thanks for replying, i still have some questions though.
here goes..
yeah that sounds right that i could avoid this effect by setting the calibration width exactly to the screen edges and raising the top instead. but that doesn't really solve the problem i think, just move it to the other side, because if i now play some imaginary 9:16-video or somesuch it will now lose it's top and bottom pixels. (same thing if i were to use zoom i think).
(jmarshall @ oct. 20 2003,22:49 Wrote:if you are using 720x576 pal, and have the calibration all set to (0,0) -> (0,0) so that you are getting all the pixels, then a 4:3 aspect ratio movie (such as an avi with a frame size of 640x480) will be shown with size 702x576. this is the correct frame size (actually it's 702 54/59 pixels wide) that defines the pal 4:3 picture. note that the black bars (around 8 and a bit pixels either side) at the sides of the picture will not be seen, as most tv's have overscan of around 16 pixels either side.
doesn't this mean that the same problem i was trying to describe will occur? if i have no calibration ((0,0)->(0x0)) the 4:3 640x480 .avi-file will indeed look correct as you say, because the overscan pixels at the sides will not be used. but if i play a 16:9 640x360 .avi, it will fill out the width and now be using those overscan pixels. but i don't want the actual picture from the 16:9 movie to be any vider than the 4:3 one because then i'm missing pixels that i'd rather have visible.
what i'm trying to get at i think is that your aspect ratio calculations are just fine, but the calibration needs to be altered to calibrate the visible 4:3 area instead of adjusting this slightly too wide pal area.
another thing with the current calibration is that i find it rather counter-intuitive. i think the cause is this: what i'm really calibrating is position (x,y) and size (just size, not width and height). which is three variables. but the calibration arrows define four variables (top x,y bottom x,y). so when i move the bottom arrow i can affect where the top of the picture is which i found very confusing.
the aspect ratio calibration that you suggest sounds like a good idea, but as you say it probably isn't needed as most tv's most likely have a correct ar already.
i haven't actually tried your suggestions though so it is quite possible that i'm still completely wrong, but i'll try it out tonight after work. thanks for your time anyway.