From b85ff8f063703c8fa6b6561d49a7dd179781a097 Mon Sep 17 00:00:00 2001
From: cnderrauber <zengjie9004@gmail.com>
Date: Mon, 4 Sep 2023 12:39:14 +0800
Subject: [PATCH] Support non-SVC AV1 track publishing (#2030)

---
 pkg/sfu/downtrack.go |  5 ++++-
 pkg/sfu/forwarder.go | 38 +++++++++++++++++++++++++-------------
 2 files changed, 29 insertions(+), 14 deletions(-)

diff --git a/pkg/sfu/downtrack.go b/pkg/sfu/downtrack.go
index 44414d7c8..f126847bc 100644
--- a/pkg/sfu/downtrack.go
+++ b/pkg/sfu/downtrack.go
@@ -677,7 +677,10 @@ func (d *DownTrack) WriteRTP(extPkt *buffer.ExtPacket, layer int32) error {
 		return err
 	}
 
-	extensions := []pacer.ExtensionData{{ID: uint8(d.dependencyDescriptorExtID), Payload: tp.ddBytes}}
+	var extensions []pacer.ExtensionData
+	if tp.ddBytes != nil {
+		extensions = []pacer.ExtensionData{{ID: uint8(d.dependencyDescriptorExtID), Payload: tp.ddBytes}}
+	}
 	if d.playoutDelayExtID != 0 && !d.playoudDelayAcked.Load() {
 		if val := d.playoutDelayBytes.Load(); val != nil {
 			extensions = append(extensions, pacer.ExtensionData{ID: uint8(d.playoutDelayExtID), Payload: val.([]byte)})
diff --git a/pkg/sfu/forwarder.go b/pkg/sfu/forwarder.go
index 9421f238c..567465ce9 100644
--- a/pkg/sfu/forwarder.go
+++ b/pkg/sfu/forwarder.go
@@ -273,6 +273,15 @@ func (f *Forwarder) DetermineCodec(codec webrtc.RTPCodecCapability, extensions [
 	}
 	f.codec = codec
 
+	ddAvailable := func(exts []webrtc.RTPHeaderExtensionParameter) bool {
+		for _, ext := range exts {
+			if ext.URI == dd.ExtensionURI {
+				return true
+			}
+		}
+		return false
+	}
+
 	switch strings.ToLower(codec.MimeType) {
 	case "video/vp8":
 		f.codecMunger = codecmunger.NewVP8FromNull(f.codecMunger, f.logger)
@@ -289,15 +298,8 @@ func (f *Forwarder) DetermineCodec(codec webrtc.RTPCodecCapability, extensions [
 			f.vls = videolayerselector.NewSimulcast(f.logger)
 		}
 	case "video/vp9":
-		isDDAvailable := false
-	searchDone:
-		for _, ext := range extensions {
-			switch ext.URI {
-			case dd.ExtensionURI:
-				isDDAvailable = true
-				break searchDone
-			}
-		}
+		isDDAvailable := ddAvailable(extensions)
+
 		if isDDAvailable {
 			if f.vls != nil {
 				f.vls = videolayerselector.NewDependencyDescriptorFromNull(f.vls)
@@ -314,12 +316,22 @@ func (f *Forwarder) DetermineCodec(codec webrtc.RTPCodecCapability, extensions [
 		// SVC-TODO: Support for VP9 simulcast. When DD is not available, have to pick selector based on VP9 SVC or Simulcast
 	case "video/av1":
 		// DD-TODO : we only enable dd layer selector for av1/vp9 now, in the future we can enable it for vp8 too
-		if f.vls != nil {
-			f.vls = videolayerselector.NewDependencyDescriptorFromNull(f.vls)
+
+		isDDAvailable := ddAvailable(extensions)
+		if isDDAvailable {
+			if f.vls != nil {
+				f.vls = videolayerselector.NewDependencyDescriptorFromNull(f.vls)
+			} else {
+				f.vls = videolayerselector.NewDependencyDescriptor(f.logger)
+			}
 		} else {
-			f.vls = videolayerselector.NewDependencyDescriptor(f.logger)
+			if f.vls != nil {
+				f.vls = videolayerselector.NewSimulcastFromNull(f.vls)
+			} else {
+				f.vls = videolayerselector.NewSimulcast(f.logger)
+			}
 		}
-		// SVC-TODO: Support for AV1 Simulcast or just single spatial layer - won't have DD in that case
+		// SVC-TODO: Support for AV1 Simulcast
 	}
 }