WebRTC live stream(H264) error in Firefox, can't generate valid SDP answer

Question

I am trying to run H264 encoded live stream in Web Browser using Janus WebRTC Gateway. While testing with Chrome, the stream works fine but with firefox it shows ICE failed, add a TURN server and see about:webrtc for more details.

Following is my about:webrtc logs for firefox.

[ 6442450983 ] http://192.168.2.194:5000/ 15:18:19 GMT+0530 (IST)
PeerConnection ID: 1515491295667117 (id=6442450983 url=http://192.168.2.194:5000/)
ICE Stats
Local Candidate Remote Candidate    ICE State   Priority    Nominated   Selected    Bytes sent  Bytes received
ICE restarts:
ICE rollbacks:
SDP
Local SDP

v=0

o=mozilla...THIS_IS_SDPARTA-57.0.4 3500649212029345392 0 IN IP4 0.0.0.0

s=-

t=0 0

a=sendrecv

a=fingerprint:sha-256 11:44:F1:BD:D1:69:8E:17:E0:9A:AA:89:8E:76:9F:4E:09:E1:94:D0:37:34:EE:FE:DF:5E:FC:77:B0:4D:F7:53

a=ice-options:trickle

a=msid-semantic:WMS *

m=video 0 RTP/SAVPF 120

c=IN IP4 0.0.0.0

a=inactive

a=end-of-candidates

a=mid:video

a=rtpmap:120 VP8/90000

Remote SDP

v=0

o=- 1515491295396595 1515491295396595 IN IP4 106.51.68.195

s=-

t=0 0

a=sendrecv

a=group:BUNDLE video

a=msid-semantic:WMS janus

m=video 9 RTP/SAVPF 126

c=IN IP4 106.51.68.195

a=candidate:1 1 udp 2013266431 192.168.2.194 45887 typ host

a=candidate:2 1 udp 1677722111 106.51.68.195 45887 typ srflx raddr 192.168.2.194 rport 45887

a=sendonly

a=end-of-candidates

a=fingerprint:sha-256 D2:B9:31:8F:DF:24:D8:0E:ED:D2:EF:25:9E:AF:6F:B8:34:AE:53:9C:E6:F3:8F:F2:64:15:FA:E8:7F:53:2D:38

a=ice-options:trickle

a=ice-pwd:KsS99rsAZXj9lFd7psCT61

a=ice-ufrag:3tcw

a=mid:video

a=rtcp-fb:126 nack

a=rtcp-fb:126 goog-remb

a=rtcp-mux

a=rtpmap:126 H264/90000

a=setup:actpass

a=ssrc:3973486276 cname:janusvideo

a=ssrc:3973486276 msid:janus janusv0

a=ssrc:3973486276 mslabel:janus

a=ssrc:3973486276 label:janusv0

RTP Stats

I even tried adding following TURN Server

{urls: "turn:numb.viagenie.ca",
 username: "l1787875@mvrht.com",
 credential: "test"}

But the console error changes to ICE failed, your TURN server appears to be broken, see about:webrtc for more details, Keeping the about:webrtc logs same as before.

I figured out that somehow Firefox can't generate a valid answer for SDP offer generated by Janus. Created answer by Firefox has attribute rtpmap: 120 VP8/90000, whereas SDP offer made by Janus has attribute rtpmap: 127 H264/90000, which prevent Firefox to establish a SDP session with Janus. Chrome can generate the valid answer with rtpmap: 127 H264/90000 so it can display the stream perfectly.

I am using Mozilla firefox-57.0.4. Is there a way, I can get/ generate a valid SDP answer for incoming SDP offer from Janus?

It's strange that Chrome works but Firefox doesn't. Go to `about:config` in Firefox and see if `media.peerconnection.ice.relay_only` is set to `true`, which would force Firefox to only establish connections via relay (TURN). If it is, change it to `false` and try again. — jamix, Jan 09 '18 at 10:28
`media.peerconnection.ice.relay_only` is set to its default value only i.e. `false`. Is there anything else I need to check? — Rhythm Chopra, Jan 09 '18 at 10:33
You have pasted the SDP coming from Janus, can you also paste the SDP that Firefox sends? Another thing to try is instead of specifying the TURN, try specifying a public STUN server, e.g. `{ urls: "stun:stun.l.google.com:19302" }`. — jamix, Jan 09 '18 at 12:03
I am using the STUN server `{ urls: "stun:stun.l.google.com:19302" }` and no TURN server. I just used TURN to check for the console error `ICE failed, add a TURN server and see about:webrtc for more details` . But it didn't resolve the issue. Things are working fine with Chrome. — Rhythm Chopra, Jan 09 '18 at 12:56
And this is the log from `about:webrtc` in firefox. How can I obtain the SDP, you are asking? I don't have much experience with this. — Rhythm Chopra, Jan 09 '18 at 12:57

Francisco Fernández Herrera · Accepted Answer · 2018-03-10T03:10:56.673

This solution worked for me (last yellow message): https://groups.google.com/forum/#!topic/meetecho-janus/jKg5u9421kM

I'm using Janus and I was getting the same error in Firefox. The problem was about the SDP profile-level-id. I just had to replace it:

            // Create offer/answer now
             if(jsep === null || jsep === undefined) {
                     createOffer(handleId, media, callbacks);
             } else {
                     if(adapter.browserDetails.browser === "edge") {
                             // This is Edge, add an a=end-of-candidates at the end
                             jsep.sdp += "a=end-of-candidates\r\n";
                     }
                     var oldsdp = jsep["sdp"];
                     var pattern=/420029/gi;
                     var newsdp = oldsdp.replace(pattern,"42e01f");
                     Janus.log(newsdp);
                     jsep["sdp"]=newsdp;
                     config.pc.setRemoteDescription(
                                     new RTCSessionDescription(jsep),
                                     function() {
                                             Janus.log("Remote description accepted!");
                                             createAnswer(handleId, media, callbacks);
                                     }, callbacks.error);
             }
     }

WebRTC live stream(H264) error in Firefox, can't generate valid SDP answer

1 Answers1