What stretch method the "DS" mode uses by default?

[TheManuel]

I have been setting up a bunch of emulator to run on a cabinet setup and ZSNES has always been my choice for SNES. I have been trying to get all of them to stretch the graphics so that they cover the whole screen.
On most emulators, when stretching, I have to settle for either the modes that add odd pixels to the graphics in order to stay very sharp (but looks like crap) or the bilinear interpolated modes which preserve the orginal shape and proportions of the graphics but add blur.

One thing I noticed is that ZSNES provides the best compromise between the two. When I select 640x480 DS with no filters, the graphics look right and the blur is minimal.

What is the stretch method employed by ZSNES in that video mode?
Is it something special or perhaps I might have missed it when playing around with the settings of other emulators like Nestopia?

[grinvader]

Someone should gather all the ddraw blur posts into a dedicated forum, just for shit and giggles. It's like 30% love it, 50% hate it with a fiery passion, and the rest use another filter.

[creaothceann]

On most emulators, when stretching, I have to settle for either the modes that add odd pixels to the graphics in order to stay very sharp (but looks like crap) or the bilinear interpolated modes which preserve the orginal shape and proportions of the graphics but add blur.

Well, it is either one or the other. At least on PC monitors/graphic cards, which have a fixed horizontal resolution.

What is the stretch method employed by ZSNES in that video mode? Is it something special or perhaps I might have missed it when playing around with the settings of other emulators like Nestopia?

If you're not using the "interpolation" filter of ZSNES then it's simply the blur added by the graphics card. ZSNES sends a 256x224 bitmap and simply tells the card to stretch it.

[leilei]

I remember this forced interpolation on Geforce cards. >_<

3dfx/PowerVR/Radeon does it differently, it's still filtered but it seems to be scaled 4x before that so it's a bit more blockier. Interpolation option works.

[paulguy]

Doesn't DS just pixel double on both axes by default (nearest neighbour) to 512x448 then allow the video card or whatever to bring it up the rest of the way?

[grinvader]

No.

[Johan_H]

That's pretty much what I thought it did too. How is the sharpness achieved then, and why does D make things sharper?

[TheManuel]

Sounds like DS follows a similar approach to MAME with DirectDraw and Hardware Stretch enabled.
Apparently, other emulators don't have this option and simply do the scaling themselves.
That's too bad.

I understand that fixed resolution monitors will force you into some sort of compromise. I simply think that ZSNES's DS offers the best one.