From 26c2f7cd9a1217852a8c61afd827ed7f856800db Mon Sep 17 00:00:00 2001
From: Raja Subramanian <raja.gobi@tutanota.com>
Date: Fri, 3 May 2024 18:56:01 +0530
Subject: [PATCH] Do not use LastTS for dummy offset. (#2700)

* Do not use LastTS for dummy offset.

LastTS could be random when using dummy start. That should not be used
in calculating offsets.

Also, do not push padding into sequence before init. Could have heppened
with dummy start.

* apply dummy offset before comparing to last

* refresh ref TS

* initialize codec munger on catch up forwarding
---
 pkg/sfu/forwarder.go | 13 +++++++++----
 pkg/sfu/sequencer.go |  2 +-
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/pkg/sfu/forwarder.go b/pkg/sfu/forwarder.go
index 6b8415972..9fb66e020 100644
--- a/pkg/sfu/forwarder.go
+++ b/pkg/sfu/forwarder.go
@@ -1589,6 +1589,7 @@ func (f *Forwarder) processSourceSwitch(extPkt *buffer.ExtPacket, layer int32) e
 		return nil
 	} else if f.referenceLayerSpatial == buffer.InvalidLayerSpatial {
 		f.referenceLayerSpatial = layer
+		f.codecMunger.SetLast(extPkt)
 		f.logger.Debugw(
 			"catch up forwarding",
 			"sequenceNumber", extPkt.Packet.SequenceNumber,
@@ -1641,8 +1642,9 @@ func (f *Forwarder) processSourceSwitch(extPkt *buffer.ExtPacket, layer int32) e
 	}
 
 	// adjust extRefTS to current packet's timestamp mapped to that of reference layer's
-	extRefTS = (extRefTS & 0xFFFF_FFFF_0000_0000) + uint64(refTS)
+	extRefTS = (extRefTS & 0xFFFF_FFFF_0000_0000) + uint64(refTS) + f.dummyStartTSOffset
 	lastTS := uint32(extLastTS)
+	refTS = uint32(extRefTS)
 	if (refTS-lastTS) < 1<<31 && refTS < lastTS {
 		extRefTS += (1 << 32)
 	}
@@ -1660,21 +1662,23 @@ func (f *Forwarder) processSourceSwitch(extPkt *buffer.ExtPacket, layer int32) e
 				rtpDiff := uint64(timeSinceFirst.Nanoseconds() * int64(f.codec.ClockRate) / 1e9)
 				extExpectedTS = f.extFirstTS + rtpDiff
 				if f.dummyStartTSOffset == 0 {
-					f.dummyStartTSOffset = extExpectedTS - extRefTS
+					f.dummyStartTSOffset = extExpectedTS - uint64(refTS)
+					extRefTS = extExpectedTS
 					f.logger.Infow(
 						"calculating dummyStartTSOffset",
 						"preStartTime", f.preStartTime.String(),
 						"extFirstTS", f.extFirstTS,
-						"timeSinceFirst", timeSinceFirst,
+						"timeSinceFirst", timeSinceFirst.String(),
 						"rtpDiff", rtpDiff,
 						"extRefTS", extRefTS,
+						"incomingTS", extPkt.Packet.Timestamp,
+						"referenceLayerSpatial", f.referenceLayerSpatial,
 						"dummyStartTSOffset", f.dummyStartTSOffset,
 					)
 				}
 			}
 		}
 	}
-	extRefTS += f.dummyStartTSOffset
 
 	var extNextTS uint64
 	if f.lastSSRC == 0 {
@@ -1759,6 +1763,7 @@ func (f *Forwarder) processSourceSwitch(extPkt *buffer.ExtPacket, layer int32) e
 		"switchingAt", switchingAt.String(),
 		"layer", layer,
 		"extLastTS", extLastTS,
+		"lastMarker", rtpMungerState.LastMarker,
 		"extRefTS", extRefTS,
 		"dummyStartTSOffset", f.dummyStartTSOffset,
 		"referenceLayerSpatial", f.referenceLayerSpatial,
diff --git a/pkg/sfu/sequencer.go b/pkg/sfu/sequencer.go
index a78b23eb6..c876b63c9 100644
--- a/pkg/sfu/sequencer.go
+++ b/pkg/sfu/sequencer.go
@@ -237,7 +237,7 @@ func (s *sequencer) pushPadding(extStartSNInclusive uint64, extEndSNInclusive ui
 	s.Lock()
 	defer s.Unlock()
 
-	if s.snRangeMap == nil {
+	if s.snRangeMap == nil || !s.initialized {
 		return
 	}