AMD FreeSync 2 Brings Latency, LFC and Color Space Requirements
Subject: Graphics Cards, Displays | January 3, 2017 - 09:00 AM | Ryan Shrout
Tagged: srgb, lfc, hdr10, hdr, freesync 2, freesync, dolby vision, color space, amd
Since the initial FreeSync launch in March of 2015, AMD has quickly expanded the role and impact that the display technology has had on the market. Technologically, AMD added low frame rate compensation (LFC) to mimic the experience of G-Sync displays, effectively removing the bottom limit to the variable refresh rate. LFC is an optional feature that requires a large enough gap between the displays minimum and maximum refresh rates to be enabled, but the monitors that do integrate it work well. Last year AMD brought FreeSync to HDMI connections too by overlaying the standard as an extension. This helped to expand the quantity and lower the price of available FreeSync options. Most recently, AMD announced that borderless windowed mode was being added as well, another feature-match to what NVIDIA can do with G-Sync.
The biggest feather in the cap for AMD FreeSync is the sheer quantity of displays that exist on the market that support it. As of our briefing in early December, AMD claimed 121 design wins for FreeSync to just 18 for NVIDIA G-Sync. I am not often in the camp of quantity over quality, but the numbers are impressive. The pervasiveness of FreeSync monitors means that at least some of them are going to be very high quality integrations and that prices are going to be lower compared to the green team’s selection.
Today AMD is announcing FreeSync 2, a new, concurrently running program that adds some new qualifications to displays for latency, color space and LFC. This new program will be much more hands-on from AMD, requiring per-product validation and certification and this will likely come at a cost. (To be clear, AMD hasn’t confirmed if that is the case to me yet.)
Let’s start with the easy stuff first: latency and LFC. FreeSync 2 will require monitors to support LFC and thus to have no effective bottom limit to their variable refresh rate. AMD will also instill a maximum latency allowable for FS2, on the order of “a few milliseconds” from frame buffer flip to photon. This can be easily measured with some high-speed camera work by both AMD and external parties (like us).
These are fantastic additions to the FreeSync 2 standard and should drastically increase the quality of panels and product.
The bigger change to FreeSync 2 is on the color space. FS2 will require a doubling of the perceivable brightness and doubling of the viewable color volume based on the sRGB standards. This means that any monitor that has the FreeSync 2 brand will have a significantly larger color space and ~400 nits brightness. Current HDR standards exceed these FreeSync 2 requirements, but there is nothing preventing monitor vendors from exceeding these levels; they simply set a baseline that users should expect going forward.
In addition to just requiring the panel to support a wider color gamut, FS2 will also enable user experience improvements as well. First, each FS2 monitor must communicate its color space and brightness ranges to the AMD driver through a similar communication path used today for variable refresh rate information. By having access to this data, AMD can enable automatic mode switches from SDR to HDR/wide color gamut based on the application. Windows can remain in a basic SDR color space but games or video applications that support HDR modes can enter that mode without user intervention.
Color space mapping can take time in low power consumption monitors, adding potential latency. For movies that might not be an issue, but for enthusiast gamers it definitely is. The solution is to do all the tone mapping BEFORE the image data is sent to the monitor itself. But with varying monitors, varying color space limits and varying integrations of HDR standards, and no operating system level integration for tone mapping, it’s a difficult task.
The solution is for games to map directly to the color space of the display. AMD will foster this through FreeSync 2 – a game that integrates support for FS2 will be able to get data from the AMD driver stack about the maximum color space of the attached display. The engine can then do its tone mapping to that color space directly, rather than some intermediate state, saving on latency and improving the gaming experience. AMD can then automatically switch the monitor to its largest color space, as well as its maximum brightness. This does require the game engine or game developer to directly integrate support for this feature though – it will not be a catch-all solution for AMD Radeon users.
This combination of latency, LFC and color space additions to FreeSync 2 make it an incredibly interesting standard. Pushing specific standards and requirements on hardware vendors is not something AMD has had the gall to do the past, and honestly the company has publicly been very against it. But to guarantee the experience for Radeon gamers, AMD and the Radeon Technologies Group appear to be willing to make some changes.
NVIDIA has yet to make any noise about HDR or color space requirements for future monitors and while the FreeSync 2 standards shown here don’t quite guarantee HDR10/Dolby Vision quality displays, they do force vendors to pay more attention to what they are building and create higher quality products for the gaming market.
All GPUs that support FreeSync will support FreeSync 2 and both programs will co-exist. FS2 is currently going to be built on DisplayPort and could find its way into another standard extension (as Adaptive Sync was). Displays are set to be available in the first half of this year.
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