Scanlines and stutter

[Yarb]

I've been trying to get a good arcade look on the 21" KDS monitor in MAMA and finally found a setting that looks good but the audio in some games stutters set this way in MAME 32 Win XP:

Stretch with Hardware off
Scanlines 50%

My system has plenty of horsepower and RAM so I'm stumped

Any suggestions

[MameFan]

Both of these settings  basically use TONS of CPU processor to draw the video screen before sending it to the video card.

You're easily pushing through 2x (actually 4x if you consider 2x+2y = 4x) or 3x (9x) data thru the AGP bus to the video card.

Therefore you're not having the dedicated processor of the video card doing the stretching, you're having the CPU do it all, which takes away power for things like sound, or overloads the bus, net result the same: other things get delayed as video has priority.

Basically lets say you have a 320x200 game you're playing, like Defender.  Normally Mame sends this 320x200 to the video card.. That's 64,000 pixels per 1/60th of a second.

The video card takes this and scales it to fit the best resolution.. Usually 640x480 (doubles the width and height of each pixel [4x])  Some might go to 1024x768 and triple the width and height [9x], but "soften" the edges to give a smoother view rather than large square pixel blocks.)

However as of yet video cards can't add in "scanlines" without being fed the data directly (e.g. most can't draw a mask over the picture with a single command, they must be fed each bit).

Therefore when you turn off the hardware stretch and enable scanlines, the computer CPU determines "half brightness" between each and every vertical row's pixel to draw in a pixel under it.  Assuming it's having to at least double the size of the screen to 640x400 (though most go to 1024x768), you now are sending 256000 pixels thru every 1/60th of a second.. Thats FOUR TIMES the amount of data going to the bus.  Plus the cpu time to calcuate the "halfway" pixel on each scan line row.

That's why it's slow.

Only ways to improve it:
1) Get more CPU horsepower
2) Get a video card that runs at 4x AGP if it doesn't already
3) Ensure your motherboard has 4x AGP bus.
4) Deal with hardware stretching and no scan lines.  It gives a soft look on most newer (e.g. GeForce2 or better) cards, almost mimicing a slightly off-focus arcade monitor that has drifted a bit from age.

[Yarb]

I can't get much more horsepower, I recently did a UT-2003 is coming out soon upgrade.

Athlon 2000
640MB RAM
ABIT KR7A-133R MB with AGP 4X
Gforce 4 TI 4400
Win XP
SB Live (Old I know)

It seems that it should be able to manage it but I'm not having alot of luck messing with settings.

Yarb

[rgardjr]

I was having some performance problems with my cabinet and tracked it to the wifi network card that I had plugged.  Now the card isn't plugged in unless I'm actually using it.  Just a thought.
Rick

I can't get much more horsepower, I recently did a UT-2003 is coming out soon upgrade.

Athlon 2000
640MB RAM
ABIT KR7A-133R MB with AGP 4X
Gforce 4 TI 4400
Win XP
SB Live (Old I know)

It seems that it should be able to manage it but I'm not having alot of luck messing with settings.

Yarb