Game, set and match to HDR

In the past couple of years, the sports broadcast sector has embraced the challenge of 4K UHD. In the UK, we have seen large-scale investment in 4K trucks to realise the ambition of broadcasters to offer 4K sports coverage at a premium.

4K is, at its most basic, just a load more pixels, and the challenge for everyone is that 4K effectively uses four of everything where we used to use only one. This turns into a very uncomfortable uplift in the bandwidth budget for production, storage and distribution. Things gets even worse when scale is brought into play.

At ATP Media, the broadcast and media arm of the ATP World Tour, we have been exploring the pros and cons of 4K. Covering more than 1,200 tennis matches every year at 23 tournaments around the world, we must carefully understand the impact of a move to 4K production and delivery to a global audience.

What would we get for our 4K efforts? I’m not sure I see the benefit. The average size of a TV screen sold nowadays is around 49 inches in Europe and 52 inches in the US. Under normal viewing conditions, and at the distance we would normally sit, 4K pixels don’t deliver a significant improvement in viewer experience on screens of this size.

If we want to really appreciate the difference of 4K over HD, we should be watching on screens that are at least 75 inches.

The problem with very large screens is the bigger they are, the further moving things like a ball have to travel for each frame. In fast sports action, we face the consequence of requiring high frame rate (100/120 fps), which blows our bandwidth budget even further.

Don’t get me wrong, I am a massive fan of high-resolution acquisition, and 4K sensors in cameras are an essential ingredient of this. But maybe there is a bigger bang for our buck in other corners of the UHD Aladdin’s Cave.

The biggest visual bang for a consumer undoubtedly comes from Wide Colour Gamut (WCG) and High Dynamic Range (HDR). It is quality of pixels that counts, not quantity.

As a sport that is played on such a wide variety of stages, from theatrically lit indoor tournaments to outdoor, desert sun and tropical weather, it is clear that HDR (including WCG) makes the biggest difference to the viewing experience.

Thus, if we use 4K cameras for acquisition, and take advantage of being in a progressive 50fps or 60fps world rather than an interlace format, then we can produce and easily distribute a high-quality 1080p HDR feed to our broadcasters, who can upscale if required for 4K HDR services.

For a global travelling sport like tennis, it means we can look to start producing in HDR much earlier than if we had to wait for the time when all the payload issues of 4K have been resolved.

At the Nitto ATP Finals last November, we did a side-by-side test of 1080p50 HDR with 4K HDR on 55-inch screens and the average viewer could not tell the difference, but they were universally bowled over by the HDR.

Shane Warden is director of broadcast and technology at ATP Media