TV-Out and Dosmame

[Hornpipe2]

My cab has a PC with some ATI Rage (composite [RCA] video out) hooked to a 19" NTSC SDTV oriented vertically.  Mame version is dosmame 0.106.  OS is Freedos 1.0.  I have it working and images display, which is good.  However, I have a strong suspicion that I've not configured things to get an ideal display.

I'm looking through the various tweak/notweak, vesa, and resolution xyd settings in the mame.cfg file, but it ends up just confusing me.  I have a suspicion that I'm actually running everything at a virtually stretched 640x480 image and putting that to the TV.  Seems to me I should be able to instead get mame to pick the exact resolution and let the card do the scaling...?

Ideally I want my TV to (in order of importance)
* replicate the aspect ratio of the original game
* run at the exact resolution of the original game
* failing that, run at the next lowest supported resolution (e.g. spray everything on a 320x240 canvas and let -stretch take care of the rest)
* do these things as efficiently as possible.

Hopefully that makes sense...?  I'm new to configuring this stuff so maybe I'm confusing, I hope not.  Probably what would be best is: if anyone out there is running dosmame on a TV, I'd like to see your video config sections.

[MonMotha]

Unfortunately, TV outputs on video cards do not normally support being fed TV timed input.  They want to take VGA (or SVGA, or whatever) timings and run them through a pixel masher to get something TV compatible out of them.  Even if they do accept TV compatible timings, they will still often run them through the pixel masher anyway, negating any benefit of native game timings.

However, here's a set of ideal timings for televisions:
http://www.linuxis.us/linux/media/howto/linux-htpc/video_card_configuration.html
(Scroll down for a set of X11 compatible modelines that you can use to back out everything you could possibly want in terms of video timings).

Really, if you're close, most analog TVs are fairly forgiving.  Best to match the native output of the game if you can.

You will likely get better quality if you do native timed RGB output (which most video cards these days ARE capable of) and use an outboard RGB to TV encoder.  This will ensure that there's no nasty scaling, framerate conversion, unwanted interlacing, etc. going on like most TV outputs onboard video cards will do.  I've had extremely good luck with this technique: S-Video approaches the quality of RGB, though composite tends to still look pretty awful (no way around that one).

Our good friend Yaton has a cheap (though quality largely unknown - the main chip on the board is OK) one:
http://www.arcademvs.com/ARCADE_ACESSERIOR.htm (Item A-22)

It appears to be the EXACT same thing as is sold branded Wei-Ya at jammaboards.com for $15 more (though shipping may be less, there).

[Hornpipe2]

Thanks for the advice.  That makes a lot of sense about the "pixel masher", and I can see how I pretty much get no control over the output from the TV-Out.  I will consider a VGA -> TV box but it's not likely I'll make the switch, since I'm more interested in finishing the project with what I've got on hand - and I do at least have images on the screen.

However, this brings a new round of config questions.  Since I can basically expect the GFX card to turn any VGA-compatible signal into a TV-compatible one, I want to pick Mame VGA outputs that get the most performance.  (It's a low-spec machine and gets pretty close to full-speed but drops frames sometimes.)  So I think I'll want to play with "tweak" modes.  Is there a guide somewhere that explains these a little better?

I think by default Dosmame tries to use VESA to do the video work, but this can be disabled if I want.  It seems to me that if Mame is emulating a 288x224 display and using -stretch (through VESA) to create a  320x240 VGA signal, I could save the machine some work by just outputting the 288x224 signal in the first place?  Essentially what I would want to do is have Mame pump images to the card at game resolution, and let the GFX card figure out how to make that into a TV image.  Make sense?

[siastbill1]

Your TV out card is probably trying to output at a fixed resolution (like 640x480), regardless of what type of input you feed it. If your CPU can rescale a low arcade resolution (like 320x240) to 640x480 faster than the card can, then you should do your resizing in software. If your card can do it faster, then don't bother doing any software resizing.

That being said, it may be that the card still likes to mess with input, even if it is ideal (ex. still performs processing on 640x480 input even if mame is outputting at 640x480). In this case, there is nothing that you can really do, cause it's the TV functionality of the card that is the bottlneck.

I performance tested a Nvidia Geforce 2 in Dos TV out mode VS Windows TV out mode, and I got a performance boost when going to Windows (undoubtedly because of the Direct X accelerated Windows drivers).

Because I wanted to stick with dos, I ended up dropping the TV out idea entirely, and running advancemame with a real arcade monitor. That way, I could output the exact resolution of the game straight to the monitor, without having to worry about scaling and the like. The speed increase was also substantial over dos mame and TV out.

In the end, you are gonna have to performance test your card using various mame resolutions to see if there is an improvement.

[Hornpipe2]

I went out to the garage and messed with it a bit but not much luck.  There was no noticeable performance boost choosing (tweak=yes) over (tweak=no, vesa=vesa3), and the picture didn't look any better.  I think MAME is already doing a good job picking the appropriate resolution anyway (resolution=auto), because there was also no noticeable difference between stretch=yes and stretch=no with tweak=off.

Incidentally tweak=on let my card go over 60hz refresh (Galaga at 60.606060) which caused the TV-Out to freak and fail to display properly - rate was too high for my TV, is there a way to cap rate at 60hz?  So it seems VESA3 is the safe alternative.  I get a picture with every game I've tried at least.

I'm left with more questions as to what exactly the tweak mode is supposed to be used for, but it doesn't look like it is supposed to be used by me : )

[Hornpipe2]

As a followup (not like anybody cares ) I found a copy of Scitech Display Doctor 6.53 and gave it a shot.  It doesn't play nice with the FreeDOS EMM386 driver, and even when I disabled that, SDD's vesa driver broke the TV-Out features on the card.  It would have been nice but I guess fate was against me.

In any case though I did find the included VBETEST app useful... it was able to show me that my card actually supports only vesa2, and now I have a list of supported resolutions as well.  So I can make informed choices about resolution and especially vectorres.

[Beretta]

i dont think that card will help him out of the box..

it looks like it's setup to run arcade PCB's on a TV, which is a pretty nifty idea in it self.

that is to say it's for hooking up CGA -> tv, not VGA -> tv
although i suppose it would work fine if you was putting out a low freq like you was gonna hook it to a arcade monitor.