Kick off a busy month of May, this morning, the Video Electronics Standards Association (VESA), the PC monitor industry’s premier consortium, is introducing a new set of variable refresh rate monitor performance standards. Known as AdaptiveSync and MediaSync, these new test standards are designed to provide industry-leading and open specifications for the behavior and performance of DisplayPort displays. AdaptiveSync is a standard designed for high-end gaming monitors, while MediaSync is designed to eliminate video judder on a wider range of devices.
As a quick recap, it was less than 8 years ago that VESA introduced the Adaptive-Sync specification for DisplayPort monitors. Building on an earlier variable refresh rate technology designed for Embedded DisplayPort (eDP), Adaptive Sync extends this technology to allow fully variable refresh rate operation, as we know it in PC and laptop monitors.
While the introduction of Adaptive-Sync has greatly increased the number of monitors on the market with variable refresh rate capability, it’s not a completely smooth experience. AMD was an early mover in this technology, and their Freesync program basically piggybacked on their own promotion and certification program on top of Adaptive-Sync, but also confused things with the Freesync HDMI standard and weak foundational certification. Nvidia, meanwhile, was late to the game, although they finally embraced support for the VESA standard in 2019 — adding Adaptive-Sync support alongside the existing proprietary G-Sync standard. But even after that, AMD and NVIDIA were dueling somewhat over different standards and certification processes (while Intel was seen as the oddball).
Monitors with adaptive sync have been hit and miss all the time, with a wide range of supported refresh rates and a lot of inconsistency in how variable refresh actually works. Even today, there are monitors that support variable refresh rates, but when doing so, they provide a sub-par experience. All of this undermined VESA’s push to adopt Adaptive-Sync technology, which eventually led to the proliferation of variable-refresh displays to address issues like frame jitter.
To that end, today VESA is stepping in and will play a more active role in the standardization and marketing of Adaptive-Sync monitors. Recognizing that support for the Adaptive-Sync feature is not enough and that a good experience with a variable refresh rate display also requires boundaries and minimums in terms of performance, the team has put together two new logo programs to demonstrate the performance of Adaptive-Sync Display . Or, as the group likes to say, these new programs set the bar for “pre-screen performance.”
The primary purpose of these new logo programs is to help buyers identify displays that are proficient at implementing adaptive sync. There is also a secondary purpose to help VESA member companies clearly communicate their variable refresh rate monitors to these buyers, which, politely, is legitimately good, since there is no guarantee of quality in implementing adaptive sync. This is of course an area where both NVIDIA and AMD have gone through the G-Sync and Freesync certification programs respectively, with a long history of results due to the use of multiple standards and proprietary technologies. So VESA wants to do what none of them have done, which is to develop a set of open standards that are not tied to a particular manufacturer, and rely entirely on DisplayPort’s adaptive sync technology.
VESA, in turn, will basically solve this problem from both ends of the spectrum.High end will be new VESA Certified AdaptiveSync The display standard, which is designed to be the consistency standard for high-end gaming monitors, and has some pretty strict requirements to match.On the other end of the spectrum is VESA Certified MediaSync, which is a simpler specification meant to label monitors that offer basic and effective variable refresh rate support for media consumption purposes – and don’t emphasize any gaming. In fact, AdaptiveSync is a superset of MediaSync, so while both standards exist on the market, you won’t see a monitor with a logo for both; if the monitor is AdaptiveSync compliant, it’s good enough for media playback as well.
AdaptiveSync: LFC, no flicker, no mischief
We’ll start with the high-end AdaptiveSync display standard. Designed for gaming monitors (or more specifically, “game frame rate”), AdaptiveSync is a conformance test that takes many factors into consideration. Not only basic characteristics like refresh rate, but also flicker (or rather non-existence), dropped frames, jitter, pixel response time (G2G), and ghosting/overshoot/undershoot are defined in the standard. Lack of HDR capability (which is another story entirely for a number of reasons), AdaptiveSync covers all the relevant requirements for a high-end gaming monitor.
All of this took me by surprise. When VESA first told me they were setting quality standards for variable refresh monitors, I’ll admit I was skeptical. The consensus-driven nature of the organization means that VESA performance standards are sometimes hindered by the need to please hardware manufacturers who want to make many, if not all, products compliant with the new standard. This is most evident in DisplayHDR certification, which, while it is a technically sound procedure at higher layers, is compromised by the presence of the DisplayHDR 400 layer, rendering DisplayHDR certification itself meaningless.
This is clearly something VESA has in mind, because to my surprise AdaptiveSync doesn’t make any such compromises. Instead, the group went all out to develop a high-end spec that wouldn’t be watered down to encompass or qualify a more basic display.Therefore, most monitors that support Adaptive-Sync on the market today do not conform to the AdaptiveSync display standard, and even most gamble Displays may also fail. VESA set out to create a high-end standard, and they’re clearly sticking to it.
To be sure, the AdaptiveSync display standard is only a performance standard – it does not define any new technology. Therefore, the standard can be used to test and certify existing PC monitors, integrated monitors (AIO PCs) and laptop monitors, as long as these devices are connected via the DisplayPort/eDP standard. It should be noted that this technically means that the AdaptiveSync standard only applies to DisplayPort inputs on the device, not HDMI inputs. However, since 99% of the hard work to deliver a good variable refresh rate experience happens behind the scenes with components like the TCON and backlight, I’d be surprised to see that this is a problem.
Refresh rate: 60-144 minimum, requires LFC
Digging into the AdaptiveSync display standard itself, VESA has started to have very high refresh rate requirements. Compatible monitors need to support a variable refresh rate range of at least 60Hz to 144Hz – the minimum, magic 2.4x range required for Low Frame Rate Compensation (LFC) support. Monitors can go below this minimum value (eg 48Hz) and above this maximum value (see: 360Hz monitors), but 60-144 is the minimum eligible range. It has to work out of the box; a monitor that needs to be “overclocked” in any way to meet the minimum requirements is not of high quality. In fact, this applies to all tests, as the AdaptiveSync certification tests are performed with the monitor running at native resolution and set to the default out-of-the-box configuration.
Along those lines, VESA is also testing for dropped frames, as apparently some monitors accept more frames than they actually display. Therefore, compliance testing looks for dropped frames at fixed and variable refresh rates to ensure that every frame is displayed.
Blink: Test min to max, and everything in between
The second major area of focus for AdaptiveSync compliance testing is display flicker, which basically covers the full set of display and backlight anomalies that can occur with variable refresh rate displays. VESA’s test mechanism uses a dedicated probe (probably a photodiode) to look for evidence of visible flicker, regardless of refresh rate, the specification requires no more than -50 dB of flicker. Here VESA relies on an existing perception-based flicker calculation method from the Japan Electronics and Information Technology Association (JEITA), which is weighted to see the frequencies to which the human eye is most sensitive.
This test, in turn, breaks things down into looking for flicker at common frame rates/media refresh rates (23.976fps/71.928Hz, etc.) and the panel’s minimum refresh rate, as well as running multiple fully variable flicker test refresh rate scenarios where the refresh rate Change frame by frame.
Compliance testing for variable refresh modes relies on four refresh rate modes to ensure the display can properly handle slow and rapidly changing refresh rates. The patterns are sine wave, sawtooth pattern, square wave, and finally a completely random test. According to VESA, the square wave test is especially brutal because it requires quick switching between minimum and maximum refresh rates. Random testing also has a good chance of tripping the monitor, as it can switch the monitor to significantly different refresh rates all at once, rather than ramping up or down smoothly.
According to the group, while the AdaptiveSync monitor compliance test does not explicitly test for backlight or gamma flicker (some problems common to early Adaptive-Sync monitors), they believe their flicker test should be sensitive enough to accept those specific phenomena .