1646092 - ICE never nominates/selects on calls with Chrome with RTX enabled and only a microphone present

Status: RESOLVED FIXED

(Core :: WebRTC, defect, P3)

Description

[Dan Minor [:dminor]]

I ran into this while testing Bug 1644577, on a Firefox <-> Chrome call, using https://whereby.com/dminor, with RTX enabled and only a microphone as an input, ICE would consistently succeed, but never nominate or select a candidate. Using Wireshark, I see no RTP traffic at all.

Firefox <-> Firefox and Firefox <-> Chrome with RTX disabled or camera+microphone present all succeed.

Comment 1

[Nils Ohlmeier [:drno]]

I have no idea what is going on here, but it will be very important to test both combinations of:

• Firefox enters the room first followed by Chrome
• Chrome enters the room first followed by Firefox
  because in these two scenarios the offerer changes and that (normally) also changes which browser gets be the ICE controller. The result of the above combinations will tell you if this is a Firefox or a Chrome bug.

Comment 2

[Byron Campen [:bwc]]

I am not having any luck reproducing this. Does this only happen on devices that do not have a camera? Can you attach about:webrtc and a packet capture here?

Comment 3

[Dan Minor [:dminor]]

Attachment: about:webrtc

Comment 4

[Dan Minor [:dminor]]

Attachment: Wireshark packet capture

Comment 5

[Dan Minor [:dminor]]

This only reproduces on devices without a camera. I've attached about:webrtc and a wireshark capture for the case where Chrome is already in the room and Firefox joins. If Firefox is already in the room and Chrome joins, I don't even see a setRemoteDescription.

Comment 6

[Dan Minor [:dminor]]

Byron suspects that Chrome is having problems with the SDP we're generating in this case. I'm having a look.

Comment 7

[Dan Minor [:dminor]]

Attachment: Bug 1646092 - Do not add ssrc-group to sdp on recvonly msections; r=bwc!

Chrome will not accept sdp with ssrc-group:FID on recvonly msections, causing
calls to fail to be established between Firefox and Chrome when only a
microphone is present on the Firefox side.

Comment 8

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/35dcd6ad89c6
Do not add ssrc-group to sdp on recvonly msections; r=bwc

Comment 9

[Dorel Luca [:dluca]]

Backed out changeset 35dcd6ad89c6 (bug 1646092) for Gtests failures in JsepSessionTest.OfferAnswerRecvOnlyLines. CLOSED TREE

Log:
https://treeherder.mozilla.org/logviewer.html#/jobs?job_id=306815628&repo=autoland&lineNumber=9027

Push with failures:
https://treeherder.mozilla.org/#/jobs?repo=autoland&group_state=expanded&revision=35dcd6ad89c69a786c476f541889cbbaee1c4c64

Backout:
https://hg.mozilla.org/integration/autoland/rev/8c4cdaa64649851067def67b1a1d606ff6666d2a

Comment 10

[Dan Minor [:dminor]]

Sorry, forgot to run the gtests locally before pushing this. Try job here: https://treeherder.mozilla.org/#/jobs?repo=try&revision=02b5ed13aa09de4d4ff78610e606047dad03d5eb.

Comment 11

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/1600f8f780e4
Do not add ssrc-group to sdp on recvonly msections; r=bwc

Comment 12

[Narcis Beleuzu [:NarcisB]]

https://hg.mozilla.org/mozilla-central/rev/1600f8f780e4