Industry display group VESA said Monday that the organization has released an “AdaptiveSync Display” standard as well as a logo program for establishing that, yes, those buttery-smooth gaming monitors can actually meet their performance claims. The organization also announced a similar verification program for video displayed on a monitor.
Basically, if a 240Hz display is accompanied by a ” VESA Certified AdaptiveSync Display 240″ logo on the box or web page, for example, you’ll know that display or laptop has been thoroughly tested by VESA at 240Hz.
“Up until now there’s been no open public standard for measuring the performance of the front-of-screen experience of these display panels,” said Roland Wooster, the chair of the Display Performance Metrics (DPM) Task Group for VESA, and a principal engineer, display and platform technologist for Intel’s Client Architecture and Innovation Group. “What we wanted to do is build an open standard, disclose what the tests are, and open it up to everyone.”
The new logo is complementary to DisplayHDR, the 2017 logo program (PDF) VESA created to establish standards for the HDR feature in laptops and standalone displays. There are over 1,000 DisplayHDR-certified devices. In 2014, VESA created and added Adaptive Sync to the DisplayPort standard, which tries to match the refresh rate of the display to what the graphics card was outputting in real time, eliminating screen tearing and creating a much smoother gaming experience. These new AdaptiveSync logos are designed to tell you how well the display adheres to that specification.
VESA
Both AMD (FreeSync) and Nvidia (G-Sync) have developed their own versions of adaptive sync, with their own logos and standardization procedures. Those compliance tests are proprietary and not really disclosed, Wooster said. VESA maintains that its own tests are both independent, open, and reviewable by consumers who can consult a list of approved displays at the AdaptiveSync Web site. However, Wooster added that he expects both AMD and Nvidia to continue with their own logo programs, so you’ll see displays with more than one logo attached.
Specifically, the VESA Adaptive-Sync display certification procedure puts the display through fifty different tests, measuring the display’s performance out of the box at the default configuration and at the display’s native resolution. If adaptive sync is not enabled by default, the display won’t pass.
There will be two logos: an AdaptiveSync logo that will be accompanied by the number representing the tested refresh rate of the display; and a MediaSync Display logo, which won’t include a refresh-rate performance number. In the latter case, VESA’s logo program is optimized for streaming, specifically how well the display can accommodate jitter as it translates that refresh rate of the source file into the refresh rate used by the display.
“Many panels will not pass,” Wooster said, especially when all of the various tests are factored in. “So this is absolutely a premium logo program. And we hope, just like DisplayHDR — you can go buy an HDR monitor. But if it’s not DisplayHDR — well, it’s HDR, but you don’t know what you’re going to get.”
How VESA AdaptiveSync Display works
The Adaptive-Sync test suite will test gaming frame rates, gray-to-gray performance, and video playback jitter and flicker elimination, Wooster said. The resulting logo will indicate the maximum refresh rate that the tests validate, whatever it might be: 300MHz, for example.
The test specifies, at a minimum, that the display must support between 60 to 144Hz refresh rates — in other words, you’ll see logos with “AdaptiveSync Display 144” at a minimum. If the display vendor specifies a greater range of refresh rates, VESA will test those too, Wooster added.
By definition, adaptive sync displays are specifically designed to compensate for the changing refresh rates of the game or video stream, so VESA’s logo program specifically stress-tests that capability. The program changes the refresh rates progresssively up and down, in a sine wave; via a sharper shift in refresh rates in a “zig zag” test; randomly; and a square wave where the display is asked to quickly switch back and forth from its minimum to its maximum refresh rate.
A second group of tests examines the gray-to-gray (G2G) response time — which, until now, has been something of a cherry-picked result, Wooster said, without a whole lot of scientific rigor to those numbers. (You’ll see many displays advertise themselves with response times of 5 ms or less.)
While a display may be capable of refreshing itself 144 times per second (144Hz) what also matters is the ability of each pixel to change color at the same pace. (This simply tells your eye that a virtual object has “moved” on your screen.) This color change is referred to gray-to-gray performance. A display that can’t achieve this may end up with a “ghosting” effect as the pixels try and keep up.
It’s also easily gamed. In fact, simply heating the display can decrease gray-to-gray response times significantly — up to twice the performance by simply increasing the temperature by ten degrees Fahrenheit, Wooster said. Display makers also use an “overdrive” function, which also tries to accelerate the G2G time. But any mismatch between the refresh rate and the G2G values essentially can cause smearing or other visual artifacts. Those image artifacts really can make the display look “broken,” he said.
“Is it fair to cherry pick the single best result, tested at abnormally high temperatures, with overdrive levels so high as to make the images look horrible? We think not,” Wooster said.
VESA’s G2G tests are thus conducted within specific (72.5F-76F) temperature limits and with 20 different G2G transitions of various types, and at factory settings. VESA also sets limits on visual quality by looking for “overshoot” and “undershoot” measurements. The tests also try and detect any dropped frames.
VESA will not publish its actual G2G results, however, Wooster said. Instead, all a display has to do to earn the logo is achieve less than a 5ms response time.
How VESA MediaSync Display works
If you’re looking to buy a display that can play back media without excessive jitter, the MediaSync Display logo was designed by VESA for that purpose. These tests focus on the ten most popular frame rate standards, including 23.976Hz (Hollywood films), 24Hz (U.S. consumer content), 25Hz (a UK frequency) and so on, as well as the minimum frame rate. A display will use “frame doubling” or “frame tripling” to approximate the slower framerates on the faster displays. VESA’s MediaSync specification requires those displays to support between 48Hz to 60Hz.
The problem that displays must deal with, among others, is what’s known as “3:2 pulldown,” which occurs when a 60Hz display, for example, has to display a 24Hz movie. If the movie was shot at 30Hz, each frame could simply be shown on the screen for 2/60 (33 ms) of a second. But the most common way of translating the 24Hz movie into a 60Hz display is to show one frame either at 3/60 of a second (50 ms) or 2/60 of a second (33ms) instead of the intended 41ms the filmmakers intended. This induces a “stuttering” effect, most noticeable as the camera pans steadily across a scene. What would normally be a “steady” pan is now jumpy, thanks to the jitter.
What VESA does is to test the display to ensure that it adapts the frequency to minimize jitter to an imperceptible 1 ms for each of the most common frequencies, Wooster said.
All of the AdaptiveSync certification will be handled by VESA approved test houses, though DisplayHDR testing has migrated to self-certification by the manufacturers themselves after a long period of compliance, Wooster said. As far as AdaptiveSync is concerned, Wooster said the “vast majority” of display vendors will participate. “I would expect that the same participants with DisplayHDR will almost certainly participate in this.”
Wooster said that VESA will continue to refine the specification so that the logo program evolves as the technology does. But as far as displays go, VESA’s logo program provides another assurance that a consumer willing to pay hundreds of dollars for an expensive display won’t have their money go to waste.
Author: Mark Hachman, Senior Editor
As PCWorld's senior editor, Mark focuses on Microsoft news and chip technology, among other beats. He has formerly written for PCMag, BYTE, Slashdot, eWEEK, and ReadWrite.