Adds support for the Absolute Capture Time extension

engine.go

@@ -342,13 +342,14 @@ func (e *RTCEngine) configure(
 func (e *RTCEngine) createPublisherPCLocked(configuration webrtc.Configuration) error {
 	var err error
 	if e.publisher, err = NewPCTransport(PCTransportParams{
-		Configuration:        configuration,
-		Codecs:               e.connParams.Codecs,
-		RetransmitBufferSize: e.connParams.RetransmitBufferSize,
-		Pacer:                e.connParams.Pacer,
-		Interceptors:         e.connParams.Interceptors,
-		OnRTTUpdate:          e.setRTT,
-		IsSender:             true,
+		Configuration:              configuration,
+		Codecs:                     e.connParams.Codecs,
+		RetransmitBufferSize:       e.connParams.RetransmitBufferSize,
+		Pacer:                      e.connParams.Pacer,
+		Interceptors:               e.connParams.Interceptors,
+		IncludeDefaultInterceptors: e.connParams.IncludeDefaultInterceptors,
+		OnRTTUpdate:                e.setRTT,
+		IsSender:                   true,
 	}); err != nil {
 		return err
 	}
@@ -429,9 +430,11 @@ func (e *RTCEngine) createSubscriberPCLocked(configuration webrtc.Configuration)
 
 	var err error
 	if e.subscriber, err = NewPCTransport(PCTransportParams{
-		Configuration:        configuration,
-		Codecs:               e.connParams.Codecs,
-		RetransmitBufferSize: e.connParams.RetransmitBufferSize,
+		Configuration:              configuration,
+		Codecs:                     e.connParams.Codecs,
+		RetransmitBufferSize:       e.connParams.RetransmitBufferSize,
+		Interceptors:               e.connParams.Interceptors,
+		IncludeDefaultInterceptors: e.connParams.IncludeDefaultInterceptors,
 	}); err != nil {
 		return err
 	}

room.go

@@ -131,6 +131,14 @@ func WithInterceptors(interceptors []interceptor.Factory) ConnectOption {
 	}
 }
 
+// WithIncludeDefaultInterceptors sets whether to register default interceptors
+// along with custom interceptors.
+func WithIncludeDefaultInterceptors(include bool) ConnectOption {
+	return func(p *signalling.ConnectParams) {
+		p.IncludeDefaultInterceptors = include
+	}
+}
+
 // WithICETransportPolicy sets the ICE transport policy (UDP, Relay, etc.).
 func WithICETransportPolicy(iceTransportPolicy webrtc.ICETransportPolicy) ConnectOption {
 	return func(p *signalling.ConnectParams) {

signalling/interfaces.go

@@ -82,6 +82,8 @@ type ConnectParams struct {
 
 	Interceptors []interceptor.Factory
 
+	IncludeDefaultInterceptors bool
+
 	ICETransportPolicy webrtc.ICETransportPolicy
 
 	// internal use

transport.go

@@ -73,11 +73,12 @@ type PCTransportParams struct {
 	Configuration webrtc.Configuration
 	Codecs        []webrtc.RTPCodecParameters
 
-	RetransmitBufferSize uint16
-	Pacer                pacer.Factory
-	Interceptors         []interceptor.Factory
-	OnRTTUpdate          func(rtt uint32)
-	IsSender             bool
+	RetransmitBufferSize       uint16
+	Pacer                      pacer.Factory
+	Interceptors               []interceptor.Factory
+	IncludeDefaultInterceptors bool
+	OnRTTUpdate                func(rtt uint32)
+	IsSender                   bool
 }
 
 func (t *PCTransport) registerDefaultInterceptors(params PCTransportParams, i *interceptor.Registry) error {
@@ -160,7 +161,11 @@ func NewPCTransport(params PCTransportParams) (*PCTransport, error) {
 	if err := m.RegisterHeaderExtension(sdesRtpStreamIdExtension, webrtc.RTPCodecTypeVideo); err != nil {
 		return nil, err
 	}
-
+	absCaptureTimeURI := "http://www.webrtc.org/experiments/rtp-hdrext/abs-capture-time"
+	absCaptureTimeExtension := webrtc.RTPHeaderExtensionCapability{URI: absCaptureTimeURI}
+	if err := m.RegisterHeaderExtension(absCaptureTimeExtension, webrtc.RTPCodecTypeAudio); err != nil {
+		return nil, err
+	}
 	i := &interceptor.Registry{}
 
 	t := &PCTransport{
@@ -172,6 +177,12 @@ func NewPCTransport(params PCTransportParams) (*PCTransport, error) {
 		for _, c := range params.Interceptors {
 			i.Add(c)
 		}
+		if params.IncludeDefaultInterceptors {
+			err := t.registerDefaultInterceptors(params, i)
+			if err != nil {
+				return nil, err
+			}
+		}
 	} else {
 		err := t.registerDefaultInterceptors(params, i)
 		if err != nil {