Kicking off what will be a busy May, the Video Electronics Standards Association (VESA), the leading PC display industry consortium, is rolling out a new set of performance standards for variable refresh rate displays this morning. Dubbed AdaptiveSync and MediaSync, these new test standards are designed to offer an open and industry-neutral specification for DisplayPort display behavior and performance. 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 update, just under 8 years ago VESA introduced the Adaptive-Sync specification for DisplayPort monitors. Based on the previous built-in Variable Refresh Rate technology designed for DisplayPort (eDP), Adaptive-Sync extended that technology to enable full variable refresh rate operation, as we have since come to know in PC and laptop displays.
And while the introduction of Adaptive-Sync has greatly increased the number of monitors with variable refresh rate capabilities on the market, it hasn’t been an entirely smooth experience. AMD was one of the early promoters of the technology with their Freesync initiative, which essentially carried their own promotion and certification program on their backs as well as Adaptive-Sync, but also confused a few things with a Freesync HDMI standard and basic certification. weak. Meanwhile, NVIDIA was quite late for gaming, although it 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 had to duel to some degree with different standards and certification processes (and Intel considering the odd man).
All along, Adaptive-Sync compatible displays have been hit and miss, with a wide variety of supported refresh rate ranges and lots of inconsistencies in how variable refresh actually worked. Even today, there are still displays that support varying refresh rates but offer a poor experience when they do. All of this has damaged VESA’s efforts to promote the adoption of Adaptive-Sync technology and ultimately the proliferation of variable-refresh displays and to be used to solve problems such as frame jitter.
To this end, VESA is stepping in today and will take a much more active role in the standardization and marketing of Adaptive-Sync monitors. Recognizing that support for Adaptive-Sync alone is not enough and that a good experience with a variable refresh rate monitor also requires performance limits and lows, the team has put together two new logo programs to certify performance. by Adaptive – Synchronize displays. Or, as the band likes to say, these new programs set the standard for “screen performance”.
The primary purpose of these new logo programs is to help shoppers identify monitors that efficiently implement Adaptive-Sync. There is also a secondary purpose in helping VESA member companies clearly communicate to those buyers that their variable refresh rate monitors are, to put it politely, legitimately good, as the Adaptive-Sync implementation doesn’t offer any. quality assurance. This of course is an area where both NVIDIA and AMD have a hand, with their G-Sync and Freesync certification programs respectively, with a mixed history of results thanks to multiple standards and the use of proprietary technologies. As a result, VESA wants to do what neither one already does in creating a set of open standards that aren’t tied to a specific manufacturer and relying solely on DisplayPort’s Adaptive-Sync technology.
VESA, in turn, will essentially address the subject from both ends of the spectrum. At the high end there will be the new VESA certified AdaptiveSync display standard, designed to be a compliance standard for high-end gaming displays and has some very stringent requirements to meet. At the other end of the spectrum there is VESA certified MediaSync, which is a much simpler specification aimed at pointing out displays that offer basic and effective support for varying refresh rate for media consumption purposes, and with no emphasis on gaming. Basically, AdaptiveSync is a superset of MediaSync, so while both standards exist on the market you won’t see logo displays for either; if a display meets AdaptiveSync standards, that’s more than enough to meet multimedia 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 compliance test that takes a variety of factors into consideration. Not only the basic characteristics such as the refresh rates defined in the standards, but also the standards for flicker (or rather its absence), lost frames, jitter, pixel response times (G2G) and ghosting / overshoot / undershoot. Aside from HDR functionality (which is another thing for numerous reasons), AdaptiveSync covers all relevant requirements for a high-end gaming display.
This all came as a bit of a surprise to me. When VESA first informed me that they were working on a quality standard for variable refresh displays, I must admit I was skeptical. The consensus-based nature of the group means that VESA performance standards have at times been held back by the need to satisfy hardware manufacturers who want many (if not all) of their products to meet a new standard. This was more explicitly the case with the DisplayHDR certification, which while a technically sound program at the higher levels, is damaged by the existence of the DisplayHDR 400 level, rendering the DisplayHDR branding itself meaningless.
This is clearly something VESA has taken to heart, as, to my surprise, AdaptiveSync isn’t making such compromises. Instead, the group focused on developing a high-end specification that isn’t watered down to encompass or qualify more basic displays. As a result, most Adaptive-Sync compatible displays on the market currently do not meet AdaptiveSync display standards and most game displays are likely to fail as well. VESA set out to create a high-end standard and they clearly stayed true to the matter until the very end.
And to be sure, the AdaptiveSync display standard is simply a performance standard, it doesn’t define new technologies. Then the standard can be used to test and certify existing PC monitors, integrated displays (PC AIO) and laptop displays, provided those devices are connected via a DisplayPort / eDP standard. It should be noted that this technically means that the AdaptiveSync standard only applies to the DisplayPort input on a device and not the HDMI inputs. But, since 99% of the hard work to deliver a good variable refresh rate experience occurs under the hood with components like TCON and backlight, I’d be surprised to see this to be an issue.
Refresh rates: 60-144 minimum, LFC required
By plunging into the same AdaptiveSync display standard, VESA started things off with significant refresh rate requirements. A compliant display must support a variable refresh rate range of at least 60Hz to 144Hz, the minimum and magic 2.4x range required to support low framerate compensation (LFC). Displays can drop below this value for minimum (e.g. 48Hz) and above that for maximum (see: 360Hz displays), but 60-144 is the smallest range you can qualification. And it has to be outside the box; displays that must be “overclocked” in any way to meet the minimum requirements will not be of quality. This is true for all tests, in fact, as AdaptiveSync certification tests are conducted with monitors running at their native resolution and set to default and default configuration.
In this sense, VESA is also testing for lost frames, as there have apparently been some monitors that accept more frames than they can actually display. As a result, the compliance test looks for dropped frames at both fixed and variable refresh rates to ensure that every frame is displayed.
Flicker: min to max test and everything in between
The second major area of concern for AdaptiveSync compliance testing is display flickering, which essentially covers a whole suite of display and backlight glitches that can occur with variable refresh rate displays. Using a dedicated probe (presumably a photodiode), the VESA test regime looks for evidence of visible flicker, with a technical requirement of no more than -50 dB of flicker, regardless of the 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 look at frequencies that human eyes are most sensitive to.
The test, in turn, breaks things down into looking for flicker at common frame rates / refresh rates for media (23.976 fps / 71.928 Hz, etc.) and the panel’s minimum refresh rate, as well as running several tests for flicker in full variable refresh rate scenarios, where the refresh rate changes from frame to frame.
The compliance test for variable refresh mode is based on four refresh rate models to ensure that displays can properly handle both slow and fast refresh rates. These 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 particularly brutal as it requires quick switching between minimum and maximum refresh rates. The random test is also quite capable of triggering monitors, as it can have displays switching to significantly different refresh rates in one go, instead of smoothly increasing or decreasing.
And while the AdaptiveSync display compliance test doesn’t have an explicit test for backlight or gamma flicker (a rather common problem in early Adaptive-Sync displays), according to the group, they feel their flicker test should be sensitive enough to be detected those specific phenomena.