadding, false)
 	require.NoError(t, err)
 
 	for i := 0; i < numPadding; i++ {

pkg/sfu/streamallocator/track.go

@@ -135,7 +135,7 @@ func (t *Track) SetMaxLayer(layer buffer.VideoLayer) bool {
 }
 
 func (t *Track) WritePaddingRTP(bytesToSend int) int {
-	return t.downTrack.WritePaddingRTP(bytesToSend, false)
+	return t.downTrack.WritePaddingRTP(bytesToSend, false, false)
 }
 
 func (t *Track) AllocateOptimal(allowOvershoot bool) sfu.VideoAllocation {