install go2rtc on bob

installs_on_host/go2rtc/pkg/webrtc/client.go

@@ -0,0 +1,145 @@
+package webrtc
+
+import (
+	"github.com/AlexxIT/go2rtc/pkg/core"
+	"github.com/pion/sdp/v3"
+	"github.com/pion/webrtc/v4"
+)
+
+func (c *Conn) CreateOffer(medias []*core.Media) (string, error) {
+	// 1. Create transeivers with proper kind and direction
+	for _, media := range medias {
+		var err error
+		switch media.Direction {
+		case core.DirectionRecvonly:
+			_, err = c.pc.AddTransceiverFromKind(
+				webrtc.NewRTPCodecType(media.Kind),
+				webrtc.RTPTransceiverInit{Direction: webrtc.RTPTransceiverDirectionRecvonly},
+			)
+		case core.DirectionSendonly:
+			_, err = c.pc.AddTransceiverFromTrack(
+				NewTrack(media.Kind),
+				webrtc.RTPTransceiverInit{Direction: webrtc.RTPTransceiverDirectionSendonly},
+			)
+		case core.DirectionSendRecv:
+			// default transceiver is sendrecv
+			_, err = c.pc.AddTransceiverFromTrack(NewTrack(media.Kind))
+		default:
+			// Nest cameras require data channel
+			_, err = c.pc.CreateDataChannel(media.Kind, nil)
+		}
+
+		if err != nil {
+			return "", err
+		}
+	}
+
+	// 2. Create local offer
+	desc, err := c.pc.CreateOffer(nil)
+	if err != nil {
+		return "", err
+	}
+
+	// 3. Start gathering phase
+	if err = c.pc.SetLocalDescription(desc); err != nil {
+		return "", err
+	}
+
+	return c.pc.LocalDescription().SDP, nil
+}
+
+func (c *Conn) CreateCompleteOffer(medias []*core.Media) (string, error) {
+	if _, err := c.CreateOffer(medias); err != nil {
+		return "", err
+	}
+
+	<-webrtc.GatheringCompletePromise(c.pc)
+	return c.pc.LocalDescription().SDP, nil
+}
+
+func (c *Conn) SetAnswer(answer string) (err error) {
+	desc := webrtc.SessionDescription{
+		Type: webrtc.SDPTypeAnswer,
+		SDP:  fakeFormatsInAnswer(c.pc.LocalDescription().SDP, answer),
+	}
+	if err = c.pc.SetRemoteDescription(desc); err != nil {
+		return err
+	}
+
+	sd := &sdp.SessionDescription{}
+	if err = sd.Unmarshal([]byte(answer)); err != nil {
+		return err
+	}
+
+	c.Medias = UnmarshalMedias(sd.MediaDescriptions)
+
+	return nil
+}
+
+// fakeFormatsInAnswer - fix pion bug with remote SDP parsing:
+// pion will process formats only from first media of each kind
+// so we add all formats from first offer media to the first answer media
+func fakeFormatsInAnswer(offer, answer string) string {
+	sd2 := &sdp.SessionDescription{}
+	if err := sd2.Unmarshal([]byte(answer)); err != nil {
+		return answer
+	}
+
+	// check if answer has recvonly audio
+	var ok bool
+	for _, md2 := range sd2.MediaDescriptions {
+		if md2.MediaName.Media == "audio" {
+			if _, ok = md2.Attribute("recvonly"); ok {
+				break
+			}
+		}
+	}
+	if !ok {
+		return answer
+	}
+
+	sd1 := &sdp.SessionDescription{}
+	if err := sd1.Unmarshal([]byte(offer)); err != nil {
+		return answer
+	}
+
+	var formats []string
+	var attrs []sdp.Attribute
+
+	for _, md1 := range sd1.MediaDescriptions {
+		if md1.MediaName.Media == "audio" {
+			for _, attr := range md1.Attributes {
+				switch attr.Key {
+				case "rtpmap", "fmtp", "rtcp-fb", "extmap":
+					attrs = append(attrs, attr)
+				}
+			}
+
+			formats = md1.MediaName.Formats
+			break
+		}
+	}
+
+	for _, md2 := range sd2.MediaDescriptions {
+		if md2.MediaName.Media == "audio" {
+			for _, attr := range md2.Attributes {
+				switch attr.Key {
+				case "rtpmap", "fmtp", "rtcp-fb", "extmap":
+				default:
+					attrs = append(attrs, attr)
+				}
+			}
+
+			md2.MediaName.Formats = formats
+			md2.Attributes = attrs
+			break
+		}
+	}
+
+	b, err := sd2.Marshal()
+	if err != nil {
+		return answer
+	}
+
+	return string(b)
+}