Cannot match Confbridge channel ID with Sdp msid/label

Asterisk Asterisk WebRTC
1

Hi! I’m trying to add names to video streams in a conference based on this tutorial. It says it should be possible to match stream ids with channel ids by comparing them with the sdp msid/label (200 Ok Invite answer from Asterisk). I receive for instance the following sdp:

v=0
o=- 1382282775 4 IN IP4 192.168.1.30
s=Asterisk
c=IN IP4 192.168.1.30
t=0 0
a=msid-semantic:WMS *
a=group:BUNDLE 0 1
m=audio 19170 UDP/TLS/RTP/SAVPF 111 126
a=connection:new
a=setup:active
a=fingerprint:SHA-256 9F:91:00:89:BB:BD:2D:05:11:0B:7F:9B:8D:8F:F8:F9:70:9E:11:1A:69:B9:1B:10:46:82:42:EC:0A:5F:69:98
a=ice-ufrag:3309da5a1caea72009662dc82dcf0afb
a=ice-pwd:7e51ba6e398641ef0d4aebdc0cef98ca
a=candidate:Hc0a8011e 1 UDP 2130706431 192.168.1.30 19170 typ host
a=candidate:Hac130001 1 UDP 2130706431 172.19.0.1 19170 typ host
a=candidate:Hac120001 1 UDP 2130706431 172.18.0.1 19170 typ host
a=candidate:Hac110001 1 UDP 2130706431 172.17.0.1 19170 typ host
a=candidate:S5ed44178 1 UDP 1694498815 94.212.65.120 19170 typ srflx raddr 192.168.1.30 rport 19170
a=rtpmap:111 opus/48000/2
a=fmtp:111 useinbandfec=1
a=rtpmap:126 telephone-event/8000
a=fmtp:126 0-16
a=ptime:20
a=maxptime:20
a=sendrecv
a=rtcp-mux
a=ssrc:1461860839 cname:71a2c8d9-49a7-4ce6-b0ee-575344fe9551
a=msid:8e841d23-c1d0-46a8-bddd-0e51eb9a1cb3 363b75a6-9845-46c0-ae82-1e602d5d4d39
a=rtcp-fb:* transport-cc
a=mid:0
m=video 19170 UDP/TLS/RTP/SAVPF 96 98
a=connection:new
a=setup:active
a=fingerprint:SHA-256 9F:91:00:89:BB:BD:2D:05:11:0B:7F:9B:8D:8F:F8:F9:70:9E:11:1A:69:B9:1B:10:46:82:42:EC:0A:5F:69:98
a=ice-ufrag:3309da5a1caea72009662dc82dcf0afb
a=ice-pwd:7e51ba6e398641ef0d4aebdc0cef98ca
a=rtpmap:96 VP8/90000
a=rtpmap:98 VP9/90000
a=sendrecv
a=rtcp-mux
a=ssrc:1657929850 cname:a97eb52b-b4e6-455f-8642-053e889a690a
a=msid:8e841d23-c1d0-46a8-bddd-0e51eb9a1cb3 7a987370-62bc-48d7-91c7-9a80caca7685
a=rtcp-fb:* transport-cc
a=rtcp-fb:* ccm fir
a=rtcp-fb:* goog-remb
a=rtcp-fb:* nack
a=extmap:2 http://www.webrtc.org/experiments/rtp-hdrext/abs-send-time
a=extmap:3 http://www.ietf.org/id/draft-holmer-rmcat-transport-wide-cc-extensions-01
a=mid:1

The Confbridge event:

{
  "type": "ConfbridgeJoin",
  "timestamp": "2020-05-11T14:08:37.691+0000",
  "bridge": {
    "id": "fef59449-7c4d-488f-bc96-0d267d5f2ab1",
    "name": "guest",
    "creationtime": "2020-05-11T14:08:34.533+0000",
    "video_mode": "sfu"
  },
  "channels": [
    {
      "id": "1589206114.34",
      "name": "PJSIP/2000-0000000c",
      "state": "Up",
      "caller": {
        "name": "Bob",
        "number": "2000"
      },
      "creationtime": "2020-05-11T14:08:34.509+0000",
      "language": "en",
      "admin": false,
      "muted": false
    }
  ]
}

The channelId looks like 1589206114.34, while there is no label and only msid in the form of a UUID in the sdp. What am I missing here?

2

There is only a single participant in there, which would be the client itself. If you add additional participants does it then work as you expect?

3

My mistake. I expected the label attribute to be available on all media streams. I joined in with another Chromium profile using a fake webrtc device. This time, when I join the conference, I get:

{
  "type": "ConfbridgeWelcome",
  "timestamp": "2020-05-11T14:47:57.109+0000",
  "bridge": {
    "id": "0795863f-73cf-4dc0-955c-100533e54ada",
    "name": "guest",
    "creationtime": "2020-05-11T14:47:43.824+0000",
    "video_mode": "sfu"
  },
  "channels": [
    {
      "id": "1589208463.0",
      "name": "PJSIP/1000-00000000",
      "state": "Up",
      "caller": {
        "name": "Alice",
        "number": "1000"
      },
      "creationtime": "2020-05-11T14:47:43.794+0000",
      "language": "en",
      "admin": false,
      "muted": false
    },
    {
      "id": "1589208473.3",
      "name": "PJSIP/2000-00000001",
      "state": "Up",
      "caller": {
        "name": "Bob",
        "number": "2000"
      },
      "creationtime": "2020-05-11T14:47:53.834+0000",
      "language": "en",
      "admin": false,
      "muted": false
    }
  ]
}

With SDP:

v=0
o=- 3179366085 5 IN IP4 192.168.1.30
s=Asterisk
c=IN IP4 192.168.1.30
t=0 0
a=msid-semantic:WMS *
a=group:BUNDLE 0 1 video-2
m=audio 10298 UDP/TLS/RTP/SAVPF 111 126
a=connection:existing
a=setup:actpass
a=fingerprint:SHA-256 A0:7D:B3:05:E3:86:4F:70:A7:13:AB:9D:E3:D8:8A:52:83:3B:AA:E1:2C:76:67:51:06:9E:CA:16:85:B8:FA:0C
a=ice-ufrag:1c628eb866cd73d32c2903cb1e82712f
a=ice-pwd:78fcd2984992acb35239b75b5302d0da
a=candidate:Hc0a8011e 1 UDP 2130706431 192.168.1.30 10298 typ host
a=candidate:Hac130001 1 UDP 2130706431 172.19.0.1 10298 typ host
a=candidate:Hac120001 1 UDP 2130706431 172.18.0.1 10298 typ host
a=candidate:Hac110001 1 UDP 2130706431 172.17.0.1 10298 typ host
a=candidate:S5ed44178 1 UDP 1694498815 94.212.65.120 10298 typ srflx raddr 192.168.1.30 rport 10298
a=rtpmap:111 opus/48000/2
a=fmtp:111 useinbandfec=1
a=rtpmap:126 telephone-event/8000
a=fmtp:126 0-16
a=ptime:20
a=maxptime:20
a=sendrecv
a=rtcp-mux
a=ssrc:766611375 cname:20d8d907-ede7-454f-bf12-73a4723ce43d
a=msid:00844aaa-28a1-4ac2-8161-25f3cf681f60 49e72ac3-11a8-4cf2-a4dc-d62e23a0eda0
a=rtcp-fb:* transport-cc
a=mid:0
m=video 10298 UDP/TLS/RTP/SAVPF 96 98
a=connection:existing
a=setup:actpass
a=fingerprint:SHA-256 A0:7D:B3:05:E3:86:4F:70:A7:13:AB:9D:E3:D8:8A:52:83:3B:AA:E1:2C:76:67:51:06:9E:CA:16:85:B8:FA:0C
a=ice-ufrag:1c628eb866cd73d32c2903cb1e82712f
a=ice-pwd:78fcd2984992acb35239b75b5302d0da
a=rtpmap:96 VP8/90000
a=rtpmap:98 VP9/90000
a=sendrecv
a=rtcp-mux
a=ssrc:715839767 cname:6f9112aa-20e2-48f6-bacd-1206b1ee3f29
a=msid:00844aaa-28a1-4ac2-8161-25f3cf681f60 acb6017b-4499-4ad1-b8b4-ed4b117738dd
a=rtcp-fb:* transport-cc
a=rtcp-fb:* ccm fir
a=rtcp-fb:* goog-remb
a=rtcp-fb:* nack
a=extmap:2 http://www.webrtc.org/experiments/rtp-hdrext/abs-send-time
a=extmap:3 http://www.ietf.org/id/draft-holmer-rmcat-transport-wide-cc-extensions-01
a=mid:1
m=video 10298 UDP/TLS/RTP/SAVPF 96 98
a=connection:existing
a=setup:actpass
a=fingerprint:SHA-256 A0:7D:B3:05:E3:86:4F:70:A7:13:AB:9D:E3:D8:8A:52:83:3B:AA:E1:2C:76:67:51:06:9E:CA:16:85:B8:FA:0C
a=ice-ufrag:1c628eb866cd73d32c2903cb1e82712f
a=ice-pwd:78fcd2984992acb35239b75b5302d0da
a=rtpmap:96 VP8/90000
a=rtpmap:98 VP9/90000
a=sendonly
a=rtcp-mux
a=ssrc:1036794790 cname:9387c5d2-1c83-455c-aa6d-ded629e43e28
a=msid:0d23980c-37fa-4a20-b74a-43e527bb50ad 7d1badb2-f010-486b-b9b1-a8ef2198bfd3
a=label:1589208463.0
a=rtcp-fb:* transport-cc
a=rtcp-fb:* ccm fir
a=rtcp-fb:* goog-remb
a=rtcp-fb:* nack
a=extmap:2 http://www.webrtc.org/experiments/rtp-hdrext/abs-send-time
a=extmap:3 http://www.ietf.org/id/draft-holmer-rmcat-transport-wide-cc-extensions-01
a=mid:video-2

It contains the label attribute, which should be enough to make the match. Thanks for the help!

4

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