11.12.17

Are you game? Meeting the demands of modern-day gaming in the smart home

Example of frame tear, indicating a refresh rate conflict. (Source Reddit.com Fallout 4 forum, © Bethesda Game Studios)
Example of frame tear indicating a refresh rate conflict (Source Reddit.com Fallout 4 forum, Bethesda Game Studios)

Gaming in 2018 is all about immersion — 4K resolution, greater colour volume with high dynamic range (HDR), all augmented by immersive audio. Sound familiar? We’ve already been talking about these same things with video content, but gaming adds even higher performance demands and more installation challenges; an important consideration if gaming is part of your next project.

Gaming demands speed. It must be FAST! Mere milliseconds of latency can be the difference between life and death in the virtual world, while things like frame tear are just plain annoying. Gaming also has a far more compelling use case for high frame rates than even movies. So how do you deliver exceptional gaming performance for your clients?

There are three key considerations: network connectivity, video bandwidth, and settings.

Network Connectivity

Wired is best. Wireless connectivity can create what online gamers frustratingly refer to as a “laggy” experience. The reason is that Wi-Fi is half-duplex, meaning it communicates in only one direction at a time. Online gaming requires constant sending and receiving of data in real time, but if send and receive data has to take turns, things can lag.

A wired network is full duplex, capable of simultaneous bi-directional communications. Graphics data is not being sent over the Internet, only actions and orientation data, so there’s not a big bandwidth load. As such, Internet connection speed is surprisingly not as critical as a full-duplex connection to the router to ensure unhindered, real-time response. Having said that, faster is always better! Of course, the gaming console or computer must be up to the task on the graphics side of things too.

Video Bandwidth

For gaming, 4K/60 with HDR is a whole LOT of high quality pixels to render in every frame, in real time. That needs serious horsepower. As an example, Microsoft’s new Xbox One X (aka Scorpio) sports a blistering six TeraFLOPS of GPU speed and 326 gigabytes per second of memory bandwidth! It’s a very different proposition from merely decompressing content from an UHD Blu-ray disc. However, where the resolution, frame rate and colour are all equivalent, the output amounts to the same load over HDMI. Either way, you need to ensure the connectivity to the display can deliver.

The maximum data rate currently supported by HDMI 2.0 is 18Gbps – consider this a mandatory requirement. Where possible, also cater to an HDMI 2.1 upgrade path with its fixed rate link @48Gbps, enabling future format combinations like 4K 60fps (or higher) with native RGB in combination with 10- or 12-bit HDR (e.g. HDR10 and Dolby Vision respectively), which is beyond HDMI 2.0. We’ll get back to that shortly…

“Where possible, cater to an HDMI 2.1 upgrade path with its fixed rate link @48Gbps, enabling future format combinations like 4K 60fps (or higher) with native RGB in combination with 10- or 12-bit HDR…”

HDMI 2.1 also introduces a new feature called Variable Refresh Rate (VRR) for gaming. This can dynamically change the frame rate depending on the game play. For example, 30fps while leisurely exploring, that instantly steps up to 60 or 90fps as soon as the speed needs a boost to match the adrenalin of engagement with fast, complex graphics. VRR is based on VESA’s Adaptive-sync standard, which has been available on some PCs for a while as AMD’s “Freesync” or Nvidia’s “G-sync.”

As the Video Electronics Standards Association (VESA) advises: “In gaming applications, a computer’s CPU or GPU output frame rate will vary according to the rendering complexity of the image. If a display’s refresh rate and a computer’s render rate are not synchronised, visual artefacts — tearing or stuttering — can be seen by the user.”* Without VRR, moving to a faster refresh rate can lead to the faster frame wanting to resolve before the slower frame has finished changeover, causing frame tear.

Getting back to the Xbox One X, the HDMI output is specified as version 2.0b, meaning it’s limited to 18Gbps. VRR might theoretically be made available via a firmware upgrade, but a change of hardware would be required to increase the bandwidth beyond 18Gbps.

Colour Settings

Gaming renders pixels in full bandwidth native RGB, whereas virtually all video (movie and TV) content available to us is in component video 4:2:0. In short, that means that gaming is heavier on the wire. The challenge here is that while RGB is the best, HDMI 2.0 doesn’t have the bandwidth to support 4K/60 RGB (same as 4:4:4) at anything more than 8-bit colour. HDR needs 10- or 12-bit to achieve the intended colour volume. HDMI 2.1 will resolve this, but until then something’s got to give.

Screen shots from X-box One S, showing setup to support 10-bit per channel (30-bit total) colour, and permission to convert to YCC 422 for 4K60 HDR support

The solution to enable HDR along with 4K/60 gaming is to set the gaming source to employ Colour Space Conversion (CSC). This will take the RGB render and convert it to component video 4:2:2 (or lower), to free up bandwidth that it can then use for deep colour. The result is that 4K/60 12-bit HDR 4:2:2 runs at the same data rate as 4K/60 8-bit RGB, both just under the 18Gbps HDMI 2.0 limit.

Look in the video settings menu of the gaming console to enable component video output (often called YCC), and possibly conversion to 4:2:2 or less, while also enabling Deep Colour and HDR. Keep in mind that 10-bit and 30-bit colour are the same thing, 10 being per channel, 30 being the aggregate of three channels.

Conclusion

Movies and televisions aim to draw the viewer into the narrative. With gaming, it’s about the play environment and response time. Beyond that, they’re actually not dissimilar, with both potentially benefitting greatly from video advances like deep colour, HDR, and far more pixels per second. It’s all about speed — speed of processing, speed of play, and speed of delivery. That means bandwidth.

We trust in the makers of gaming consoles to spin their magic inside the box. It’s our job to ensure we capitalise on this by connecting it properly, both online and to the AV system.

* https://www.vesa.org/news/vesa-adds-adaptive-sync-to-popular-displayport-video-standard/

 

David is a 23-year veteran of the industry, with experience spanning photographics and imaging, home theatre retail and custom installation, then product design, manufacturing, and distribution as founder of the Kordz Group. He’s worked as a CEDIA volunteer for a decade, establishing a reputation as one of the most prolific Subject Matter Experts, authors and educators on the topics of HDMI, HDBaseT and UHD. He has authored and presented numerous courses, presenting in 3 continents, along with white papers and technical webinars, and is now a full-time member of CEDIA’s professional staff.


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