Slack is an über popular and fast growing communications tool that has a ton of integrations with various WebRTC services. Slack acquired a WebRTC company a year ago and launched its own audio conferencing service earlier this year which we analyzed here and here. Earlier this week they launched video. Does this work the same? Are there any tricks we can learn from their implementation? Long time WebRTC expert and webrtcHacks guest author Gustavo Garica takes a deeper dive into Slack’s new video conferencing feature below to see what’s going on under the hood.
webrtcH4cKS: ~ Is Slack’s WebRTC Really Slacking? (Yoshimasa Iwase)
Earlier this month Fippo published a post analyzing Slack’s new WebRTC implementation. He did not have direct access or a team account to do a thorough deep dive – not to mention he is supposed to be taking some off this month. That left many with some open questions? Is there more to the TURN network? How does multi-party calling work? How exactly is Slack using the Janus gateway? Fortunately WebRTC has an awesomely active and capable community that quickly picked up the slack (pun intended).
webrtcH4cKS: ~ Dear Slack: why is your WebRTC so weak?
There has been quite some buzz this week about you and WebRTC.
WebRTC… kind of. Because actually you only do stuff in Chrome and your native apps:
I’ve been there. Launching stuff only for Chrome. That was is late 2012. In 2016, you need to have a very good excuse to launch something with WebRTC and not support Firefox like this:
Maybe you had your reasons. As usual, I tried to get a dump from chrome://webrtc-internals to see what is going on. Thanks to Dag-Inge Aas for providing one. The most interesting bit is the call to setRemoteDescription:
type: answer, sdp: v=0
o=- 1242503183783 1242503183783 IN IP4 127.0.0.1
s=Room with no name..
a=msid-semantic: WMS janus
m=audio 1 RTP/SAVPF 111
c=IN IP4 10.9.4.95
a=fmtp:111 minptime=10; useinbandfec=1; usedtx=1
a=candidate:1 1 udp 2013266431 10.9.4.95 12000 typ host
a=candidate:2 1 udp 2013266431 172.31.0.190 12000 typ host
I would like to note that you reply to Chrome’s offer of UDP/TLS/RTP/SAVPF with a profile of RTP/SAVPF. While that is still tolerated by browsers, it is improper.
Your a=msid-semantic line looks very interesting. “WMS janus”. Sounds familiar, this is meetecho’s janus gateway (see Lorenzo’s post on gateways here). Which by the way works fine with Firefox from what I hear.