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-   -   KVCD: Shifting image? (http://www.digitalfaq.com/archives/encode/4937-kvcd-shifting-image.html)

J-Wo 08-08-2003 08:51 AM

KVCD: Shifting image?
 
Today I was playing around with an overscan of 3 in my 528x480 encodes, and noticed on my 20" TV that the image is actually shifted to the right a bit, i.e. I can see a black border on the left of my screen. So....

1) What kind of lines could I add to shift the image to the left by x pixels?

2) So long as my TV can display the image without any visible borders, does increasing overscan to 3 actually improve anything in terms of video quality?

Thanks!

Dialhot 08-08-2003 10:08 AM

That is a very bad idea to add a shift on one side for matching your TV set default. Bescause that is a default, or if you prefer, a bad setting. Normaly the picture is supposed to be centered on the tube.

If you modify your KVCD, you won't be abble to watch them on other TV set. And more, even on your actual set, problems should occur in the future (nothing is permanent with electonics).

The best is to not use overscan over 2, even if your set is abble to display it today.

J-Wo 08-08-2003 11:26 AM

Good point re: not being able to watch my discs on other TVs. Yes it is a bad default on my TV and it really is too bad that there's no horizontal shift on the unit. Mind you the unit is probably a good 15+ years old, but it's a sturdy Toshiba that has stood the test of time and still has a great picture. If not a tad shifted... :wink:

dazedconfused 08-08-2003 01:54 PM

Hey J-Wo,

I thought that this post might interest you if you haven't already seen it: http://www.kvcd.net/forum/viewtopic.php?t=5452 . What Rendalunit describes there could probably be used to accomplish what you originally asked (although as Dialhot pointed out, it's probably not the greatest idea compatibility-wise :wink: ). As a general rule of thumb, most people probably shouldn't use a blocks-overscan setting higher than 1 for 352x240/288 and 352x480/576 resolutions, or a setting higher than 2 blocks for any resolutions above that. Most peoples' TVs won't display these sorts of "shifting" or "black borders on one side of the screen" problems if you stick within those limits. Some people may be able to get away with higher overscan settings on their TVs...more power to 'em...but they'd better hope their current TV never dies or they may find themselves staring at "shifted" pictures on their next TV set.

Of course, some people don't like using overscan at all and prefer the overlap method to retain the full height of the picture...but that argument is a whole 'nother ball of wax :lol: . (personally, I prefer overscan for the extra compression it gives :wink: ...but to each his own).

-d&c


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