Latency

So based on my tests (1080p70 @ 12000kbps), using SRT input and HLS out has a delay of 45 seconds. Using SRT input with dash gets a delay of 22 seconds. But the problem with webrtc is the input needs to be webrtc too which tools like OBS can't

Brendan Irvine-Broque•10/7/22, 10:08 PM

Thanks for sharing what you're seeing, especially the difference between HLS and DASH. We're doing a bunch of work right now on latency and this is helpful.

If you're looking to reduce latency a bit further using RTMP or SRT, try changing the GOP duration in OBS to 2 seconds
For sub-second latency, yep, you'll need to use WebRTC for both broadcasting and playback. There's active discussion on adding WHIP support to OBS here: https://github.com/obsproject/obs-studio/pull/7192

GitHub

obs-webrtc: prototype / playground by DDRBoxman · Pull Request #719...

Description

This draft PR shows off some work on how we could structure a webrtc plugin without needing to pull in the large monster that is libwebrtc. It provides the webrtc output in such a way...

Brendan Irvine-Broque•10/7/22, 10:08 PM

Curious — what are you trying to build?

VictorOP•10/7/22, 10:16 PM

For GOP, you are referring to keyframe interval right? These are the settings (obs side) that I'm using for the test. Using the exact same settings on twitch (except bitrate lowered to their max of and fps lowered to their max of ) gets a 3 second delay

BBrendan Irvine-Broque Curious — what are you trying to build?

VictorOP•10/7/22, 10:17 PM

Basically I'm trying to build a decentralized streaming service that's completely FaaS with D1/DO as storage

Brendan Irvine-Broque•10/7/22, 10:24 PM

Yep — keyframe interval.

One thing to note — when you stream to Twitch, unless you're a Twitch partner, Twitch does not re-encode your live stream to make it available at multiple quality levels. Stream does this, to ensure that the stream can be viewed even if the viewer doesn't have enough bandwidth for, say, a high bitrate 1080p stream.

We also do a few things behind the scenes to ensure that as more people watch a live stream, latency is reduced. What you're seeing as the first and only viewer for the live stream has a bit higher latency than subsequent viewers.

All that said, still higher latency than is typical, and higher than we're aiming for. Expect more updates soon on cutting this down further. I'll shoot you a note.

BBrendan Irvine-Broque Yep — keyframe interval. One thing to note — when you stream to Twitch, unless ...

VictorOP•10/7/22, 10:30 PM

I wonder if there is a possibility where you could add an "original" quality settings (like above the 1080p option for example in your own player) where you (if the end viewer has the bandwidth) can view it without re-encoding.

VVictor I wonder if there is a possibility where you could add an "original" quality set...

Isaac McFadyen•10/7/22, 10:46 PM

The main thing with this is that the re-encode to HLS takes time, not necessarily only the re-encode to multiple quality levels.

Isaac McFadyen•10/7/22, 10:47 PM

(although they both take time)