Vertical synchronization

From Free net encyclopedia

Vertical synchronization refers generally to the synchronisation of an event with the vertical blanking interval. Generally video displays are refreshed sequentially and on older CRT based displays, a short delay is required between updating the lowest horizontal line of the display and returning to refresh the highest. This delay, which is preserved by more modern display equipment, gives an opportunity in computer graphics to alter the contents of a framebuffer without visible graphical errors such as partially redrawn graphics or page tearing (when the top part of the display shows part of one frame and the bottom part shows of another).

Computer games often allow vertical synchronisation as an option, but is sometimes disabled because it has the effect of limiting frame rates to the monitor's refresh frequency creating a psychological disadvantage although not a visible one. Games that use double buffering but cannot keep up with the refresh frequency are usually limited in frame rate to a divisor of the refresh rate, but this can be avoided by the use of more buffers albeit at the cost of more video memory.

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