VESA Releases Variable Refresh Display Performance Standards: AdaptiveSync and MediaSync

Kicking off what will be a busy May, this morning the Video Electronics Standards Association (VESA), the PC display industry’s leading consortium, is implementing a new set of performance standards for variable refresh rate displays. Known as AdaptiveSync and MediaSync, these new test standards are designed to provide an open, neural industry specification for DisplayPort display behavior and performance. AdaptiveSync is a standard designed for high-end gaming displays, while MediaSync aims to eliminate video jitter across a much wider range of devices.

As a quick refresher, just under 8 years ago, VESA introduced its Adaptive-Sync specification for DisplayPort monitors. Building on previous variable refresh rate technology designed for integrated DisplayPort (eDP), Adaptive-Sync extended that technology to enable full variable refresh rate operation as we’ve known it ever since in PC and laptop displays.

And while the introduction of Adaptive-Sync greatly increased the number of monitors with variable refresh rate capabilities on the market, it hasn’t been an entirely seamless experience. AMD was an early promoter of the technology with its Freesync initiative, which essentially supported its own promotion and certification program in addition to Adaptive-Sync, but also confused some things with a Freesync HDMI standard and weak base certification. NVIDIA, meanwhile, was pretty late to the game, though they did finally adopt support for the VESA standard in 2019, adding Adaptive-Sync support alongside their existing proprietary G-Sync standard. But even after this, AMD and NVIDIA dueled to some extent with different standards and certification processes (and Intel looks like the odd one out).

Meanwhile, Adaptive-Sync compatible displays have been hit or miss, with a wide variety in supported refresh rate ranges and a lot of inconsistency in how variable refresh actually works. Even today, there are still displays that support variable refresh rates, but offer an inferior experience doing so. All of this has undermined VESA’s efforts to promote the adoption of Adaptive-Sync technology and ultimately for variable refresh displays to proliferate and be used to solve problems like frame jitter.

To that end, VESA is stepping in today and will take a much more active role in the standardization and commercialization of Adaptive-Sync monitors. Recognizing that supporting the Adaptive-Sync feature alone is not enough, and that a good experience with a variable refresh rate monitor also requires limits and minimums in terms of performance, the group has created two new logo programs to certify the performance of Adaptive -Synchronize screens. Or, as the group likes to say, these new shows set standards for “performance in front of the screen.”

The main goal of these new logo programs is to help buyers identify monitors that competently implement Adaptive-Sync. There is also a secondary purpose of helping VESA member companies clearly communicate to those buyers that their variable refresh rate monitors are, to put it politely, legitimately good, since the Adaptive-Sync implementation does not come with any guarantees of reliability. quality. Of course, this is an area where both NVIDIA and AMD participate, with their G-Sync and Freesync certification programs respectively, with a mixed record of results thanks to multiple standards and the use of proprietary technologies. Consequently, VESA wants to do what neither already does by creating a set of open standards that aren’t tied to a specific manufacturer and rely solely on DisplayPort’s Adaptive-Sync technology.

VESA, in turn, will essentially approach the issue from both ends of the spectrum. In the high range will be the new VESA-certified AdaptiveSync display standard, which is designed to be a conformance standard for high-end gaming displays and has some very strict requirements to meet. At the other end of the spectrum is VESA Certified MediaSync, which is a much simpler specification intended to mark displays offering basic and effective variable refresh rate support for media consumption purposes, and with no emphasis on gaming at all. In practice, AdaptiveSync is a superset of MediaSync, so even though there are both standards on the market, you won’t see both logo screens; if a display meets AdaptiveSync standards, then it’s more than enough to satisfy media playback needs as well.

AdaptiveSync: LFC, no flicker and no shenanigans

We’ll start with a look at the high-end AdaptiveSync display standard. Designed for gaming displays (or more specifically, “gaming frame rates”), AdaptiveSync is a conformance test that looks at a number of factors. Not only basic characteristics like refresh rates are defined in the standards, but also standards for flickering (or rather the absence of it), dropped frames, jitter, pixel response times (G2G), and ghosting/overshoot/undershoot. Short of HDR functionality (which is another pot of fish for numerous reasons), AdaptiveSync covers all the relevant requirements for a high-end gaming display.

All of which has surprised me a bit. When VESA first informed me that they were working on a quality standard for variable refresh displays, I freely admit I was skeptical. The consensus-driven nature of the group means that VESA’s performance standards have sometimes been held back by the need to pander to hardware manufacturers who want many (if not all) of their products to comply with a new standard. This has been the most explicit case of DisplayHDR certification, which while a technically sound program at the higher levels, is handicapped by the existence of the DisplayHDR 400 level, making the DisplayHDR brand itself meaningless.

Clearly, this is something that VESA has taken very seriously, as to my surprise AdaptiveSync isn’t making such concessions. Instead, the group has gone to great lengths to develop a high-end spec that isn’t watered down to encompass or qualify more basic displays. As a result, most Adaptive-Sync compatible displays on the market right now will not meet the AdaptiveSync display standards, and even most gaming Screens are also likely to fail. VESA set out to create a high-end standard, and they clearly stand by the issue to the end.

And to be sure, the AdaptiveSync display standard is simply a performance standard, it doesn’t define any new technology. Therefore, the standard can be used to test and certify existing PC monitors, integrated displays (PC AIOs), and laptop displays, as long as those devices are connected via a DisplayPort/eDP standard. It should be noted that technically this means that the AdaptiveSync standard only applies to the DisplayPort input on a device and not to the HDMI inputs. But given that 99% of the hard work to deliver a good variable refresh rate experience happens under the hood with components like the TCON and backlight, I’d be surprised to see this be an issue.

Refresh Rates: 60-144 minimum, LFC required

Diving into the AdaptiveSync display standard itself, VESA has started with significant refresh rate requirements. A compatible display must support a variable refresh rate range of at least 60Hz to 144Hz, the magic minimum range of 2.4x required to support Low Frame Rate Compensation (LFC). Screens can go below this for the minimum (eg 48Hz) and above that for the maximum (see: 360Hz screens), but 60-144 is the smallest qualifying range. And it must be out of the box; screens that need to be “overclocked” in some way to meet the minimums will not have quality. In fact, that goes for all tests, as AdaptiveSync certification tests are done with monitors running at their native resolution and set to their default settings out of the box.

On that note, VESA is also testing for dropped frames, as there have apparently been some monitors that accept more frames than they can actually display. As a result, the conformance test looks for dropped frames at both fixed and variable refresh rates, to ensure all frames are displayed.

Blinking: min to max test and everything in between

The second main focus area for AdaptiveSync conformance testing is screen flickering, which essentially covers a full set of display and backlight anomalies that can occur with variable refresh rate displays. Using a dedicated probe (presumably a photodiode), the VESA testing regime looks for evidence of visible flicker, with a technical requirement of no more than -50 dB of flicker regardless of refresh rate. In this case, VESA relies on the existing perception-based method of the Japan Electronic Information Technology Association (JEITA) to calculate flicker, which is weighted to look at the frequencies to which human eyes are most sensitive. .

The test, in turn, breaks things down to look for flicker at common media frame rates/refresh rates (23.976fps/71.928Hz, etc.) and the minimum panel refresh rate, as well as running various flicker tests in full variable refresh rate scenarios, where the refresh rate changes from frame to frame.

The conformance test for variable refresh mode is based on four refresh rate patterns to ensure that displays can adequately handle slowly and rapidly changing refresh rates. Those patterns are a sine wave, a zigzag pattern, a square wave, and finally a full random test. According to VESA, the square wave test in particular is especially brutal as it requires rapid switching between minimum and maximum refresh rates. Random testing is also quite capable of tripping up monitors, as it can cause screens to switch to significantly different refresh rates in one go, rather than smoothly ramping up or down.

And while the AdaptiveSync display conformance test doesn’t have an explicit test for backlight or gamma flicker (a somewhat common problem on early Adaptive-Sync displays), according to the group, they believe their flicker test should be sensitive enough to detect those specific phenomena.

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