Support multiple codecs for WebRTC producer

pkg/webrtc/producer.go

@@ -1,6 +1,7 @@
 package webrtc
 
 import (
+	"github.com/AlexxIT/go2rtc/pkg/core"
 	"github.com/AlexxIT/go2rtc/pkg/streamer"
 	"github.com/pion/rtp"
 	"github.com/pion/webrtc/v3"
@@ -48,23 +49,14 @@ func (c *Conn) getProducerSendTrack(media *streamer.Media, codec *streamer.Codec
 		return nil
 	}
 
-	oldTrack := sender.Track()
-	track := &Track{
-		kind:        media.Kind,
-		payloadType: codec.PayloadType,
-
-		id:       oldTrack.ID(),
-		rid:      oldTrack.RID(),
-		streamID: oldTrack.StreamID(),
-	}
-
-	if err := sender.ReplaceTrack(track); err != nil {
+	track, ok := sender.Track().(*Track)
+	if !ok {
 		return nil
 	}
 
 	push := func(packet *rtp.Packet) error {
 		c.send += packet.MarshalSize()
-		return track.WriteRTP(packet)
+		return track.WriteRTP(codec.PayloadType, packet)
 	}
 
 	return streamer.NewTrack(media, codec).Bind(push)
@@ -82,23 +74,28 @@ func (c *Conn) getTranseiver(mid string) *webrtc.RTPTransceiver {
 type Track struct {
 	kind     string
 	id       string
-	rid         string
 	streamID string
-	payloadType byte
 	sequence uint16
 	ssrc     uint32
 	writer   webrtc.TrackLocalWriter
 }
 
+func NewTrack(kind string) *Track {
+	return &Track{
+		kind:     kind,
+		id:       core.RandString(16),
+		streamID: core.RandString(16),
+	}
+}
+
 func (t *Track) Bind(context webrtc.TrackLocalContext) (webrtc.RTPCodecParameters, error) {
 	t.ssrc = uint32(context.SSRC())
 	t.writer = context.WriteStream()
 
 	for _, parameters := range context.CodecParameters() {
-		if byte(parameters.PayloadType) == t.payloadType {
+		// return first parameters
 		return parameters, nil
 	}
-	}
 
 	return webrtc.RTPCodecParameters{}, nil
 }
@@ -112,7 +109,7 @@ func (t *Track) ID() string {
 }
 
 func (t *Track) RID() string {
-	return t.rid
+	return "" // don't know what it is
 }
 
 func (t *Track) StreamID() string {
@@ -123,13 +120,13 @@ func (t *Track) Kind() webrtc.RTPCodecType {
 	return webrtc.NewRTPCodecType(t.kind)
 }
 
-func (t *Track) WriteRTP(packet *rtp.Packet) error {
+func (t *Track) WriteRTP(payloadType uint8, packet *rtp.Packet) error {
 	// important to have internal counter if input packets from different sources
 	t.sequence++
 
 	header := packet.Header
 	header.SSRC = t.ssrc
-	header.PayloadType = t.payloadType
+	header.PayloadType = payloadType
 	header.SequenceNumber = t.sequence
 	_, err := t.writer.WriteRTP(&header, packet.Payload)
 	return err

pkg/webrtc/server.go

@@ -43,15 +43,18 @@ func (c *Conn) GetAnswer() (answer string, err error) {
 
 		for _, md := range sd.MediaDescriptions {
 			for _, attr := range md.Attributes {
+				var direction webrtc.RTPTransceiverDirection
 				switch attr.Key {
 				case "recvonly":
-					_, _ = c.pc.AddTransceiverFromKind(
-						webrtc.NewRTPCodecType(md.MediaName.Media),
-						webrtc.RTPTransceiverInit{Direction: webrtc.RTPTransceiverDirectionSendonly},
-					)
+					direction = webrtc.RTPTransceiverDirectionSendonly
 				case "sendrecv":
-					_, _ = c.pc.AddTransceiverFromKind(
-						webrtc.NewRTPCodecType(md.MediaName.Media),
+					direction = webrtc.RTPTransceiverDirectionSendrecv
+				}
+
+				if direction > 0 {
+					_, _ = c.pc.AddTransceiverFromTrack(
+						NewTrack(md.MediaName.Media),
+						webrtc.RTPTransceiverInit{Direction: direction},
 					)
 				}
 			}