NEOCD/SDL DC V7

BaldMonk · Post by **BaldMonk** » Thu May 20, 2004 4:03 am

Yeah, I really notice all the small touches the programmers have put in these games... they're so complex.. no wonder the roms are so large. Yes, the graphic errors are very wierd, and the shadows and stuff I think depend on what frame you start the game on... for example, somtimes the character on the left has no shadow, and sometimes the one on the right has none.

Now, I'm off to play Savage Reign...

Ian Micheal · Post by **Ian Micheal** » Thu May 20, 2004 4:08 am

Im becoming a big neogeo fan my self. never was to much but the CD system Is to me a lot of fun. Im looking into geting a real one .. no money but checking cost of one.

This system should of been more Prasied games are great are Much better then other systems.

BaldMonk · Post by **BaldMonk** » Thu May 20, 2004 4:30 am

Real ones are PRETTY dare. A friend of mine picked up a few cart ones a while ago... I didnt even know they were released here. I'll ask him for a price... mind you, he lives in the UK now, so shipping would be arse.

Ian Micheal · Post by **Ian Micheal** » Thu May 20, 2004 4:57 am

looks like only way is this project for me to play them. just dont like emulation on a pc does feel as good.

Means i have to get this perfect even more no choice!

BTW I get NO CDDA on rally chase on the pc/dc version of the emulator only sfx on the pc build.

So the CDDA error is not just on the dc version.

Post by **Quzar** » Thu May 20, 2004 5:01 am

Ian Micheal wrote:
BlackAura wrote:
Ian Micheal wrote:Frameskip is pesudo auto. pleanty of better games to play. and with no error stick to those.
Are you sure it's not real auto frameskip. If it's the same code that you've got in that copy of the Genesis Plus source code, it is auto frameskip. The one I use in Genesis Plus is slightly different (it uses milliseconds instead of seconds, and is implemented completely differently) but it should do the exact same thing. The only difference is that mine doesn't skip more than 10 frames, and yours doesn't skip more than 4 or 5.
One i gave you is slighty changed. Quzar beleives his code is not i beleived it was. So there's a it's auto it's not frameskip war.

So pesudo was the midle ground. with the heavy underclock setting frameskip makes not that much change any way but helps to take away a few cycles leting every thing run pesudo fullspeed.

We have no SFX yet i think enjoying it for a while was needed V7 lets the user enjoy it now. While i try to find real speed.

Trust me, the code i put in NeoCD is not automatic frameskipping unless i do not understand the term. There is no real time changed value in the calculation of whether a frame should be skipped or not. if over 4*(500/33) time has elapsed since the last frame was rendered, then the next one is skipped. All my attempts at having that value be based on the amount of time since the last frame did not work (i think i was submitting them to be in versions 3/4).

Ian Micheal · Post by **Ian Micheal** » Thu May 20, 2004 5:04 am

Well Most people think it is quzar. it adjusts Close enff for me.

BaldMonk · Post by **BaldMonk** » Thu May 20, 2004 5:34 am

Arggg, now it's just getting confusing for me... this is why I'm not a coder... lol. so, if its on 4, does that mean on 5 there wouldn't be much notice of jerkiness?

Ian Micheal · Post by **Ian Micheal** » Thu May 20, 2004 8:26 am

I dont think it's thats. Every version below is slower. I have made sure every version Is a step up in ether function or speed. Thats the way i work or i dont release any thing.

Nothing much you can do when the dos version has the same faults is there.

BaldMonk · Post by **BaldMonk** » Thu May 20, 2004 9:44 am

Haha, yeah, your a workaholic alright Ian my friend. It wouldn't be what it is without your and the teams dedication.

One thing though, if its not too much hassle, could you just try locking the frameskip to an odd number and see if it solves the flashing problem? lol... I just wanna know through fact rather than assumption.

But your the coder, so your assumption is most probably right...

Ian Micheal · Post by **Ian Micheal** » Thu May 20, 2004 10:32 am

Did not seem to do any thing when i tryed it. i feel ill.

Fosters · Post by **Fosters** » Thu May 20, 2004 11:45 am

I dont know if the quzar bits are on or not, but you ARE forcibly skipping every other frame still, which is why things that flicker may not be displayed.

In fact im not sure the timings on quzars bit were adjusted to take into account the running two frames each time, Id be very suspicious at least that this isnt working as intended.

Underclocking may help on some games, but will make games which struggle to reach full speed on the NeoCD (ie the metal slug games) worse as insufficient processing will be done each frame, it could even break them.

Fosters

Ian Micheal · Post by **Ian Micheal** » Thu May 20, 2004 12:01 pm

CPU does not run at fullspeed Leaving it at the correct speed does not fix the slowdown but it makes it worst. underclocking lets every thing speed up and not waste the cycles trying to emulate the cpu at 12.5 mhz which it can not do at all and render video.

Maybreak games but the smooth-ness and speed is well worth that chance.

PS i can send you a build with this removed it suffers badly from slow down and is half the speed of the curret release.

Fosters · Post by **Fosters** » Thu May 20, 2004 12:33 pm

most Neogeo games draw a frame and sit for a while idleing the cpu until the vblank irq arrives. underclocking means you burn less idle cycles between finishing processing frame and vblank. As you point out saving on these wasted cycles is a great way to gain extra speed in an emulator.

It just worries me on metal slug 1/2 that if they havent finished processing by the time vblank arrives when running for the correct amount of cycles, that when you run it for less, some vitally important piece of code doesnt get run and hence _possibly_ breaks something.

what would be really cool would be a way to detect when a game has done all its going to do for that frame and interrupt the cpu then.

Its a shame there isnt a SH4 68000 emulator, as there are many systems that could benefit from one.

Fosters

Ian Micheal · Post by **Ian Micheal** » Thu May 20, 2004 12:39 pm

Yes Agreed. Both games have been near completed. I think the underclocking brings the Gun Turrent bug. Well im here for the long run i will get this fullspeed proper fullspeed even if it killsme.

The Dos version runs fullspeed on a 200mhz cpu p1 and with sfx and cdda. I Tested it tonight.

Main changed are both cpus are X86 asm cpu cores. And video is allegro which is slower then SDL on tests ive done on the same pc.

Speed loss is due to going back to c based cores. We need to get the main cpu using less cycles or fullspeed is not going to happen.

Ian Micheal · Post by **Ian Micheal** » Thu May 20, 2004 1:32 pm

Well Flashing shadow problem was due to underclocking not frameskip. Seeing what i can do.

Post by **Quzar** » Thu May 20, 2004 4:05 pm

Yea, even switching the frameskip to odd would do nothing if the underclocking was cutting every other frame. I think if you set one to 175000 then it would probably work the same as with 2 timeslices but without the flicker

BaldMonk · Post by **BaldMonk** » Thu May 20, 2004 8:07 pm

Ahhh... I didn't really realise what underclocking did... so, in effect it's similar to frameskip?

Post by **Quzar** » Thu May 20, 2004 8:55 pm

kindah

basically you are telling the emulated CPU to run at a speed lower than its true speed. The doubling i am talking about is that the 'pseudo frameskip' of ians actually just tells the CPU to refresh 2 times each time he has the video render. So basically it shows half of all frames before frameskipping takes effect. It performs almost identically (to my eyes =\) without that though.

BaldMonk · Post by **BaldMonk** » Thu May 20, 2004 9:31 pm

Hmmm, maybe next release have 2 versions. One with, one without and let us judge to either keep it in or not?

Post by **Quzar** » Thu May 20, 2004 9:34 pm

I could give you people one without in 15 seconds, but i wouldnt do that to ian, since it is his port.