Occasional dropouts from host during call

[spacehobo]

I just sent a 5m recording of a test session I made with a co-host of a podcast I'm on (semi-privately, via mastodon), and found that the first few sentences from my side got oddly clipped out in places. It smoothed out as the session continued, but then picked up occasionally. I'm on a Sennheiser Profile USB mic with headphones in the monitor port live mixing with all computer audio output, and didn't hear any peaking or dropout in the monitor feed.

I've also noticed this on a Distributed Future episode from 2022 (the one about "will we regret computing the way we do cars in cities"), and wonder if perhaps the browser settings need to be tweaked to turn off echo cancellation entirely.

[steely-glint]

I've had a listen to the sample you sent, and yep there is an audible hole at the 5.5 second mark. I'm not sure what caused this, but at a guess I'd say you changed the window or tab stacking order in the browser. Given we make the recording in javascript it can be sensitive to what else is happening in the browser.

I've also listened to the DF episode you mentioned - I can hear what you describe in the MP3 - but not in the original webM. So I suspect the problem is in the decode/re-encode from webm to ogg or mp3 . It is possible that the blocks are occasionally stored out-of-order in the webm and this confuses the re-encoding process (ffmpeg in my case).

I'll look at moving the recording process to a web-worker to make it more resilient to browser upsets.

As I said on mastodon, we allow the browser to make its own decisions about echo cancelling, in general this gives us decent audio with the minimum of setup time. It would be possible to add controls for this - but the defaults are pretty good - especially on modern phones.

[spacehobo]

Ah, this does make sense, as I think I had backgrounded the browser window (which was only open to the podcall page and nothing else: I use Firefox for my normal browsing, so it was a solo Chromium window). When I heard my friend's voice, I Alt+TABbed to it to make sure it was all showing what I expected. That seems a simple enough operational note to work with, anyway: just leave the browser window alone or arrange moments of non-recorded audio when changing the window stacking.

Interesting about the transcoding artefacts! I'll have to watch out for that on a project I'm working on, but I was probably going to use lame for that. I wonder if there are ffmpeg options that could have untangled the stream.