So, you’re looking at a monitor or laptop that says it has Adaptive-Sync or variable refresh rates. Maybe it’s Nvidia G-Sync or AMD FreeSync. Maybe the vendor was detailed enough to include an Adaptive-Sync range, indicating the refresh rate range, as well as a response time figure and overdrive feature promising extra-smooth video playback. But then you see a bunch of other monitors and laptops claiming the same thing. How can you tell which display will offer a better media experience?

To help, the Video Electronics Standards Association (VESA) launched a certification program Monday for PC monitors and laptop displays with Adaptive-Sync. The Adaptive-Sync Display Compliance Test Specification (Adaptive-Sync Display CTS) aims to provide more insight into the screen tear-fighting technology.

The program, which has already certified some products, has more than 50 criteria for its two tiers: MediaSync Display, which is focused on video playback and requires an Adaptive-Sync range of at least 48 to 60 Hz, and Adaptive-Sync Display, which is focused on gaming and requires an Adaptive-Sync rage of at least 60 to 144 Hz.

A deeper look at Adaptive-Sync performance

In 2014, VESA—a nonprofit group composed of hardware, software, computer, and component manufacturers that also makes the standards for DisplayPort, DisplayHDR, and VESA monitor mounts—added Adaptive-Sync protocols to the DisplayPort video interface. Adaptive-Sync, which includes displays like Nvidia G-Sync and AMD FreeSync, is supposed to make video playback look smoother by eliminating screen tears, juddering, and flickering. Adaptive-Sync also seeks to accommodate lower power usage and efficiency when dealing with content playing at various framerates.

Adaptive-Sync is now in all types of monitors, including gaming and general-use ones. It’s also supported by the major GPU vendors. Nvidia’s and AMD’s takes provide further optimizations for their graphics cards and may have other image quality requirements, depending on the type of G-Sync or FreeSync.

With the goal of providing a more detailed preview of a monitor’s or laptop’s expected Adaptive-Sync performance with default settings, VESA—after two years of development with more than two-dozen members, including Nvidia, AMD, Intel, and makers of displays, display drivers, CPUs, and other components, is launching an Adaptive-Sync certification program with more stringent requirements. You can be an Adaptive-Sync, G-Sync, and/or FreeSync display without the new MediaSync Display or Adaptive-Sync Display standards. But earning one of the new logos means the monitor has gone through extensive VESA testing, which we’ll get into soon.

But before that, we should note that monitors require DisplayPort to get one of the certifications. This disqualifies HDMI-only Adaptive-Sync monitors from earning the new logo. The move becomes more interesting when considering that HDMI 2.1 introduced variable refresh rates to the standard.

Ramped-up requirements for both tiers

The most basic requirements of the new tiers are set Adaptive-Sync ranges. The MediaSync Display tier requires an Adaptive-Sync range that goes as low as at least 48 Hz and as high as at least 60 Hz. For the gaming-centered Adaptive-Sync Display tier, the range is a broader 60 to 144 Hz.

But that’s just the start of what a monitor has to go through to attain one of VESA’s logos.

Judder testing

To earn the MediaSync or Adaptive-Sync certification, a display must exhibit less than 1 ms of judder, which is much lower than what’s supposed to be visible to the human eye, according to VESA.

That figure has to be met across 10 international framerate standards: 23.976 Hz (Hollywood film); 24, 30, and 60 Hz (typically content filmed on consumer cameras, like YouTube videos or something being played back locally), 25 Hz (British TV), 29.97 Hz (US TV), 47.952 Hz, (which is rare but used in some movies), 48 Hz (also used in the rare film), 50 Hz (British sports), and 59.94 Hz (US sports).

Then, VESA tests the display at the monitor’s minimum Adaptive-Sync range. If the monitor has an Adaptive-Sync range of 40 to 60 Hz, for example, VESA will test it at 40 Hz, even though the MediaSync Display tier only calls for a range that goes as low as 48 Hz, and the Adaptive-Sync tier 60 Hz. If a monitor’s Adaptive-Sync range has a higher minimum than what the certification calls for, VESA frame-doubles the ones that are slower than the minimum.

One common cause of judder is the 3:2 pulldown, which is used to display Hollywood films made at 23.976 Hz and results in one dropped frame per second. VESA’s certification seeks to eliminate the need for the 3:2 pulldown.

https://arstechnica.com/?p=1851262