From a11944f84d681adaef32ed3c7ae45527c538f330 Mon Sep 17 00:00:00 2001
From: Raja Subramanian <raja.gobi@tutanota.com>
Date: Wed, 19 Apr 2023 16:21:16 +0530
Subject: [PATCH] Restore VP8 munger state properly. (#1634)

* Restore VP8 munger state properly.

* clean up
---
 pkg/sfu/codecmunger/null.go | 8 +++++++-
 pkg/sfu/codecmunger/vp8.go  | 6 ++++++
 pkg/sfu/forwarder.go        | 2 +-
 3 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/pkg/sfu/codecmunger/null.go b/pkg/sfu/codecmunger/null.go
index e6b3f00cb..f9c327a2d 100644
--- a/pkg/sfu/codecmunger/null.go
+++ b/pkg/sfu/codecmunger/null.go
@@ -6,6 +6,7 @@ import (
 )
 
 type Null struct {
+	seededState interface{}
 }
 
 func NewNull(_logger logger.Logger) *Null {
@@ -16,7 +17,12 @@ func (n *Null) GetState() interface{} {
 	return nil
 }
 
-func (n *Null) SeedState(_state interface{}) {
+func (n *Null) SeedState(state interface{}) {
+	n.seededState = state
+}
+
+func (n *Null) GetSeededState() interface{} {
+	return n.seededState
 }
 
 func (n *Null) SetLast(_extPkt *buffer.ExtPacket) {
diff --git a/pkg/sfu/codecmunger/vp8.go b/pkg/sfu/codecmunger/vp8.go
index 271dac71e..dbe8f0665 100644
--- a/pkg/sfu/codecmunger/vp8.go
+++ b/pkg/sfu/codecmunger/vp8.go
@@ -64,6 +64,12 @@ func NewVP8(logger logger.Logger) *VP8 {
 	}
 }
 
+func NewVP8FromNull(cm CodecMunger, logger logger.Logger) *VP8 {
+	v := NewVP8(logger)
+	v.SeedState(cm.(*Null).GetSeededState())
+	return v
+}
+
 func (v *VP8) GetState() interface{} {
 	return VP8State{
 		ExtLastPictureId: v.extLastPictureId,
diff --git a/pkg/sfu/forwarder.go b/pkg/sfu/forwarder.go
index ab4e83dfb..069132850 100644
--- a/pkg/sfu/forwarder.go
+++ b/pkg/sfu/forwarder.go
@@ -256,7 +256,7 @@ func (f *Forwarder) DetermineCodec(codec webrtc.RTPCodecCapability, extensions [
 
 	switch strings.ToLower(codec.MimeType) {
 	case "video/vp8":
-		f.codecMunger = codecmunger.NewVP8(f.logger)
+		f.codecMunger = codecmunger.NewVP8FromNull(f.codecMunger, f.logger)
 		if f.vls != nil {
 			f.vls = videolayerselector.NewSimulcastFromNull(f.vls)
 		} else {