All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=765579

(For debugging:) Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?sid=1ed060120da22465f43f13a1485211ee8597e0bc5e4a5b44d8f1e7ba7bd8c4bd


Bot(s) for this bug's original alert(s):

chromium-webrtc-rel-mac

I haven't worked with this test at all

Uh oh, that means that WebRTC is outputting almost pure noise on Mac! It's on the FYI bot, which means a WebRTC change could be suspect, but the WebRTC hash doesn't appear to change. Next step is to compare against the pure chromium bots...

Both changes come in at the same time, so it's not because of a webrtc.org change... https://chromeperf.appspot.com/report?sid=3b750bbd5c93f87267ebee85bd3674a8e0403e417497bc13eb48a90a768b1bd8

No obvious culprits in the changelogs (I looked for "audio", "webrtc", "mac").

The FYI bot and regular bot are different machines (build107-b1 and build108-b1), so it seems very unlikely to be a machine error or config error.

The errors happen on the same bot, so it's not due to a machine switch...

I tried downloading a recent enough canary and WebRTC audio doesn not seem to be completely broken as the test would indicate. I can't find anything that could explain this. It's not urgent so therefore downgrading priority. I guess I'll have to build the test on mac and see if we can get it working again...

The test works just fine locally, audio is loud and clear, so I guess something is wrong with this particular bot.

Or bots, actually, since it hit both bots at the same time.

Managed to log into the bot now and it's correctly configured. 

henrik reports the machine is 3,5 yrs old.

All graphs have recovered, for some reason. I'm marking this as fixed.

That's good news, but also very annoying. I really don't understand what happened here. Edward, did you do anything to the chromium FYI bots on Oct 2?

Nope

I agree it's annoying. I would estimate that a solid majority of the perf issues I triage end up in the "inexplicable" bucket.