Motion tests

What rolling buffer is

Newer DLP controllers, such as the DLPC8445 and DLPC8455, don't wait for the whole frame before putting it on the chip. They switch to the new frame in a band that runs from top to bottom. That cuts input lag, mostly at the top of the screen, but each band switches at a different point in the colour sequence, so some of its colours still come from the old frame and some already from the new one. On a still picture you won't notice it. On a moving high-contrast edge it shows up as a coloured fringe: a thin red, green, blue or magenta line, sometimes with a small break. Unlike the rainbow effect, which your own eye movement creates, the rolling-buffer fringe is in the picture itself: you see it with a steady gaze too.

How to watch

Show the page on the projector from a PC or media player, full screen, at native resolution, and sit where you normally watch. Follow the shape with your eyes. The fringe sits on the edges that lie across the motion: when the shape moves sideways, look at its left and right edges; when it moves up and down, look at the top and bottom. Start slowly. At high speed the shape is a blur and the fringe is harder to see, so the default is a calm 240 px/s. The speed is set in pixels of the actual screen per second (1x is 120 px/s). The shape moves by a whole number of pixels per frame, so the readout below the pattern shows the step at your refresh rate and the speed that results.

Scenes

One shape runs along the chosen path. Mirror splits the screen into black and white halves with the same shape mirrored in each, so you can compare a white edge on black with a black edge on white. Two shapes move sideways on the left and up and down on the right, which shows both edge pairs at once. Three speeds runs the shape at half, one and two times the set speed side by side, sideways or up and down only. Credits and News ticker show the effect on text, the way you'll meet it in movies and on TV. Rotation shows edges at every angle at once: the fringe moves around the shape as its direction of travel turns. If you also want to check the rainbow effect, use the Rainbow Test.

Mouse: click the pattern to pause, double-click for fullscreen. Keys: left / right arrows sideways, up / down arrows up-down, D diagonal, R rectangle, S screensaver, M next scene, + / - speed presets, space pause, F fullscreen.