WIP: simplify interface to TWCC 3/4

pkg/cc/interceptor.go

@@ -61,27 +61,37 @@ func (f *InterceptorFactory) OnNewPeerConnection(cb NewPeerConnectionCallback) {
 }
 
 // NewInterceptor returns a new CC interceptor
+// Don't call this, call [NewSingleInterceptor] instead.
 func (f *InterceptorFactory) NewInterceptor(id string) (interceptor.Interceptor, error) {
 	bwe, err := f.bweFactory()
 	if err != nil {
 		return nil, err
 	}
+	i, err := NewSingleInterceptor(bwe, f.opts...)
+	if err != nil {
+		return nil, err
+	}
+
+	if f.addPeerConnection != nil {
+		f.addPeerConnection(id, i.estimator)
+	}
+	return i, nil
+}
+
+// NewSingleInterceptor returns a new CC interceptor
+func NewSingleInterceptor(bwe BandwidthEstimator, options ...Option) (*Interceptor, error) {
 	i := &Interceptor{
 		NoOp:      interceptor.NoOp{},
 		estimator: bwe,
 		feedback:  make(chan []rtcp.Packet),
 		close:     make(chan struct{}),
 	}
 
-	for _, opt := range f.opts {
+	for _, opt := range options {
 		if err := opt(i); err != nil {
 			return nil, err
 		}
 	}
-
-	if f.addPeerConnection != nil {
-		f.addPeerConnection(id, i.estimator)
-	}
 	return i, nil
 }
 

registry.go

@@ -14,12 +14,17 @@ func (r *Registry) Add(f Factory) {
 }
 
 // Build constructs a single Interceptor from a InterceptorRegistry
-func (r *Registry) Build(id string) (Interceptor, error) {
+// The extra interceptors are added to the chain before the ones specified
+// by the registry.
+func (r *Registry) Build(id string, extra... Interceptor) (Interceptor, error) {
 	if len(r.factories) == 0 {
 		return &NoOp{}, nil
 	}
 
 	interceptors := []Interceptor{}
+
+	interceptors = append(interceptors, extra...)
+
 	for _, f := range r.factories {
 		i, err := f.NewInterceptor(id)
 		if err != nil {