IETF Incorporates Low-Latency HLS Into the HLS Spec

IETF Incorporates Low-Latency HLS Into the HLS Spec

In HTTP Live Streaming (HLS) 2nd Edition, published by the Internet Engineering Task Force (IETF) last week, Apple’s Roger Pantos announced that Low-Latency HLS and HLS are no longer two separate streaming protocols. Rather, the Low-Latency HLS extension has been baked into the HLS specification as a feature set.

What does this mean and how will it impact the streaming industry? Let’s take a closer look. 


HLS vs. Low-Latency HLS

Before diving in, it helps to clarify the basics. So, what is HLS and how did it relate to Low-Latency HLS prior to this development?



HLS, which stands for HTTP Live Streaming, is the most common streaming protocol in use today. Apple designed the protocol to transfer streams of live and on-demand streaming content to Apple devices, but today it’s supported by all Microsoft, Android, and Linux devices. HLS leverages HTTP technology for scalability and adaptive bitrate streaming for high-quality viewing experiences. 


Low-Latency HLS

Low-Latency HLS is an extension to the HLS protocol developed to deliver the same simplicity scalability, and quality as HLS — while also reducing latency to less than two seconds. Roger Pantos first announced the spec at the 2019 Worldwide Developer Conference (WWDC). In the year that’s followed, vendors across the industry have worked to add support, and Apple has made several updates to help streamline adoption.


The Impact of Incorporating Low-Latency HLS Into HLS

HLS and Low-Latency HLS have always been closely linked. But while HLS is a tried-and-true protocol used ubiquitously for streaming, Low-Latency HLS has only been around for a year, during which time its requirements and usability have remained in flux.

We added support for Low-Latency HLS in Wowza Streaming Engine at the end of last year. However, large-scale deployments of Low-Latency HLS have remained aspirational. That’s because an end-to-end workflow requires integration with CDNs and players, and many vendors are still working to add support for the emerging spec.

With last week’s update, Apple has incorporated the next-generation Low-Latency HLS extension into traditional HLS. The significance of this is twofold: it further standardizes the spec and puts pressure on technology providers to add support. 



HLS is the mainstream protocol for streaming video distribution today. And it now offers the ability to deliver sub-two-second video streams at scale as part of the overarching standard. 

By adding the Low-Latency HLS feature set to the core HLS specification, Apple and the IETF will drive greater adoption of this technology.


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About Traci Ruether

Traci Ruether is a Colorado-based B2B tech writer with a background in streaming and network infrastructure. Aside from writing, Traci enjoys cooking, gardening, and spending quality time with her kith and kin. Follow her on LinkedIn at or learn more at