title: iOS Swift WebRTC - Failed to set remote offer sdp: Failed to set remote video description send parameters
body: <p>I am trying webRTC video call between iPhone devices. One application is creating the offer SDP as below. When i tried to set this SDP, am getting error in another application as </p>
  
  <blockquote>
    <p>Error Domain=org.webrtc.RTCPeerConnection Code=-1 "Failed to set remote offer sdp: Failed to set remote video description send parameters." UserInfo={NSLocalizedDescription=Failed to set remote offer sdp: Failed to set remote video description send parameters.}</p>
  </blockquote>
  
  <p>Following is the code used to set the offer and create the answer. The second line <code>self.peerConnection?.setRemoteDescription</code> throws error.</p>
  
  <pre><code> let sessionDescription = RTCSessionDescription(type: .offer, sdp: remoteSdp)
          self.peerConnection?.setRemoteDescription(sessionDescription, completionHandler: { [weak self] (error) in
              guard let this = self else { return }
              if let error = error {
                  this.delegate?.webrtcClient(client: this, didReceiveError: error)
              } else {
                  this.handleRemoteDescriptionSet()
                  // create answer
                  peerConnection.answer(for: this.callConstraint, completionHandler:
                      { (sdp, error) in
                          if let error = error {
                              this.delegate?.webrtcClient(client: this, didReceiveError: error)
                          } else {
                              this.handleSdpGenerated(sdpDescription: sdp)
                          }
                  })
              }
          })
  </code></pre>
  
  <p>Following is the Offer SDP format</p>
  
  <pre><code>v=0
  
  o=- 271054486825926104 2 IN IP4 127.0.0.1
  
  s=-
  
  t=0 0
  
  a=group:BUNDLE video
  
  a=msid-semantic: WMS ARDAMS
  
  m=video 9 UDP/TLS/RTP/SAVPF 100 101 116 117 96
  
  c=IN IP4 0.0.0.0
  
  a=rtcp:9 IN IP4 0.0.0.0
  
  a=ice-ufrag:mwCLNm7ZLzmDrtCu
  
  a=ice-pwd:+alfGXoarzyKjISWRYAGyIH4
  
  a=fingerprint:sha-256 44:0D:11:54:EC:62:CD:51:D0:E3:BB:A5:47:35:D1:27:48:4E:08:3B:AD:98:72:98:02:BA:06:C8:CC:12:0E:C0
  
  a=setup:actpass
  
  a=mid:video
  
  a=extmap:2 urn:ietf:params:rtp-hdrext:toffset
  
  a=extmap:3 http://www.webrtc.org/experiments/rtp-hdrext/abs-send-time
  
  a=extmap:4 urn:3gpp:video-orientation
  
  a=sendrecv
  
  a=rtcp-mux
  
  a=rtpmap:100 VP8/90000
  
  a=rtcp-fb:100 ccm fir
  
  a=rtcp-fb:100 nack
  
  a=rtcp-fb:100 nack pli
  
  a=rtcp-fb:100 goog-remb
  
  a=rtpmap:101 VP9/90000
  
  a=rtcp-fb:101 ccm fir
  
  a=rtcp-fb:101 nack
  
  a=rtcp-fb:101 nack pli
  
  a=rtcp-fb:101 goog-remb
  
  a=rtpmap:116 red/90000
  
  a=rtpmap:117 ulpfec/90000
  
  a=rtpmap:96 rtx/90000
  
  a=fmtp:96 apt=100
  
  a=ssrc-group:FID 1767367305 3714792746
  
  a=ssrc:1767367305 cname:9wPGj45IHVxtvO6N
  
  a=ssrc:1767367305 msid:ARDAMS ARDAMSv0
  
  a=ssrc:1767367305 mslabel:ARDAMS
  
  a=ssrc:1767367305 label:ARDAMSv0
  
  a=ssrc:3714792746 cname:9wPGj45IHVxtvO6N
  
  a=ssrc:3714792746 msid:ARDAMS ARDAMSv0
  
  a=ssrc:3714792746 mslabel:ARDAMS
  
  a=ssrc:3714792746 label:ARDAMSv0
  </code></pre>