Groovy Mame scrolling issues

[stiegi]

Hello guys!

I have been using groovy mame for a long time and I think the program is really good when you take the effort to dig into it.

My setup is an intel i3 pc dual core with windows xp professional 32-bit, the graphics card is an ati radeon hd 4670, i am using groovy mame 0.149 and a Sony pvm 2053md.

I want to keep it as short as possible. All in all I noticed that the scrolling with groovy mame is really fine but I encountered some issues with some games. As I am not owning a dedicated machine I cannot compare it to the real thing. Perhaps someone can write down how certain games work in his groovy mame setup or can say how it should be on the real machine.

I noticed with some games that there are some "special" scrolling issues even though groovy mame sets the same vertical refresh as the native game.

This is about vertical games - I have mounted the Sony vertically in my self-build mame cab

For example in Commando I noticed that the screen will scroll smoothly up and down when the character moves but as soon as the character moves DIAGONALLY you will see some "microstutter"

Another example would be the game  Legendary wings. In the first part of the game the screen scrolls "down up" which has smooth scrolling. In the second part the scrolling is switched over to horizontally which means the character moves from left to right on the vertical screen. The screen will only move as soon as the character moves - when it does you can see again this microstutter of the screen.

Another game I noticed was starforce - the game itself scrolls more or less smoothly but the stars which scroll in the background always seem to "tremble"

I also noticed it in vs Mario Bros - this is a horizontal game. Its the same as in Legendary wings - the whole screen will have some microstutter as soon as the character starts to move.

Does anyone know why this happens even though groovymame choses the exact refresh rate of the native game? Does the original hardware behave the same? Or has it got something to do with the monitor which is not able to sync exactly to the signal of the GPU or because of slightly changing vertical refresh rates due to varying game speed during gameplay?

regards,
Alex

[Calamity]

Post a log of the games that don't work fine.

[adder]

hello stiegi, regarding commando I thought that was normal in that game, ie. with the soldier if you run straight up the screen it is very smooth in scrolling, but if you run diagonally up (so now, not running as fast upwards), your soldier is moving both vertical and horizontally, and the result is not so smooth.

but for other (lots) of games in mame which have the odd hiccup or stuttering (often because the game is pushing its hardware quite hard), you can use the overclocking mame feature to get smoother results. to do this you set the option cheats 1 in mame.ini, and then when you load mame, go into the slider controls menu and overclock the cpu of the game in question.

there are lots of games which benefit from this. a common example is metal slug. on the arcade pcb (so also in mame) there is a lot of slowdown on that game but overclocking makes it run smooth and more consistent. double dragon is another example.

note: some people say overclocking in mame may cause the game to play 'differently' (eg. game logic), or cause problems. so that is something to keep in mind (personally I use it quite often though, and havnt noticed anything bad for doing so.  yet   )

[stiegi]

Hello!

Thx adder for the tip - I am going to give it a try. I have always had the option cheat not activated. It is really hard to find out why some games have this odd behaviour. I am going to post some more games it is not a big deal but when you are into the emulation stuff you are gettting more and more critical and you want to have it "perfect". When someone showed me my mame arcade cab as it is now it would have totally blown my mind - donīt get me wrong itīs still amazing now 

In my opinion smooth and accurate graphics and minimum input lag are the two most important things when it comes to emulation otherwise the "illusion" of the legendary old games will get lost.

Regards,
Alex

[stiegi]

Hello Adder!

I tried the mame overclocking feature but it did not make things better. I think it has not got to do anything with performance of the pc but with how accurate mame can emulate the original hardware.

Somewhere there must be some mistake in calculation because most of the time games run smoothly but for certain special cases such as movement in diagonal direction (two directions combined) mame seems to have some problems. Otherwise I cannot explain it.

As far as legendary wings is concerned I made an interesting observation. When the character moves from left to right you get this microstutter but as soon as you press the jump button the scrolling will switch over to smooth scrolling as long as the character lands on the ground again. It seems like when the character jumps the scrolling speeds up a little and smooth scrolling takes control again. So my conclusion is (of course this is very theoretically) - there are two processes - the one the game itself controls scrolling automatically - but when you move the character you control the character and in this case it does not scroll smoothly anymore.

Another example is Scramble. In this game I get smooth scrolling all the time even when the ship moves diagonally. The difference to legendary wings is that the screen will always scroll automatically and is not controlled by the ship - so there are two instances again.

regards,

[Paradroid]

I haven't had a chance to check out the actual examples you've observed but I can confirm that some games just never scrolled smoothly and MAME's reproductions of these jerky movements are accurate.

Another classic example is Robocop. The horizontal scrolling just isn't smooth in MAME or running a PCB. It's just how it is.

The main thing is that you've confirmed that games known to scroll smoothly do so with your GroovyMAME setup.

[adder]

hey again, I agree with Paradroid and it is a difficult area unfortunately, as some games which do not have perfectly smooth scrolling/sprites, you would find is also the case with the arcade pcb.  some other examples are green beret (the scrolling is not particularly smooth), kung fu master (not perfectly smooth background scrolling), and perhaps ghosts n goblins also if I remember (not perfectly smooth background scrolling, instead it kind of 'jumps along'). with these games though, it may well be the case that they are also not perfectly smooth scrolling on the actual arcade pcb (maybe, maybe not). it's not really helpful looking at youtube videos of the actual arcade games in action as usually the quality and framerate of the youtube videos are simply not clear/accurate to have a close look.

there are some cases where overclocking does help some games: a good example is choplifter. try loading that game, start, then fly along the level to the left, look closely at the enemies on the floor (guns and jeeps etc) as well as the ground scrolling. it judders from time to time and doesn't stay smooth. however, if you overclock the maincpu in this game to 200% and retry the test, you will notice that the juddering has gone away and the game plays smooth. I think maybe this is an issue with mame perhaps (but who knows), .... anyway, whenever I play choplifter I overclock that game to 200% so it plays smoothly.

a really great fix on mametesters a while ago was making the game wonderboy run nice and smooth again. it had some problems with smoothness, but the mame dev called 'Hap' did a great job to fix the problem 

[Calamity]

I've confirmed that Commando does not scroll smoothly when moving diagonally. That must have been in the pcb too. It's an issue with animation itself that typically happens when the background does not move by a constant amount of pixels/lines per frame. If you move in the vertical direction, it scrolls 1 line per frame. But if you move on the diagonal, it scrolls 1 line only for even frames, then 1 horizontal pixel for uneven frames. That causes the yerky movement effect.

[adder]

off topic a bit but, a little tip if playing capcom's commando (I think I mentioned this before somewhere on the forum), the best set to play is the US set 1, because in the other versions, I noticed when you run up the screen of the first area/level, sometimes the gfx of the palm trees glitch/disappear (see pic below). the problem seems to be fixed in the US set 1 though. I thought it might be a mame bug so watched a youtube video of someone playing the arcade pcb, and the glitch occurred with his pcb also. 

[stiegi]

Hey guys!

thanks a lot for your postings this forum is really great - I also do believe that this issues happen in the original pcb perhaps the developers did not have so much time for the actual program or did not care so much about scrolling issues or it was developed for specific hardware. As far as mame itself is concerned it is really accurate.

As far as I remember ghouls and ghosts and ghostns goblins are two more games which seem to reflect the original hardware. Ghouls and ghosts has got some fine horizontal scrolling most of the time but ghosts and goblins has some jerky scrolling even though both have no special vertical refresh rate - I mean that there are other horizontal scrolling games which have the same vertical refresh rate and run fine - for example Shinobi and Rolling Thunder. So my conlusion is that it has got something to do with animation as Calamity said.

Another interesting game is Cadash - most of the time the scrolling is smoothly but from time to time I noticed some stutter as if the monitor had to catch up again with vertical refresh rate.

My understanding is that the programm of the game actually interferes with the calculation of the video signal even though it should be CONSTANT all the time???

regards,