How live is live? Just had a >15min during a 1hr live

I just streamed https://video.benetou.fr/videos/watch/37679db0-750d-40c1-b76c-67bad6c0207b and it went well, no technical glitch and as you can see the transcoding is already online.

That being said when I pressed « Stop streaming » on OBS I went back to check where the stream was, if it was slightly behind e.g. 15sec or not. I was quite surprised to notice it was not just a bit behind but minutes, at least 5min but I would say a lot more than that.

I didn’t have the time during the live session to check stats on the server but what could cause than and what can I do to have e.g. 15sec delay to allow for live chat?

I ran another test this time without OBS, just ffmpeg with my webcam while insuring the server wasn’t the issue (0.25 server load, no swapping or other weird on-going background tasks according to top).

What was strange was that the bit of delay was different on my desktop and mobile. Meaning on my mobile I had maybe 15seconds delay on live but on my desktop maybe 25sec. How is that possible?

I was able to check top during the event this time and … well yes clearly there is a performance issue. I’ll try again with a larger instance. Sadly this isn’t a scalable one so I’ll have to migrate first then try again.