transfer from non-null for codec change (#3464)

pkg/sfu/forwarder.go

@@ -344,13 +344,13 @@ func (f *Forwarder) DetermineCodec(codec webrtc.RTPCodecCapability, extensions [
 		isDDAvailable := ddAvailable(extensions)
 		if isDDAvailable {
 			if f.vls != nil {
-				f.vls = videolayerselector.NewDependencyDescriptorFromNull(f.vls)
+				f.vls = videolayerselector.NewDependencyDescriptorFromOther(f.vls)
 			} else {
 				f.vls = videolayerselector.NewDependencyDescriptor(f.logger)
 			}
 		} else {
 			if f.vls != nil {
-				f.vls = videolayerselector.NewVP9FromNull(f.vls)
+				f.vls = videolayerselector.NewVP9FromOther(f.vls)
 			} else {
 				f.vls = videolayerselector.NewVP9(f.logger)
 			}
@@ -362,7 +362,7 @@ func (f *Forwarder) DetermineCodec(codec webrtc.RTPCodecCapability, extensions [
 		isDDAvailable := ddAvailable(extensions)
 		if isDDAvailable {
 			if f.vls != nil {
-				f.vls = videolayerselector.NewDependencyDescriptorFromNull(f.vls)
+				f.vls = videolayerselector.NewDependencyDescriptorFromOther(f.vls)
 			} else {
 				f.vls = videolayerselector.NewDependencyDescriptor(f.logger)
 			}

pkg/sfu/videolayerselector/dependencydescriptor.go

@@ -50,11 +50,30 @@ func NewDependencyDescriptor(logger logger.Logger) *DependencyDescriptor {
 	}
 }
 
-func NewDependencyDescriptorFromNull(vls VideoLayerSelector) *DependencyDescriptor {
-	return &DependencyDescriptor{
-		Base:      vls.(*Null).Base,
-		decisions: NewSelectorDecisionCache(256, 80),
-		fnWrapper: FrameNumberWrapper{logger: vls.(*Null).logger},
+func NewDependencyDescriptorFromOther(vls VideoLayerSelector) *DependencyDescriptor {
+	switch vls := vls.(type) {
+	case *Null:
+		return &DependencyDescriptor{
+			Base: vls.Base,
+		}
+
+	case *Simulcast:
+		return &DependencyDescriptor{
+			Base: vls.Base,
+		}
+
+	case *DependencyDescriptor:
+		return &DependencyDescriptor{
+			Base: vls.Base,
+		}
+
+	case *VP9:
+		return &DependencyDescriptor{
+			Base: vls.Base,
+		}
+
+	default:
+		return nil
 	}
 }
 

pkg/sfu/videolayerselector/simulcast.go

@@ -35,6 +35,7 @@ func NewSimulcastFromOther(vls VideoLayerSelector) *Simulcast {
 		return &Simulcast{
 			Base: vls.Base,
 		}
+
 	case *Simulcast:
 		return &Simulcast{
 			Base: vls.Base,

pkg/sfu/videolayerselector/vp9.go

@@ -30,9 +30,30 @@ func NewVP9(logger logger.Logger) *VP9 {
 	}
 }
 
-func NewVP9FromNull(vls VideoLayerSelector) *VP9 {
-	return &VP9{
-		Base: vls.(*Null).Base,
+func NewVP9FromOther(vls VideoLayerSelector) *VP9 {
+	switch vls := vls.(type) {
+	case *Null:
+		return &VP9{
+			Base: vls.Base,
+		}
+
+	case *Simulcast:
+		return &VP9{
+			Base: vls.Base,
+		}
+
+	case *DependencyDescriptor:
+		return &VP9{
+			Base: vls.Base,
+		}
+
+	case *VP9:
+		return &VP9{
+			Base: vls.Base,
+		}
+
+	default:
+		return nil
 	}
 }