What would it take to get a dynarec into beetle-saturn?

General Development
#21

I finally had some time to look into this a bit more. I wasn’t able to build YabaSanshiro to debug it, however I did succeed in compiling Yabause 0.9.15. This revealed that the dynarec crashes at the same point when starting a new game in Burning Rangers, similar to YabaSanshiro.

The cause of the crash is a bug in the register allocator, which fails to allocate enough registers for a certain instruction. This is easy to fix, and Burning Rangers seems to work fine with the fix applied, but I’m surprised that this apparently obvious bug went unreported and unfixed for years.

I think having working Saturn emulation on handheld devices would be great, but clearly this is going to take a lot more work to test and debug. Does anyone really care about Saturn emulation, or is this just not worth the effort?

Ymir looks interesting, but I couldn’t get it to build from source as it seems to have dependencies on some very recent stuff. Ymir clearly isn’t going to work on something from Anbernic or Trimui, and probably not on Android either.

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#22

I did when i wrote those yabasanshiro and kronos libretro ports years ago, but it was honestly a bit of a disappointment after i noticed multitap support was kinda broken. My main motivation was to create a mini-pc replacement for my dead saturn (which has bomberman, 2 multitaps, and a load of gamepads).

I think saturn still has a huge fanbase.

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#23

Lots of people love the Saturn, they just have accepted “Saturn is too hard to emulate”. It makes sense to have a good Saturn emulator, these beasts are getting older/prone to failure, expensive and games prices have skyrocketed.

#24

Currently, I use Beetle Saturn and Mednafen on Windows and the Poco Pad (Android).

Both can run most games full speed, but I can’t ignore the input lag on either. On Swanstation, for instance, it has so many enhancements, fixes and the ability to use runahead (core options), to reduce even further an already acceptable latency.

With Saturn, the story is different, it always remembers me I’m playing these games with added latency, and I feel that in each input.

With that, all I’m saying is that probably many like me want a fast and accurate Saturn emulator, with improvements many other cores/emulators have.

But for now, we have to accept the current state, while wishing for things to get better with time. And yes, I play lots of Saturn games and it was the console which, besides gaming, inspired me to start drawing, learning English, Japanese, and getting into new genres I never had before it, such as FPS, RPGs, Strategy, Adventure and much more.

If, at some point, dynamic recompilation gets implemented, it will probably be a milestone, but I also know SSF for a long time and while it’s quite fast for a Saturn emulator, running on anything dual core, it still suffers from input lag. So, this is something we still need to see to believe, I mean, if dynarec will and possibly will, not only make this core run on more modest machines, with reduced latency.

Btw, Saturn.emu, which is based on Mednafen Saturn for Android, run chd games and I’m quite impressed that this mid range tablet can actually run 99% of the games I throw into it full speed.

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#25

For the reminder, original hardware had massive input lag, guardian force was infamous with its ~10 frames of input lag, and cotton was barely better. Emulation seemed to leverage them to 3 for some reason (probably inaccurate smpc emulation) the last time i tested.

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#26

This is something I’d love to test myself, since I don’t have original hardware to compare, I wonder if someone had done that so far. I know Capcom games have added latency on purpose, such as Street Fighter Alpha and many more, I mean, on arcades and their ports.

Now, from memory, I’m not able to remember exactly how these games felt.

Still, it makes us wish for a faster Saturn emulator that will possibly benefit from reduced input latency options. Rayman run almost full speed with runahead at 2 in my PC, but it will stutter from time to time, even though the game responsiveness is greatly improved.

If I play Street Fighter Alpha 3 on Swanstation and set run ahead to 2 or 3, I’m pretty sure it plays better than on original hardware, because these games had that extra “weight” on pupose. The PSP port is even worse (real hardware), like Metal Slug 7 compared to Metal Slug XX port on the PSP, the NDS feels so much better to play, specially on MelonDS, as Desmume is abysmal in comparison.

#27

It turns out i mistook guardian force saturn with its stv counterpart, the saturn version had a normal input lag of 3 frames.

I know tests exist because i saw them years ago, and i’m pretty sure 3 frames was considered low on original hardware. Sadly, questions about emulators and remakes are flooding search engine results nowaday so i couldn’t find that source anymore.

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#28

I talked about this on kronos’s discord and it seems 2 frames is the theoretical limit hardware-wise if you properly optimize your game for saturn’s smpc. I only got vague answers when i asked about games actually achieving those 2 frames though :sweat_smile:. Also, it seems only achievable on 2D games, 3D games need an additional frame.

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#29

What about PS/N64 games, say a 60FPS 3D game such as Tekken 3 and maybe F-Zero 64? Have anyone tested them? Maybe Virtua Fighter and other 3D fighters on the Saturn would be good to measure input lag?

Some time ago I overclocked Quake II on the PS1, via Swanstation, the game has unlocked frame rates so we can reach 60 FPS and it’s transformative compared to how it plays originally, one thing that is very noticeable is the input lag that is vastly improved. I may have a footage of that still.

With that, I believe that when PCs get better and they are already so fast today, we’ll be able to even surpass these Saturn/N64 input lag issues, like we can with the PS1.

Edit: Here it is:

https://youtu.be/pSCllF_9EqA

BTW, when I mentioned improving input lag with Quake II on PS1, it’s the lag inherent from the game’s own performance and not run ahead or preemptive frames and the such, this is mostly due to the console 3D capabilities with specific game engines.