Developer of the PS5 emulator sharpemu comments on PS4 compatibility

#emulation #ps5 #ps4

The messages from the thread, copy-pasted as a continuous text:

This thread explains why we're working on backward compatibility when projects like shadPS4 and the so-called decompilation projects already exist.

First, the decompilation projects are a basically doesn't exist. They're simply shadPS4 packaged as bloodborne.exe, bundled with FSR/DLSS DLLs and Bloodborne's 60 FPS patches. I'm not belittling anyone's work, but installation convenience aside, these are not ports.

Second, if a PS5 can run PS4 games, why shouldn't a PS5 emulator be able to do the same? If our goal is to emulate the console, backward compatibility is part of that goal.

So why did we initially say we wouldn't do it? Because projects can evolve along the way. That doesn't mean we're trying to compete with shadPS4. Absolutely not. shadPS4 is an incredible project that I personally have enormous respect for.

But the PS4 has games that are extremely valuable to me, like Bloodborne. And this is a challenge, too.

On the technical side, as I've said before, we're not actually emulating two consoles. We're taking inspiration from the PS5's backward compatibility. Just as the PS5 doesn't emulate a PS4, our emulator doesn't emulate a PS4 either.

We run a translation layer using our existing PS5 shader recompiler, with almost zero performance impact, just like on the PS5.

Also, while working on this, we had conversations with shadPS4's lead developers. Their opinions mattered to us, and we practically asked for their permission. If they'd objected, we wouldn't have released this project.

And of course, there were things we benefited from in shadPS4. For those contributions, we've added all of their GitHub usernames to the relevant commits in our repository.

We haven't matched shadPS4's performance yet. That's because our PS4 backward compatibility uses the same execution and rendering pipeline as our PS5 emulation, meaning the existing performance overhead on the PS5 side carries over to PS4 games.

To be clear, we're not developing two separate emulators in parallel. GnmMode builds on the infrastructure we already have. We share the same core components rather than maintaining two independent implementations.

Of course, there are still PS4 games that need additional work before they can boot or run correctly. But since the fundamental infrastructure is already in place, supporting them doesn't require building an entirely new emulation system from scratch.

That doesn't mean we're shifting our priorities. Improving performance and addressing the existing overhead remain more important than expanding PS4 game compatibility right now. Backward compatibility is an extension of SharpEmu, not a second project.

More technical info;
https://github.com/sharpemu/sharpemu/blob/main/docs/gnm-mode.md