[vdr] Re: choosing a FF card

[Rainer Zocholl <UseNet-Posting-Nospam-74308-@zocki.toppoint.de>]

(Ian Molton)  09.02.05 15:55


>Tony Houghton wrote:

>> Too large for what? ICBW, but my understanding is that if a device
>> is outputting 576 lines in PAL, the height is fixed by the TV and
>> can't be controlled by the device, except that it can probably be
>> shifted up and down a bit. Then the device has to fill the
>> horizontal field, including overscan, to make sure the aspect ratio
>> is correct.

>The overscan is the part of the picture thats displayed offscreen such
>that blooming and other distoprtions present in the garbage TV tubes
>we have dont encroach so visibly on the picture.

>The amount of overscan is determined by the timings of the video mode
>you present to the TV, not the number of pixels per row or number of
>lines. with analogue TVs (or monitors) there isnt any defined 1:!
>mapping of pixels on screen to pixels in the framebuffer and its not
>uncommon for poorly adjusted TVs and monitors to have half pixel
>overlaps or worse between pixels, etc.

>> If a graphics card is showing an 800x600 desktop on a TV with no
>> overscan, then it's probably scaling to fewer than 576 lines. If
>> you're only concerned with video, then I think you'll find the
>> amount of overscan is the same as you'd get from a DVD player or
>> STB.

>Im displaying a pal res output, 576 lines. but the amount of overscan
>in the timings produced by my board is both too great and
>unadjustable.

Hm, i wonder why so many 50cm "LCD-TV" for PAL have only 640x480 pixels.
For NTSC 640x480 seems to be sufficent, but for PAL with its 756x576
matrix: Isn't that fooling customers to sell such LCD-TVs in PAL-countries?

Or how to they do the "trick"?



Rainer