VESA announced yesterday what they refer to as “the first publicly open standard for front-of-screen performance of variable refresh rate displays”. More than two years in development, VESA’s new Adaptive-Sync Display Compliance Test Specification and logo programs have been established with contributions by more than two dozen VESA member companies spanning the display ecosystem, including major OEMs that supply displays, graphic cards, CPUs, panels, display drivers and other components. It’s a new certification and testing scheme designed to make life simpler and clearer for the consumer, but does it really achieve that?
Background and Development
In 2014, VESA added Adaptive-Sync protocols to the VESA DisplayPort video interface standard to enable smoother, tear-free images for gaming, as well as enable lower power and greater efficiency in displaying content rendered at a wide range of frame rates. Since this introduction, VESA’s Adaptive-Sync technology has seen widespread adoption across the display industry and is now supported by all major GPU chipset vendors. However, while many PC and laptop displays currently support Adaptive-Sync protocols, until now VESA claim there has been according to VESA “no open standard in measuring the level of performance or quality of Adaptive-Sync support for any given display.”
A bit of a strange claim – what about AMD FreeSync or NVIDIA’s G-sync Compatible schemes?
There’s no cost for the certification as such, but vendors will have to pay to have their display tested at an “Authorized Test Center” as their FAQ explains:
What does an OEM need to do in order to get their display product certified?https://www.adaptivesync.org/faq/
OEMs who are VESA members (and with over 300 member companies, almost anyone involved in the display industry is already a VESA member) can send their hardware to one of VESA’s approved Authorized Test Centers (ATCs), pay the testing fee charged by the third-party test house, and obtain a pass or fail certification. VESA does not charge any fee for certification….All certifications for the VESA AdaptiveSync Display are required to be performed by a VESA approved ATC.
Compliance Test Specification and the New Logos
According to VESA, the Adaptive-Sync Display Compliance Test Specification (Adaptive-Sync Display CTS) provides for a comprehensive and rigorous set of more than 50 test criteria, an automated testing methodology and performance mandates for PC monitors and laptops supporting VESA’s Adaptive-Sync protocols. The Adaptive-Sync Display CTS also establishes a product compliance logo program which will allow manufacturers to use a specific new logo for their display if it passes the testing.
The logo will confirm the certification of the screen and will be combined with a specific number reflective of the displays max refresh rate in VRR gaming. Options will be available for 144Hz, 165Hz, 240Hz, 360Hz and so on. Their FAQ also confirms they will provide logos to support other random numbers including weird overclocked refresh rates (170Hz, 175Hz and so on) as long as the display passes the tests.
By establishing the VESA Certified AdaptiveSync Display logo programs, VESA will enable consumers to easily identify and compare the variable refresh rate performance of displays supporting Adaptive-Sync prior to purchase. Only displays that pass all Adaptive-Sync Display CTS and VESA DisplayPort compliance tests can qualify for the VESA Certified AdaptiveSync Display logos.
Testing Criteria Explored and Our Comments
The VESA Adaptive-Sync Display CTS includes more than 50 automated display performance tests covering several key variables, including refresh rate, flicker, gray-to-gray response time (including limits on overshoot and undershoot to ensure high-quality images), video frame drop, and video frame rate jitter.
As required by the VESA Adaptive-Sync Display CTS, all displays must be tested in the factory shipping state or default factory mode configuration, as well as tested in ambient room temperature, in order to ensure the display is evaluated and certified under realistic user conditions. This presumably means that manufacturers will have to pay attention to their default overdrive configuration if they want to meet these criteria which is a good thing – hopefully no more crazy default high overdrive modes. Although how would they account for a screen with perhaps different overdrive modes suited to different refresh rates? It’s very common for adaptive-sync screens to NOT include variable overdrive, and this normally means you do not get a “single overdrive setting” experience. You often have 2 or maybe more overdrive modes you might need to use depending on your active refresh rate. This makes certification and testing complex.
In addition, all displays that meet the requirements for VESA AdaptiveSync Display logo certification must also be tested and certified to VESA’s DisplayPort standard. The majority of desktop and laptop GPUs introduced within the last two years are capable of supporting VESA’s Adaptive-Sync protocols. VESA encourages consumers to check with their GPU vendor to verify that their GPU and software driver enables Adaptive-Sync operations with VESA Certified AdaptiveSync Display products by default.
The following table summarizes the Adaptive-Sync Display specifications that vary across the logo performance tiers.
In addition to the logo-specific tests above, all qualifying devices must meet the following specifications that apply to all logo performance tiers:
The criteria for testing and certification are outlined above and documented on VESA’s website. Some initial observations would be:
- This certification will not be available for any screen with a refresh rate lower than 144Hz – what about those screens that feature adaptive-sync even if they’re only 60Hz? What about 120Hz screens that are still sometimes released? I’m thinking especially here about some of the emerging OLED panels incorporated in to “monitors”. VESA say in their FAQ that “We wanted to set a high minimum bar to establish this standard as a premium logo program. 144Hz was chosen as a suitable minimum requirement that could be achieved by gaming displays from 1080P through 4K resolutions.”
- The lower end doesn’t provide a particularly low refresh rate if you only need to reach to 60Hz to get the certification, that is a little limiting
- Some commentary about the response time requirements is included in the following section
- The max flicker allowed is listed as -50dB on all refresh rate tests, but this is not really translatable in to something that a consumer might understand? What is it even supposed to mean when it comes to visually perceived flicker? The testing approach is explained in more detail in their CTS documentation but it still feels like it’s very complex for an average user to understand. Are we to assume that if it’s certified as “AdaptiveSync” then it means no flicker in practice?
According to Roland Wooster, chairman of the VESA Display Performance Metrics Task Group responsible for the Adaptive-Sync Display CTS and the association’s representative from Intel Corporation for HDR and Adaptive Sync display technology, “The Adaptive-Sync Display CTS builds upon the foundation that VESA laid with the introduction of the Adaptive-Sync protocols eight years ago. It provides an open, industry-wide and brand-agnostic standard backed by a logo program that gives consumers a guarantee that the displays that they’re buying for gaming or for media playback will meet a clearly defined minimum set of front-of-screen performance criteria when used with a suitable GPU. In designing the test specification and logo program, VESA explicitly set a high bar on performance criteria and testing methodology with tighter criteria than many existing specs and logo programs. As with all of our standards, VESA will continue to develop and refine the Adaptive-Sync Display CTS to address new display developments and market needs in order to enable further improvements in visual quality and user-experience for consumers.”
Response Time Measurements
Following on from our notes about the testing criteria above, we wanted to discuss the G2G response time requirements a bit further.
The G2G response time criteria of less than or equal to 5ms G2G average are based on a traditional measurement method (as discussed in our article here) which is perhaps not optimal for reflecting true response time performance. This would have been better if it was based on a more accurate and relevant “gamma corrected” method and with tolerance levels that are not based on a moving % (their method still uses the traditional 10 – 90% variable tolerance levels). We discussed why the traditional method is not as accurate in our article linked above.
In the spec the overshoot (on transitions from dark to light shades) needs to be less than or equal to 20%, or for undershoot (transitions from light to dark shades) needs to be less than or equal to 15%. These are in our opinion too high values and leaves the door open for certification under this new programme which is supposed to include low overshoot errors, when a screen might still have very noticeable and distracting overshoot in practice. 20%+ overshoot in our testing has always been considered “red” on our tables and definitely represents visual and obvious overshoot artefacts. We would argue that anything >15% is a real problem so at the very least we believe the overshoot in this new testing criteria should be capped to that same 15% as the undershoot. Why is it ok to have 20% on the rise times where light halos would appear and only 15% on the fall times (dark halos)? If you want to actually make the certification more meaningful when it comes to representing low overshoot, it should really be 10% or lower.
There is another problem with this in that using any % for an overshoot calculation is not always reflective of real-world perceived visual artefacts, and is a moving number dependent on the range of the transition. We talked about this a lot more in this article if you want to know more about why using a % overshoot is flawed, but we have since moved to a far more meaningful and reliable RGB value overshoot for our testing. A percentage just doesn’t really make sense and is a legacy approach. We’d love to see VESA take this in to account and move away from %.
Additionally, within their FAQ they have the following:
For the G2G overshoot/undershoot tests, are you testing at one refresh rate or multiple refresh rates?https://www.adaptivesync.org/faq/
When running in Adaptive-Sync mode, the refresh rate (i.e., the speed at which the data is transferred, frame by frame, to the display) and the speed at which the display scan out is occurring is always at maximum refresh rate. When frames are being updated at less than the maximum refresh rate of the panel, this is not because the panel is running any slower, but because the vertical blanking interval (VBlank) timing between frame to frame has increased. Therefore, there is no reason to test G2G/Overshoot/Undershoot at anything other than maximum refresh rate as that’s the only rate the panel will be operating at when in Adaptive-Sync mode. If you were to exit from Adaptive-Sync mode and change the display timing to a fixed rate timing, then and only then does the display clock rate and scan-out time change, at which point different G2G performance may occur. However, this is outside of the Adaptive-Sync mode and not included within the VESA Adaptive-Sync Display test.
This is not what is experienced in real usage in many cases, you will often see G2G figures and especially overshoot levels vary depending on the active frame rate within a VRR situation. True, some adaptive-sync displays have a fixed G2G figure across the range, but if that is the case then the overshoot level will increase as the refresh rate lowers. That’s one of the reasons why NVIDIA developed variable overdrive for G-sync module screens, and why some manufacturers also look to develop this technology for adaptive-sync screens. That deliberately reduces G2G response times as refresh rate lowers in order to control overshoot. There is varying performance in VRR situations across the VRR range on these screens, it is a bit strange how VESA claim there isn’t.
Dell and LG have some monitors already that have been certified
According to Seok Ho Jang, Vice President in charge of IT Development Division at LG Electronics, “We believe that with VESA launching its Adaptive-Sync Display standard in the rapidly growing gaming market, we can expect to see even greater innovation in the gaming monitor categories. We are proud that the LG UltraGear™ brand will be involved from the very beginning with the acclaimed LG UltraGear 27GP950 and 27GP850 models, the first-ever monitors to receive VESA AdaptiveSync Display certification. LG also has new 2022 models on the way, which we believe will not only meet the high standards demanded by VESA’s performance tests, but are also well equipped to satisfy the expectations and diverse needs of today’s consumers.”
There is a list of certified products available on the VESA AdaptiveSync website here
Do we really need another certification scheme?
This all sounds like a good thing on the face of it – more stringent testing for VRR performance including rules around response times, overshoot and problems like flicker are a good thing. But do we really need another VRR performance certificate? We already have NVIDIA’s G-sync Compatible scheme, which is highly regarded in its testing criteria and methods. In addition AMD only fairly recently (Jan 2020) updated their FreeSync testing and certifications and brought in their new FreeSync Premium and FreeSync Premium Pro tiers for instance. There’s also the HDMI-org VRR that’s part of the HDMI 2.1 standard as an optional feature – it’s not a certification as such, but a technology that may be supported on some screens.
Does this mean we’re doing to see monitors with a mix and match of different certifications, some from NVIDIA, some from AMD, some from VESA? Does it mean some displays will have 2, 3 or maybe even 4 of these logos and certifications? What about when you add on all the other logos like DisplayPort, HDMI, DisplayHDR and so on?
What makes this potentially more problematic is that the naming scheme VESA have selected is so closely linked to the technology, it could become very confusing for consumers. Their press release even had to point this out:
Adaptive-Sync (with a hyphen between Adaptive and Sync) is used for explaining Adaptive-Sync operation and Adaptive-Sync protocols, as well as used to refer to the Adaptive-Sync Compliance Test Specification (Adaptive-Sync CTS). AdaptiveSync (without either hyphen or space) is used to represent the VESA Certified AdaptiveSync logo program. Adaptive Sync (with space between Adaptive and Sync) is a generic term used to refer to variable refresh rate.
Given adaptive-sync (the technology) has been around for 8 years, many displays will mention their support for this technology. You will now need to consider whether it has an added “AdaptiveSync” logo and certification (without the hyphen in “adaptive-sync”) to get some added re-assurance around performance. Or instead maybe you’d look for NVIDIA or AMD certifications as we’ve discussed above.
Additional MediaSync Display Certification
In addition to the AdaptiveSync certification discussed above, VESA also announced the new “MediaSync” scheme which is designed to certify displays for jitter-free media playback supporting all international broadcast video formats. There is no performance tier associated with this logo since the emphasis of product certification is on the absence of jitter and flicker rather than high frame rate.
In addition to the logo-specific tests above, all qualifying devices must meet the following specifications that apply to all logo performance tiers:
The MediaSync Display logo performance tier is designed to ensure that displays meet a high level of quality optimized for media playback, suitable for media that uses any of the 10 most-common video frame rates, which range from 23.976 to 60 Hz. This logo performance tier eliminates video frame dropping, and 3:2 pull-down jitter and other sources of jitter, while meeting its mandatory flicker performance level to make the display visually flicker free.
At the time of writing there are no displays listed on VESA’s website with MediaSync certification.
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