Display timewarp

[ddrueding]

Interesting. When I get my gaming machine set up again I'll run some tests.

 

[sdbardwick]

No, Memory typically will put several bytes or words worth of data on the bus while only requiring one address setup operation. Typically this means you store sequential horizontal pixel data in order. So when you want to read it you get high bandwidth with minimal setup operations. However, when you want to read the data in a different manner, say for example vertically, you need a setup operation after every byte or word since you're not interested in the data in the following byte or word. This makes the effective memory bandwidth much less because there are many times more setup operations.

Not sure there would be any change to memory access. I'd say you just go from vertical refresh to horizontal refresh. On a 1920x1080 monitor changing the physical orientation of the display does not change it from 1080P to 1920P.

 

[LunarMist]

My 2005 1200x1600 monitor changes orientation when the display is rotated. It seemed fine to me other than the few seconds of changeover. Surely by now there should not be a problem?

 

[sdbardwick]

I'm not being clear. On my systems the VSYNC frequency does not change when I change from landscape to portrait (I guess it could on other systems, but that seems to add unnecessary complexity). The top to bottom vertical refresh simply becomes right to left horizontal refresh after rotating the monitor 90 degrees clockwise.

 

[Stereodude]

Not sure there would be any change to memory access. I'd say you just go from vertical refresh to horizontal refresh. On a 1920x1080 monitor changing the physical orientation of the display does not change it from 1080P to 1920P.

No, but the image on the screen is rotated relative to the orientation of the video output signal. That rotation has to occur somewhere. Rotating an image means means at some point your reading data from memory the "wrong way".

 

[sechs]

No, but the image on the screen is rotated relative to the orientation of the video output signal. That rotation has to occur somewhere. Rotating an image means means at some point your reading data from memory the "wrong way".

I think that's the point where you've rotated the screen and it blinks for a second.

If you turn your head ninety degrees to the left, it doesn't take you any longer to see the image....