VESA launches variable refresh display performance standards: AdaptiveSync and MediaSync
Kicking off what is expected to be a busy May, this morning the Video Electronics Standards Association (VESA), the PC monitor industry’s leading consortium, is rolling out a new set of performance standards for variable refresh rate displays. . Dubbed AdaptiveSync and MediaSync, these new test standards are designed to provide a neural, open industry specification for the behavior and performance of DisplayPort displays. AdaptiveSync is a standard designed for high-end gaming displays, while MediaSync aims to eliminate video jitter on a much wider range of devices.
As a quick recap, just under 8 years ago VESA introduced its Adaptive-Sync specification for DisplayPort monitors. Based on earlier variable refresh rate technology designed for embedded DisplayPort (eDP), Adaptive-Sync has extended this technology to enable full variable refresh rate operation, as we’ve since learned on PC and desktop displays. ‘laptop.
And while the introduction of Adaptive-Sync has dramatically increased the number of monitors with variable refresh rate capabilities on the market, it hasn’t been an entirely smooth experience. AMD was an early promoter of the technology with its Freesync initiative, which basically added its own promotion and certification program to Adaptive-Sync, but also muddled some things with an HDMI Freesync standard and basic certification weak. Meanwhile, NVIDIA was quite late to the game, although they finally embraced support for the VESA standard in 2019, adding support for Adaptive-Sync alongside their proprietary G-Sync standard. existing. But even after that, it’s still AMD and NVIDIA dueling to some extent with differing standards and certification processes (and Intel looks like the odd man out).
All the while, Adaptive-Sync-enabled displays have been hit and miss, with a wide variety of supported refresh rate ranges and plenty of inconsistencies in how variable refresh actually works. Even today, there are still displays that support variable refresh rates but provide a subpar experience. All of this hurt VESA’s efforts to promote the adoption of Adaptive-Sync technology, and eventually for variable refresh displays to proliferate and be used to address issues such as 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 Adaptive-Sync support alone is not enough and that a good experience with a variable refresh rate monitor also requires performance limits and minimums, the group has implemented two new logo programs to certify the performance of Adaptive -Sync displays. Or, as the band likes to put it, these new programs set standards for “performance in front of the screen.”
The main purpose of these new logo programs is to help buyers identify monitors that competently implement Adaptive-Sync. There’s 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, because the implementation of Adaptive-Sync n comes with no warranty of quality. This is of course an area in which NVIDIA and AMD have a hand in, with their G-Sync and Freesync certification programs respectively, with a mixed track record of results through multiple standards and the use of proprietary technologies. Therefore, VESA wants to do what none of them already do by creating a set of open standards that are not tied to a specific manufacturer and rely solely on DisplayPort’s Adaptive-Sync technology.
VESA, in turn, will essentially approach the subject from both sides of the spectrum. At the high end will be the new VESA-certified AdaptiveSync display standard, which is designed to be a compliance standard for high-end gaming displays and has very strict requirements to meet. At the other end of the spectrum is VESA-certified MediaSync, which is a much simpler specification aimed at flagging displays that offer basic and effective variable refresh rate support for media consumption purposes – and without a focus on gaming. In practice, AdaptiveSync is a superset of MediaSync, so although both standards exist in the market, you won’t see logo displays for both; if a display meets AdaptiveSync standards, it’s more than enough to meet media playback needs as well.
AdaptiveSync: LFC, no flicker and no shenanigans
We’ll start with an overview of the high-end AdaptiveSync display standard. Designed for gaming monitors (or more accurately, “gaming frame rates”), AdaptiveSync is a compliance test that examines a number of factors. Not only core features such as refresh rates are defined in the standards, but also standards for flicker (or rather lack thereof), dropped frames, jitter, pixel response times (G2G) and framerates ghosting/overshoot/undershoot. Short of HDR functionality (which is a whole other ballgame for many reasons), AdaptiveSync covers all the relevant requirements for a high-end gaming display.
All this surprised me a bit. When VESA first informed me that they were working on a quality standard for variable refresh displays, I readily admit I was skeptical. The consensus nature of the group means that VESA performance standards have at times been held back by the need to please hardware manufacturers who want many (if not all) of their products to meet a new standard. This has been the most explicit case for the DisplayHDR certification, which, although a technically sound program at the higher levels, is affected by the existence of the DisplayHDR 400 level, which makes the DisplayHDR certification in itself meaningless.
This is clearly something VESA has taken to heart, because, to my surprise, AdaptiveSync makes no such compromises. Instead, the group has focused on developing a high-end spec that isn’t watered down to encompass or qualify more basic screens. Therefore, most Adaptive-Sync compatible displays on the market today do not meet AdaptiveSync display standards, and even most video game screens will likely fail as well. VESA set out to create a high-end standard, and they clearly stick to their guns on the matter until the very end.
And to be sure, the AdaptiveSync display standard is just a performance standard – it doesn’t define any new technology. Thus, the standard can be used to test and certify existing PC monitors, integrated displays (PC AIO) and laptop displays, as long as these devices are connected via a DisplayPort/eDP standard. It should be noted that this technically means that the AdaptiveSync standard only applies to a device’s DisplayPort input and not HDMI inputs. But, since 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 if that was an issue.
Refresh rate: 60-144 minimum, LFC required
Diving into the AdaptiveSync display standard itself, VESA started things off with some serious refresh rate requirements. A compliant display must support a variable refresh rate range of at least 60Hz to 144Hz – the minimum magic range of 2.4x needed to support Low Frame Rate Compensation (LFC) . Screens can go below for the minimum (eg 48Hz) and above for the maximum (see: 360Hz screens), but 60-144 is the smallest range that qualifies. And it must be ready to use; monitors that need to be “overclocked” in any way to meet the minimums will not be quality. This goes for all tests, in fact, because AdaptiveSync certification tests are performed with monitors running at their native resolution and set to their default, out-of-the-box configuration.
Along these lines, VESA also tests for dropped frames, as some monitors apparently accept more frames than they can display. Therefore, the conformance test looks for dropped frames at both fixed and variable refresh rates, to ensure that every frame is displayed.
Flicker: test from min to max, and everything in between
The second major area of focus for the AdaptiveSync compliance test is display flickering, which basically covers a whole host of display and backlight anomalies that can occur with variable refresh rate displays. Using a dedicated probe (presumably a photodiode), VESA’s test regime looks for evidence of visible flicker, with a technical requirement of no more than -50dB of flicker, regardless of refresh rate. Here, VESA relies on the Japan Electronic Information Technology Association’s (JEITA) existing perception-based method for calculating flicker, which is weighted to examine the frequencies to which human eyes are most sensitive.
The test, in turn, breaks things down by looking for flicker at common media frame rates/refresh rates (23.976 fps/71.928 Hz, etc.) and minimum panel refresh rate, as well as by running multiple flicker tests in full variable refresh rate scenarios, where the refresh rate changes from frame to frame.
Compliance testing for Variable Refresh Mode relies on four refresh rate models to ensure that displays can properly handle slow and fast changing refresh rates. These patterns are sine wave, zigzag pattern, square wave and finally full random test. According to VESA, the square wave test in particular is particularly brutal because it requires rapid switching between minimum and maximum refresh rates. The random test is also quite capable of tripping monitors, as it can have displays jumping to wildly different refresh rates all at once, instead of smoothly ramping up or down.
And while the AdaptiveSync display compliance test doesn’t have an explicit test for backlighting or gamma flicker (a fairly common problem in early Adaptive-Sync displays), according to the group, they believe their flicker test should be sensitive enough to detect these particular phenomena.