Losing the lag: Why sports streaming is one of the biggest victims of delay

Latency is the time it takes for live content to travel from its source to its destination. This can vary widely, though estimates suggest that delays are typically around 15-30 seconds for online content, while broadcast television is under ten seconds. Unsurprisingly, latency in sports is somewhat of an issue.

Audiences watching Euro 2024 last summer might have noticed that familiar frustration we’ve so often seen when livestreaming football: goal notifications lighting up phones before the ball even hits the net on screen. Viewers might also have tuned in to the highly anticipated Mike Tyson vs Jake Paul boxing match, streamed live on Netflix, only to experience significant buffering issues. The wide array of options and platforms for consuming live sports doesn’t come without its difficulties for broadcasters.

As more people stream live sports, latency issues have become more frequent and noticeable, leaving viewers frustrated. The gap between action happening and when viewers actually see it on screen can vary wildly, depending on the platform, device or even event itself. Broadcasters and streamers work tirelessly to tackle these issues, which is no small feat.

The BBC, for example, recently trialled its first phase of low-latency live streaming on iPlayer. This trial helped the BBC assess how well low-latency streaming approaches perform over today’s internet and into viewers’ homes. Sky Glass and Stream users usually witness a goal much later than their satellite-using counterparts. That all changed this summer when a new low-latency version of Sky Sports Main Event was launched, which successfully reduced lag by 20 seconds.

Ultra-low latency technology

Haivision are committed to tackling key areas in latency. Its Pro 460 mobile video transmitter, for example, features ultra-low latency mode when transmitting over 5G networks, bringing latency down to as low as 70ms between camera and production. Haivision’s mobile video transmitters are designed for low-latency, reliable live video contribution over bonded cellular and IP networks from anywhere and are an ideal solution for sports broadcasting.

Mark Horchler, marketing director at Haivision, explains that the company are always focused on making sure their broadcast customers – especially sports broadcasters – can work with as low a latency as possible, whether it’s over internet or over 5G (including private) networks. “We’re bringing that latency lower and lower every time” he explains. “At IBC this year, we demonstrated how we can provide under 80ms of latency over private 5G networks for live sports.”

“We’re always looking to reduce latency even further,” Horchler continues. “We’re looking at things such as slice base capture, to lower latency even further by encoding videos per slice instead of per frame. That’s one technique we’re using, and applying the latest 5G technology as well, to reduce latency that way. We’re always looking at ways to reduce latency while keeping picture quality pristine.”

Matching latencies between viewers

Bitmovin are also making strides in tackling these issues, and have aimed to reduce live stream latency from 30 down to five seconds. The Bitmovin Player supports low-latency playback of live streams in multiple formats and provides a target latency feature too.

Senior director of product management at Bitmovin James Varndell explains that when it comes to varying latency issues across different sporting events, scale is a consideration. “If you’re streaming with low latency for small sporting events then you might be able to use very low-latency technologies, but they might not be scalable in a cost-effective way for the biggest global events. For example, we see occasional use of technologies like Web RTC to achieve sub-three-second latency for small events or in-stadium streaming (eg. horse racing) but it’s challenging to scale those to globally watched events like the Super Bowl. For larger events, HLS or DASH streaming is still the preferred approach in the industry; formats like LL-HLS & LL-DASH using CMAF can lower latency for large events and global streaming to most devices.”

According to Varndell, the nature of different sports and different regions can also influence latency. “For example, some of the use cases for ultra-low-latency streaming can be related to real-time gaming and betting,” he explains. “Again, this might lend itself more towards sports where gaming and betting are more common (eg. horse racing). In some countries or states, betting might be banned or the individual sport might not allow betting. In those cases, low latency is still important for viewer experience and interactivity, but betting isn’t there as a business driver.”

In terms of next steps for improving live-stream delays, wider rollout of CMAF-based low-latency streaming with LL-HLS or LL-DASH is one of the options. “Many OTT services streaming live events are using standard HLS or DASH and achieving latencies of around 30 seconds,” explains Varndell. “CMAF-based LL-HLS and LL-DASH are deployed by some streaming services, but it isn’t the norm. These technologies are highly compatible with most devices and can reduce latencies to between four and eight seconds.”

Varndell points to one common misconception, which is that it’s all about reducing to the lowest latency possible. “The difference in latencies across everyone streaming the same live event is also important,” he says. “If you have a large difference between viewers, this can negatively impact the experience. For example, if some viewers are watching with a latency of six seconds, while others have a latency of 50 seconds, then in second screen experiences like chat features within the live event, the audience won’t all be seeing the same content at the same time. This issue can be solved by configuring a target latency into video players, such as the Bitmovin Player, to keep all viewers in sync.”

Bridging the gap

AJA are one of a number of companies at the forefront of tackling latency issues in live sports broadcasting. Connecting sports fans with live games via streaming services relies on technologies that reduce latency to an absolute minimum. “Multiple feeds from the same games must also remain in sync, so it’s vital for production teams to be able to adjust latency relative to each individual stream where necessary,” says Andy Bellamy, technical director (EMEA) at AJA. “AJA produces the ultra-reliable Bridge Live line of products, which provide functionality and control, shortening the time taken for action of big games to reach viewers outside the stadium or arena to mere milliseconds. Ensuring low-latency performance for inline colour transforms and HDR in live sports productions is also increasingly paramount, which is where technologies like AJA’s Color Box are beneficial, providing less than half a video line of delay.”

Newer video compression technologies, like JPEG XS, bring extremely low latency even over public internet, while remaining visually lossless in terms of image quality. “Our Bridge products all feature an option to add JPEG XS and JPEG 2000 to workflows that require the lowest possible latency but the highest visual quality,” says Bellamy. “AJA remains fully committed to finding more innovative ways to lower latency in streaming workflows, bringing flexible options to it professional IP streaming products.”

Latency remains one of the biggest challenges in live sports broadcasting. Network infrastructure is critical to ensure minimal delays. Even the smallest of delays can be off-putting enough for viewers to switch to another channel, leading to lost revenue for broadcasters. Any lag in a live game can be enough to ruin an experience, as readers will be well aware of. Typically, higher latency has resulted in better picture quality. However, this isn’t enough of a draw for viewers to put up with not being up to date with the action. There are other means of achieving and maintaining high picture quality without compromising on latency improvements.

The way we consume live sports is continually changing, with significantly more platforms for viewing content. It is paramount that continued developments in technology keep up with the demand for low-latency solutions. 5G networks, ultra-low-latency streaming platforms and AI-driven optimisation are just a few of the many ways to achieve a better viewing experience.

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