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The New Video Landscape
A whole pile of stuff has changed during the 0.106 development cycle, and though we are a few weeks away from a real 0.107 release, it's probably time to sit down and have a little heart-to-heart about the video options.
Since its inception 9 years ago, MAME's video system has defaulted to a mode where it tries to change resolutions on you. And since the first port of the core to Windows 5 years ago, it has defaulted to using your graphics card to stretch the video to that resolution.
I'm sure a lot of you out there have taken a lot of time to tweak the current set of video options to make them work the way you like. But every once in a while, you need to take a step back and re-evaluate the situation. The current video system has been in place for 5 years now without much substantial change. And with the recent rewrite, you're almost certainly going to want to rethink the way you have things configured.
At the highest level, there are really three different ways you can configure
the new system. Placing yourself into one of these three categories will
help you get the initial settings right. From there, you can tweak with
the settings to figure out what works best.
Category 1: Bells and whistles. People who fall into this category
would include anyone with a modern system and a decent video card (decent
in this context means at least 16MB of VRAM and built in the last 5 years
or so -- we're not talking cutting edge here). Any decent video card will
be able to render the simple MAME graphics at pretty much any resolution
without breaking a sweat. Configure your desktop to the video mode you
want (preferably something high like 1024x768 or greater with a high refresh
rate, unless you are running on a fixed-mode LCD, in which case just match
what your LCD panel is), and tell MAME to leave the resolution alone. In
this day and age, there is little reason to switch resolutions at all,
unless you fall into Category 3, below. In this mode, you will have full
access to artwork options, and you'll get your artwork scaled to full resolution
and with full alpha blending effects. Vector games will look crisp, you
can use decent fonts, and you can see a whole lot more of the world when
using the graphics/tilemap viewer. This mode uses Direct3D, so you should
configure yourself like this:
-video d3d -noswitchres [-triplebuffer] [-nofilter]
The -noswitchres option tells MAME to just run at the current resolution.
Although you can let MAME pick a resolution for you, it doesn't really
make much sense in D3D mode, and in fact I may even remove that feature
altogether. To avoid tearing artifacts, I recommend using the -triplebuffer
option as well. Just make sure your monitor's refresh rate is higher than
the game you are running. If you dislike the blurry look of the graphics,
you can specify the -nofilter option to disable bilinear filtering, though
that will produce blocky artifacts. Alternatively, you can use the -prescale
option which is described at the end of this article.
Category 2: Like the old days. I really didn't even want to support
this mode at all, but certain vocal MAMEdevs would have skinned me alive
otherwise. People who fall into this category include those who have weak
systems that worked fine with previous versions of MAME, but who don't
run well with Direct3D rendering. (Note that just because Space Invaders
runs unthrottled at 2000fps with DirectDraw and 1000fps with Direct3D doesn't
mean that Direct3D is going to be a serious issue when playing at a regular
60fps, so if you're unsure, give the Direct3D route a try for a while.)
In this mode, MAME will draw the game screen and artwork at the game's
resolution, just like it did in MAME 0.106 and earlier; however, some artwork
options, such as -artcrop, won't work as you might expect, and some alpha
blending artwork modes (specifically overlays) won't work. MAME will then
use your video card to stretch the video to the proper aspect ratio.
-video ddraw -hwstretch [-switchres] [-triplebuffer]
The -switchres is optional here. If your video card is really ancient and
struggles expanding the screen to fit your desktop resolution, you might
want to turn it on. Again, to avoid tearing artifacts, I recommend using
the -triplebuffer option as well, but make sure your monitor's refresh
rate is higher than the game you are running (-switchres will do that for
you if you use it). If your video card produces blurry pixels which you
don't like, try the -prescale option described at the end of this article.
Category 3: Anal video mode types. These are the guys who have generally
built their own cabinets and set them up with a CRT display where they
have several dozen carefully hand-tweaked video modes that approximate
the original video modes the games ran at. They want MAME to pick that
hand-tweaked mode and use it, drawing one pixel on the screen for each
pixel in the original game. They don't give a whit about artwork or anything
other than the raw pixels going to the right place. Fortunately, you can
still configure MAME for this case as well:
-video ddraw -nohwstretch -switchres [-triplebuffer]
Obviously in this case, the -switchres is required. You also want to disable
hardware stretching, otherwise you won't get that "perfect" 1:1 pixel mapping.
Triple buffering may or may not help.
So, I recommend starting with these initial options and then tweaking from there. One additional option you might want to try in combination with the above is the -prescale option. -prescale takes an integer parameter from 1 to 8, and specifies a magnification amount by which the screen pixels are expanded before they are drawn to the screen. Why is this useful? And how much of a performance impact does it have? Well, that depends on the mode you are running in.
If you are running in Category 1 (-video d3d), then -prescale will use your video card to scale the game graphics up before rendering them to the screen. Depending on the video card, this is usually a small performance hit, but not too significant. The benefit is that each prescale factor reduces the blurriness of the pixels. -prescale 1 is the default, which does no scaling. -prescale 2 will double each pixel, -prescale 3 will triple each pixel, etc. For my money, -prescale 2 is sufficient, but people with super high resolution displays claim that larger -prescale factors work even better.
If you are running in Category 2 (-video ddraw -hwstretch), then -prescale will cause MAME to compose the screen graphics at the specified scale factor. This is unfortunately done in software, but carries the benefit that artwork, fonts, and the graphics viewer can take advantage of the additional resolution to produce nicer results. The end effect is that you will get less blurry pixels, just like the Category 1 case, plus higher quality artwork, fonts, and more visible area in the graphics viewer.
If you are running in Category 3 (-video ddraw -nohwstretch), then -prescale will cause MAME to pick a video mode that is the prescale factor times the raw screen resolution, and then MAME will, in software, compose the screen graphics at the specified scale factor. This has all the advantages of the Category 2 case, except that since there wasn't any pixel blurring to begin with, there is no additional crispness that comes about as a result.
Finally, you may be wondering about effects (and yes, scanlines are an "effect"). Well, let's take the band-aid off quickly:
Effects are not currently present in the video system and are not planned in the short term.
Ouch.
Are they gone forever? It's too early to say for sure. They present some unique problems. It's possible that if they do come back, they will only be available in Direct3D (Category 1) mode. For the next few versions of MAME, try living without them. Certainly, I want the video system as it currently stands to stabilize before even considering it.
I'll try to post a binary for u10 when it's available to let everyone play with the options a bit.