Video Live Streaming: Notes on RTMP, HLS, and WebRTC • Hacker News Board

Re: Video Live Streaming: Notes on RTMP, HLS, and WebRTC

#81

Post by difosfor » Wed, Jun 08, 2022, 12:30 AM UTC

GOATS- wrote: post #79

difosfor wrote: post #52

We're using DASH and experimenting with LL-HLS to get reliable and affordable (using CDNS) end to end latency of 3 seconds with which you can already interact live with your audience without too much trouble. Latencies down to about 1 second are also feasible already at the cost of some client side buffering. So I would have expected to see more information about DASH than HLS here. It's usable on all platforms excep…

Have you tried LL-DASH? It's somewhat more available for usage in tools like ffmpeg. I'm looking to experiment more with it on my own streaming platform. https://github.com/GOATS2K/overpass

I wasn't aware of that name yet, but yes, we're using chunked transfer etc. to reduce the latency.

Re: Video Live Streaming: Notes on RTMP, HLS, and WebRTC

#82

Post by difosfor » Wed, Jun 08, 2022, 12:50 AM UTC

rollcat wrote: post #74

difosfor wrote: post #52

We're using DASH and experimenting with LL-HLS to get reliable and affordable (using CDNS) end to end latency of 3 seconds with which you can already interact live with your audience without too much trouble. Latencies down to about 1 second are also feasible already at the cost of some client side buffering. So I would have expected to see more information about DASH than HLS here. It's usable on all platforms excep…

> It's usable on all platforms except iPhones and Apple TV where we're forced to use HLS at higher Latencies for now and hopefully later also DASH or LL-HLS once that's reliably usable. Interesting, since it was Apple who designed & built both the original HLS and the LL extensions. What's currently preventing LL from being usable there?

Their initially released specification depended on some relatively impractical services being provided by the CDN. In following revisions that was improved, but last I checked the major CDNs still didn't support it. I think because it still requires much more from the server side than DASH and struggles to reach comparably low latencies. In the mean time people like us have started to work around it to get DASH support in iOS instead.

Re: Video Live Streaming: Notes on RTMP, HLS, and WebRTC

#83

Post by difosfor » Wed, Jun 08, 2022, 1:14 AM UTC

kwindla wrote: post #64

difosfor wrote: post #52

We're using DASH and experimenting with LL-HLS to get reliable and affordable (using CDNS) end to end latency of 3 seconds with which you can already interact live with your audience without too much trouble. Latencies down to about 1 second are also feasible already at the cost of some client side buffering. So I would have expected to see more information about DASH than HLS here. It's usable on all platforms excep…

Nice! I am a bit skeptical about "down to about 1 second" being achievable with DASH or LL-HLS reliably. Of course, I could be wrong. And a lot depends on the definitions of "about" and "reliably," as well as your user cohort (where they are in the world, etc). :-) The reason I didn't write much about DASH is that the basic concepts are the same for both DASH and HLS. And my sense for the last couple of years has bee…

In some areas of the world where network and/or device performance are limited such a low latency will be impossible to achieve indeed. Inter regional broadcasting also comes with a latency penalty, but with good CDNs like provided by our partner Akamai you can already get a 1 second latency in many cases. That being said the buffers will be very small and we don't recommend using that yet in general.

HLS and DASH are similar indeed, but I think the main reason that HLS is still used a lot is that it's the lowest common denominator; you can get it to work everywhere. Perhaps in the future that will be LL-HLS, or something else entirely, but for now most really low latency broadcasting that I'm aware of is using DASH with HLS as a fallback (i.e: CMAF). But I could also be wrong about that of course :-)

Re: Video Live Streaming: Notes on RTMP, HLS, and WebRTC

#84

Post by Nasreddin_Hodja » Wed, Jun 08, 2022, 9:32 PM UTC

fiestajetsam wrote: post #4

WebRTC is not the future of low latency live streaming... at least not outside of video conferencing. It's incredibly complex as a specification, has limitations and numerous issues that set limits in how scalable it can be. Conversely, for HTTP segment based formats like HLS and DASH have limits due to their design (and that of HTTP) which set how low latency can actually go. Where's the future? A likely candidate m…

I'd like to see native RTSP support in browsers. WebRTC is based on it, I see no reason why it is ignored.