Video: Do You Really Need Low-Latency Streaming?
While low latency is a goal for all live streaming applications, commonly associated with reliability and a better user experience, reducing latency also increases the expense of delivering large-scale streams. In this excerpt from his presentation at Streaming Media East 2017, Wowza VP of Product and User Experience Mike Talvensaari argues that low latency isn't always worth it, and that you should prioritize it only in certain use cases.
Learn more about low-latency streaming at Streaming Media West.
Mike Talvensaari: We hear terms like low latency, ultra-low latency, real time. What do we really mean when we talk about these things? So I'm going to start at the left combination for the latencies for HLS and DASH. These are upwards of 45 seconds, 30-45 seconds depending in you're going through a CDN. And this is for one way streams to large audiences. I have to have massive scale, people want to see it in HD, or 4K. And so I can deal with latency there. Reduced latency is kind of 5 to 20 seconds. 2-18 seconds. And this would be live streaming of news, sports, and content for OTT providers.
Low latency. 5-7 seconds is typical latency for HD cable TV. And so we call low latency anything faster than that. And this is for live streams, game streaming, E-sports--sometimes you want to try to match that 5-second delay if you're streaming television content. So it matches up with what people are seeing if they're watching on TV. You want to be shouting “Goal!” at the same time as your neighbor if you're watching a sporting event.
And the near-real time is sub-1 second. So this would be for real-time communications, conferencing, any sort of telepresence, real-time device control. I'm controlling a PTZ camera, I want to hit the button and see it pan right immediately. So that's near-real time. That's some definitions.
People think they need really low latency streaming all the time but they don't necessarily need it. So in designing your system, if you want low latency, it's just going to cost more. You're going to have to buy more expensive devices. You're going to have to have more servers. Higher quality, higher bandwidth. But you often don't need lower latency. A 30-second delay is not often a problem.
So latency doesn't actually matter. So really think about, do I need low latency? Does my use case need low latency? If I'm streaming high school sports, does it really matter if grandma in California sees it 30 seconds delayed or not? Probably doesn't matter.
HTTP streaming, which is the most popular format for streaming now, intentionally introduces latency for improved reliability. So Apple HLS and MPEG-DASH, both by default out of the box require three chunks to be loaded. The chunks are 10 seconds, that gives you a huge buffer of time for network hiccups. Buffering has been greatly reduced over the years due to things ... like this. And so, reliability has improved with some of these things.
For some live streams latency is critical. If you're doing rea- time communication, it's critical. Anything over a second is painful. If you're doing online gaming, any sort of remote control devices ... gambling, auctions, latency is critical for certain use cases.
Sometimes low latency is critical, but in other streaming applications it's not worth prioritizing, Wowza Senior Solutions Engineer Tim Dougherty argues in this clip from Streaming Media West 2018.
Wowza Media Systems Senior Solutions Engineer Tim Dougherty surveys the recent and current state of streaming latency in this clip from his presentation at Streaming Media West 2018.
Limelight's Charlie Kraus discusses three emerging strategies for delivering low-latency live streaming in the post-Flash era.
Haivision CTO Mahmoud Al-Daccak discusses the challenges of delivering low-latency streams across unmanaged networks in varying use cases at Streaming Media West 2017.
Streaming Video Alliance's Jason Thibeault and Limelight's Charley Thomas address the question of whether WebRTC provides a viable solution for network latency issues in this panel from Live Streaming Summit.
StackPath's Nathan Moore explains the protocols, latency, and bandwidth challenges inherent to delivering video content to iOS devices and how content providers can stream to these devices more effectively.
Yahoo Director of Engineering Satender Saroha discusses latency issues particular to VR streaming to mobile and technical measures to address them.
Wowza Senior Product Manager Jamie Sherry discusses key latency considerations and ways to address them at every stage in the content creation and delivery workflow.
The report, "Create the Streaming Media Experience Users Want," focuses on time to first frame and end-to-end latency in five markets: user-generated content, online gaming, sports, news, and radio.
Reel Solver's Tim Siglin, Rainbow Broadband's Russ Ham, and Verizon's Daniel Sanders discuss how attacks on Net Neutrality would impact video delivery in general and latency in particular.
Wowza's Tim Dougherty and Streaming Media's Tim Siglin discuss how Wowza is meeting the challenges of keeping latency down for live video with its Streaming Cloud in this interview from Streaming Media East 2017.
Ooyala's Paula Minardi and Level 3's Jon Alexander discuss the key issues facing live streaming and VOD providers regarding latency times, buffering, and meeting evolving viewer expectations.
It's one of the biggest challenges facing live video streaming today, and it's remained frustratingly stubborn. Explore the technical solutions that could finally bring latency down to the 1-second mark.
Ensuring broadcast quality for viewers is about more than just reducing buffering. Publishers need to improve the efficiency of back-end operations, as well.
The upcoming third edition of DASH will address several missing features, says a Comcast principal architect, and will drive down live video latency.
Companies and Suppliers Mentioned