Have you ever wondered just how “live” the broadcasts really are? When we watch live streaming at home, we don’t usually observe the real, down-to-the-second events, but their version with a few seconds delay. This is called video latency or the moment between the video being captured by a camera until the moment it is displayed on the viewers’ screen.
The progress of technological innovations and various streaming protocols have made it possible for this streaming delay to be drastically reduced. This comes as a crucial factor for many industries which often broadcast events like conferences, concerts, games or tutorials online.
Today we take a closer look at how latency works and particularly at low latency for video streaming - why it is important and how to make sure your hosting provider offers you the best streaming protocols tailored to your needs.
What is video streaming latency and how does it work
When you’re watching a live stream, you actually see everything on your screen with a delay ‒ it might not be significant, but it usually exists. Sometimes it can be up to 30 seconds ‒ it depends on the streaming quality, amount of data transferred, and the speed of the connection. The delay we’re talking about is called latency, and the main thing you need to know about it ‒ the lower, the better.
As mentioned above, latency states for the time spent for a video “to travel” from a capturing device to the viewer’s screen. There are a few types of latency: a server and a client. The server latency describes the time the data needs to pass from a sender to a server, and the client’s latency is basically a local latency, describing the time the data needs to be processed in the viewer’s device.
What is considered “normal” latency then?
For regular videos like streaming movies, five seconds latency is standart. Of course, it all depends on the streaming technology, so it’s important to research in advance what protocols your streaming provider offers and supports.
What is considered “normal” or regular frequency for live events like the one above, can sometimes be too long for other.
For example - in educational online courses, conferences and other online events where interactive content is involved low latency is a must.
Streaming protocols providing low latency
We’ll start with the standard latency protocols moving to low latency protocols providing near real-time streaming. You can view it as a graphic timeline ‒ the closer to the end, the shorter the glass-to-glass latency is.
Some protocols like Apple HLS and MPEG-DASH provide latency between 30 up to 45 seconds. Apple HLS and MPEG-DASH are suitable for regular live streams. DASH and HLS protocols are HTTP-based, but with MPEG-DASH you get the opportunity to work with any codec and implement a playback, while HLS is perfect for almost all devices and browsers. Let’s dive deep into low latency protocols and the improved versions of the two above mentioned technologies: LL-HLS and LL-DASH.
LL-HLS and LL-DASH
LL-HLS stands for Low-Latency HTTP Live Streaming, providing low-latency video delivery. Usually it provides latency up to 2 seconds, which is a good solution for most live streaming formats, like interactive educational videos, Q&A sessions or conferences.
LL-DASH stands for Low-Latency Dynamic Adaptive Streaming over HTTP. It’s a variant of MPEG live streaming serving as an alternative to HTTP streaming. This technology is more recent ‒ it was founded in 2017 ‒ but it has already shown good results in low latency streaming. LL-DASH is stable technology; one of the downsides, however, is that it does not support playback on Apple devices, unlike the HLS.
WebRTC (near real-time streaming protocol)
WebRTC is a HTML5-based live streaming open-source technology providing users with extremely low sub-second latency. WebRTC is easy to use, and the technology is perfect for browser-based video delivery. The latency can be as low as 0.5s, allowing to stream various types of videos.
How to choose
What becomes clear is that low latency, and especially near real-time streaming, is crucial for businesses that often stream, like media organizations or e-learning solutions.
Depending on what your goals are, for most businesses the popular low latency protocols included in the article will provide a smooth livestream experience. Nowadays modern video streaming solutions are equipped with most new low latency technologies to help you deliver a seamless streaming experience.
At Kinescope we use advanced streaming protocols, such as HLS, DASH, LL-HLS, WebRTC combined with network stack tuning to drastically reduce latency. Furthermore, all live streams hosted on Kinescope are accelerated with our private CDN, perfect for large volumes of video traffic.
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