Variable refresh rate (VRR) refers to a dynamic display that can continuously and seamlessly change its refresh rate without user input. A display supporting a variable refresh rate usually supports a specific ''range'' of refresh rates (e.g. 30 Hertz through 144 Hertz). This is called the ''variable refresh rate range'' (VRR range). The refresh rate can continuously vary seamlessly anywhere within this range.

Purpose

On displays with a fixed refresh rate, a frame can only be shown on the screen at specific intervals, evenly spaced apart. If a new frame is not ready when that interval arrives, then the old frame is held on screen until the next interval (stutter) or a mixture of the old frame and the completed part of the new frame is shown (

tearing Tearing is the act of breaking apart a material by force, without the aid of a cutting tool. A tear in a piece of paper, fabric, or some other similar object may be the result of the intentional effort with one's bare hands, or be accidental. Un ...

). Conversely, if the frame is ready before the interval arrives, then it won't be shown until that interval arrives. Variable refresh rates eliminate these issues by matching the refresh rates of a display to be in sync with the

frame rate Frame rate (expressed in or FPS) is the frequency (rate) at which consecutive images (frames) are captured or displayed. The term applies equally to film and video cameras, computer graphics, and motion capture systems. Frame rate may also be ca ...

from a video input, making the display motion more smooth. Although VRR is strongly associated with

video games Video games, also known as computer games, are electronic games that involves interaction with a user interface or input device such as a joystick, game controller, controller, computer keyboard, keyboard, or motion sensing device to gener ...

due to such content having unpredictable, discontinuous frame rates and thus most maximally benefit from the technology, VRR is also useful as well even for media whose frame rate is fixed and known in advance, such as movies and video, by being able to automatically match the refresh rate to the various frame rates used as industry standard (24, 30, and 60 FPS), again eliminating screen tearing. In this regard, VRR can save power by not needlessly refreshing the display when no new frame is being pushed out; furthering this, VRR also has use in

power management Power management is a feature of some electrical appliances, especially copiers, computers, computer CPUs, computer GPUs and computer peripherals such as monitors and printers, that turns off the power or switches the system to a low-power stat ...

, by temporarily lowering the refresh rate of a display during instances when there is little movement on the screen to save power.

History

Vector displays A vector monitor, vector display, or calligraphic display is a display device used for computer graphics up through the 1970s. It is a type of CRT, similar to that of an early oscilloscope. In a vector display, the image is composed of drawn li ...

had a variable refresh rate on their

cathode ray tube A cathode-ray tube (CRT) is a vacuum tube containing one or more electron guns, which emit electron beams that are manipulated to display images on a phosphorescent screen. The images may represent electrical waveforms ( oscilloscope), pictu ...

(CRT), depending on the number of vectors on the screen, since more vectors took more time to draw on their screen. More recently, since the 2010s decade, raster displays gained several industry standards for variable refresh rates. Historically, there was only a limited selection of fixed refresh rates for common display modes.

Implementations

Variable refresh rate display technologies include several industry standards and proprietary standards: * AMD FreeSync *

Nvidia G-Sync G-Sync is a Proprietary software, proprietary adaptive sync technology developed by Nvidia aimed primarily at eliminating screen tearing and the need for software alternatives such as Analog television#Vertical synchronization, Vsync. G-Sync elimi ...

VESA Adaptive-Sync press release

HDMI 2.1 Variable Refresh Rate (VRR)

Apple ProMotionQualcomm Q-Sync

References

External links

TestUFO Animation: Variable Refresh Rate Simulation
Graphics hardware Temporal rates {{compu-graphics-stub