For me, starting late Tuesday, I see a large build of latency on webrtc calls using Firefox Nightly. I'm using MacOS. This was not a problem last week. I am experiencing this on every call.

13:46.18 INFO: Narrowed inbound regression window from [db88252d, 88e7018a] (3 builds) to [db88252d, 213c2c20] (2 builds) (~1 steps left) 13:46.18 INFO: No more inbound revisions, bisection finished. 13:46.18 INFO: Last good revision: db88252d490fec2c67c0051172419b46e03cf9ee 13:46.18 INFO: First bad revision: 213c2c200c08bee1cb84eb17a1b0ccb92dbb923c 13:46.18 INFO: Pushlog: https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=db88252d490fec2c67c0051172419b46e03cf9ee&tochange=213c2c200c08bee1cb84eb17a1b0ccb92dbb923c Bug 1388219 - down scale camera output frame to the target capability. r=ji

Fixed by backout. https://hg.mozilla.org/mozilla-central/rev/91fc3a79606b

For Munro's benefit, it didn't reproduce for me in a local-loop (same machine) call; it had to be from a different machine apparently, so here's how I reproed it (using my phone as machine #2): STRs: 1. Using a headset on my android phone, open https://appear.in/some-room on 57 fennec and share cam+mic 2. Click the mute icon in appear.in so audio only goes one way. 3. Then on the target desktop machine, open https://appear.in/some-room in Nightly, share cam+mic, and talk Expected result: I hear myself in the headset without delay. Actual result: I hear myself in the headset on a 1-2 second delay.