Quality/playability Of Emulation

[Burt]

As a homebrew enthusiast and owner of a 2.71 PSP, I was recently deciding between the purchase of either a 1.5 PSP or a GP2X, eventually going with the former.

Prior to this, I had read nothing but good things about emus developed for PSP. For example, they were said to emulate most 68K-based systems at full speed. In reality, it emulates Mega Drive and Neo Geo at close to that, but not at a constant 60 fps. Compromises are sometimes necessary to achieve this, e.g. frameskipping, tearing, and lower-quality/no sound.

I've seen similarly positive words for emus on the GP2X, and am wondering how close this praise is to reality. DrMD, for example, is commonly recognized as a full-speed Mega Drive emulator. Does this mean that it runs all games at 60 fps, vsync'd, no frames dropped, full-quality sound, etc? Or must compromises be made?

 

[yaustar]

The PSP I've seen similarly positive words for emus on the GP2X, and am wondering how close this praise is to reality. DrMD, for example, is commonly recognized as a full-speed Mega Drive emulator. Does this mean that it runs all games at 60 fps, vsync'd, no frames dropped, full-quality sound, etc? Or must compromises be made?

GP2X DrMdx @ 200mhz would be about the same as the PSP DGen emulator @ 333mhz. Don't quote me on that though.

Edit: In fact screw it, give me five and I find out.

Game: Sonic 3 (E)
CPU Speed: 260mhz
Framerate in game: 50-52fps
Sound quality: 22050
Frameskip: Auto (0-1, very smooth, I honestly couldn't tell)
VSync: Unknown
Had some issues with Water/Transperancies

Game: Sonic 3 (E)
CPU Speed: 200mhz
Framerate in game: 38fps
Sound quality: 22050
Frameskip: Auto (1-2)
VSync: Unknown
Had some issues with Water/Transperancies

I am interested why you are asking though since you already have a PSP. Having second thoughts?

Videos:
http://www.youtube.com/watch?v=Je9J589u3Yk&search=gp2x
http://www.youtube.com/watch?v=-_NrTS_ut74...amp;search=gp2x

 

[Godmil]

DrMD isn't a perfect emu *yet*, but I've had no problems with it. I've tried a ton of games and lemmings2 was the only one that I couldn't play (some transparency issues). It's 'almost' perfect, and I believe it's still being worked on (by a very skilled programmer) so it should be pretty much perfect soon.

 

[craigix]

Sonic3 is a pretty intense game to emulate i've noticed, it should be said other games reach 60fps at 200mhz.

 

[Epicenter]

Strange; I seem to get better performance than that. I haven't found any games that run at <59-60 FPS (NTSC Games mind you) at ~250 MHz ARM920T clock.

Strange; I seem to get better performance than that. I haven't found any games that run at <59-60 FPS (NTSC Games mind you) at ~250 MHz ARM920T clock.

If Reesy goes ahead with my advice and adds an M68000 clockrate control as he apparently intends to, you can crank down M68K clock to ~5 or 6 MHz for most games and achieve great performance, and probably full speed operation at 200 MHz. M68K emulation seems to still be the most stressful bit, though Reesy's also mentioned heavy optimization/rewriting of the tile-rendering code IIRC. It'll only get faster. In the meantime I'm yet to meet someone with a GP2X that can't reach speeds to run all MD games satisfactorily.

 

[DaveC]

As a homebrew enthusiast and owner of a 2.71 PSP, I was recently deciding between the purchase of either a 1.5 PSP or a GP2X, eventually going with the former.

Prior to this, I had read nothing but good things about emus developed for PSP. For example, they were said to emulate most 68K-based systems at full speed. In reality, it emulates Mega Drive and Neo Geo at close to that, but not at a constant 60 fps. Compromises are sometimes necessary to achieve this, e.g. frameskipping, tearing, and lower-quality/no sound.

I've seen similarly positive words for emus on the GP2X, and am wondering how close this praise is to reality. DrMD, for example, is commonly recognized as a full-speed Mega Drive emulator. Does this mean that it runs all games at 60 fps, vsync'd, no frames dropped, full-quality sound, etc? Or must compromises be made?

DRMd doesn't run all games at 60 fps. the FM timers aren't updated every frame either so some of the sound can be slightly off sometimes but not many notice as it is subtle. There are also no raster interrupt palette switches meaning no water line in Sonic for example. It will drop frames now and then too. So no the emulators on the GP2X are not "perfect". They are very good but not 100%

 

[rooster]

Sonic3 is a pretty intense game to emulate i've noticed, it should be said other games reach 60fps at 200mhz.

it should also be said that the Sonic 3 mentioned there was the european PAL region ROM so the 50-52 fps he got on his GP2X @ 260Mhz is full frame rate and the same as the real megadrive hardware.

 

[Epicenter]

There is no such thing as a perfect emulator .. even if it does run at 100% full speed. Emulation by its very nature is inaccurate. And the thing that's always the furthest off is sound.

 

[rooster]

There is no such thing as a perfect emulator .. even if it does run at 100% full speed. Emulation by its very nature is inaccurate. And the thing that's always the furthest off is sound.

I don't agree that emulation by its very nature is inaccurate. I believe that emulators are only inaccurate when they fail in the emulation task in some capacity.

If a specific piece of hardware has ALL the capability of another piece of inferior hardware then a 100% emulation is definitely possible.

Your comment about sound: I can see that a 44.1Khz+ emulation of an analog sound chip could never be truly accurate because by nature an analogue synth chip does not output a sample, but an emulator would, so because a high resolution sample is only a representation of the original wave it is an approximation rather than a true 100% emulation. However, if the original sound hardware was a DAC sample-playing technology, perfect emulation can be achieved on a machine capable of playing samples at the same sample rate or faster.

As for CPUs: If a software emulated processor moves bytes around in memory just like its hardware counterpart and takes the exact same number of emulated clock ticks to achieve this, and if it executes interrupts at the exact same timeframe as its hardware counterpart - how is this in any way inaccurate by nature? I don't think it is.

I believe the only reason some emulated CPUs used in some GP2X emulators are considerred inaccurate is because they are known not to duplicate the entire hardware functionality of the chip in question. This is down to bugs or known ommissions in the feature set - nothing to do with the very nature of emulation.

If what you claim was true, there would be no software CPUs that perfectly emulated their hardware counterparts on any platform - but obviously there are.

 

[yalborap]

There is no such thing as a perfect emulator .. even if it does run at 100% full speed. Emulation by its very nature is inaccurate. And the thing that's always the furthest off is sound.

I don't agree that emulation by its very nature is inaccurate. I believe that emulators are only inaccurate when they fail in the emulation task in some capacity.

If a specific piece of hardware has ALL the capability of another piece of inferior hardware then a 100% emulation is definitely possible.

Your comment about sound: I can see that a 44.1Khz+ emulation of an analog sound chip could never be truly accurate because by nature an analogue synth chip does not output a sample, but an emulator would, so because a high resolution sample is only a representation of the original wave it is an approximation rather than a true 100% emulation. However, if the original sound hardware was a DAC sample-playing technology, perfect emulation can be achieved on a machine capable of playing samples at the same sample rate or faster.

As for CPUs: If a software emulated processor moves bytes around in memory just like its hardware counterpart and takes the exact same number of emulated clock ticks to achieve this, and if it executes interrupts at the exact same timeframe as its hardware counterpart - how is this in any way inaccurate by nature? I don't think it is.

I believe the only reason some emulated CPUs used in some GP2X emulators are considerred inaccurate is because they are known not to duplicate the entire hardware functionality of the chip in question. This is down to bugs or known ommissions in the feature set - nothing to do with the very nature of emulation.

If what you claim was true, there would be no software CPUs that perfectly emulated their hardware counterparts on any platform - but obviously there are.

I would say that emulation can't be completely accurate when it comes to the entire EXPERIENCE. Let me give you an example.

We start with a PC, an NES emu, and a Super Mario Brothers 3 rom. Boot her up, play with the keyboard. The actual emulation is perfect. Every bit of sound is exact, every pixel perfectly placed, it's exactly as it should be.

But, you didn't play NES games with the keyboard. You need a gamepad. So, you go buy a common USB gamepad.

Still, it doesn't feel quite right. You go online and get one of those cool USB gamepads that are built out of NES controllers. The controller feels perfect, the game looks right, it's wonderful!

But...You didn't play your NES sitting in an office chair in front of a moniter, you played it on the couch in front of your TV.

So, relocate. We play it on an HTPC, sitting on the couch. It's wonderful, the game's playing, the controller works right...

But, still, there's that underlying OS, and the way you select the rom, and it just doesn't feel right.

Okay, easily fixed. We set up a front-end it boots into.

Still, it's not right, and the HTPC doesn't look anything like an NES.

So we switch to an NES PC. We even take an NES' controller plug and port, and wire it up so they work as USB ports and you can plug the NES controller in just like the old days.

Still, you don't put anything in...

Okay. We start taking the disc of roms out, have the disc drive open out of the cart door, and it's just GREAT.

But you don't put discs into an NES, you put carts.



You get what I'm saying? By the time you have something that's perfect, you're just holding an NES and some carts.

Of course, I might have COMPLETELY missed the point.

 

[Azure]

Screw it, I'm going to make videos for a lot of the GP2X's emulators today. I'll upload them by tonight.

 

[Orkie]

But...You didn't play your NES sitting in an office chair in front of a moniter, you played it on the couch in front of your TV.

Well, I've always played sat in an office chair, because my TV is right next to my monitor I think that once you have the right controls, it is no different to playing on the proper thing (in fact, I often use a PlayStation emulator instead of the PlayStation because it is more convenient to just pop the disc into my PC than getting up to set up the console).

 

[moz]

Screw it, I'm going to make videos for a lot of the GP2X's emulators today. I'll upload them by tonight.

sounds most excellent

 

[Azure]

Screw it, I'm going to make videos for a lot of the GP2X's emulators today. I'll upload them by tonight.

sounds most excellent

Haha, I forgot about this (Yesterday was my cousin's birthday). I'll definetly get them up today. I'll put the video on Google Video, too.

 

[DavidBeoulve]

Screw it, I'm going to make videos for a lot of the GP2X's emulators today. I'll upload them by tonight.

sounds most excellent

Haha, I forgot about this (Yesterday was my cousin's birthday). I'll definetly get them up today. I'll put the video on Google Video, too.

Aw man, it takes them days to "censor" your videos and stamp them "approved."

I posted my 8 videos to them and then YouTube and found the latter much easier, even though I dislike its weighing system. Also, YouTube as able to keep the series together, whereas when you find them in Google Video, it gives the unregistered user no way to figure out where the others in the series are.

Just fair warning.

Edit: Added linkage

 

[yalborap]

But...You didn't play your NES sitting in an office chair in front of a moniter, you played it on the couch in front of your TV.

Well, I've always played sat in an office chair, because my TV is right next to my monitor I think that once you have the right controls, it is no different to playing on the proper thing (in fact, I often use a PlayStation emulator instead of the PlayStation because it is more convenient to just pop the disc into my PC than getting up to set up the console).

I honestly do the same time, except I usually rip them to the laptop's hard drive. Combined with several gamepads, a nice batch of other emulators, and a card reader in the thing(plus a wireless connection to the PDA), I'm pretty much set for any gaming I could possibly want to do that came before the PS2, as well as general media. DVD drive too, so I can watch or rip movies I buy on the go.

But still, you get the idea. Now, if you actually care about the 'original experience' enough to go beyond a good gamepad and maybe a tv-out setup is a completely different story, and one that's different for every person.

 

[DavidBeoulve]

Pardon my ignorance, but is PSX emulation that good on the PC now?

I have all my old PSX games but I don't play them much. Saving in the middle of ANYWHERE would certainly get my interest up.

 

[yalborap]

Pardon my ignorance, but is PSX emulation that good on the PC now?

I have all my old PSX games but I don't play them much. Saving in the middle of ANYWHERE would certainly get my interest up.

Very good. Very, very good. My laptop is 1.5 Ghz, 512 megs of ram, and a bad video card. I usually ran a MASSIVE number of apps back when I used it as my main machine. I could play just about any PS game fullspeed.

It's gotten just plain amazing on even relatively low-end machines. Seeing the kind of performance that could be worked out of that machine and others far weaker than it gives me huge hope for the GP2X PSX emulator's future performance.

Plus, you can rip the games to the hard drive with a standard disc ripping app, or you can play them from the actual drive. It's quite nice.

 

[Azure]

Sorry, I can't do the video. I'm selling my GP2X

 

[Epicenter]

That's uh, really random.

At any rate, my argument that emulation is never fully accurate it because a lot of the information used to code them is reverse-engineering not based on real published hardware specs, for proprietary combo-chips for which there is no documentation. Example, the NES' RP2A03 IC contains the MOS 6502 CPU and a custom proprietary sound processor that is just now reaching the point where it's almost identical to the real thing .. about 22 years after the NES' release. The MD's YM2612 is tricky to emulate due to the complexity of the chip in all likelihood, while many others are just analog in nature, like the SiD.