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Retroarch framerate shows 60fps during slowdowns

Posted: Sun Mar 01, 2015 12:32 am
by cacophony555
I've been trying to compare various SNES emulators on the Raspberry Pi 2 and really like the snes9x-next core for RetroArch, mainly because the audio sounds so much better. But the one thing that bothers me is more prominent slowdowns in specific areas of certain games. For example, near the very beginning of Super Ghouls and Ghosts when the enter the two caves with the fire creatures. I haven't noticed as much of a slowdown with other emulator options.

So I enabled the framerate dispaly via the retroarch menu and even when considerable slowdowns occur it's still showing a rock solid 60fps. Can somebody explain this?

Re: Retroarch framerate shows 60fps during slowdowns

Posted: Sun Mar 01, 2015 12:38 am
by toxibunny
You have frameskip set to 0, and that means when the emulator can't keep up, it gets slower rather than jerkier?

Re: Retroarch framerate shows 60fps during slowdowns

Posted: Sun Mar 01, 2015 2:15 am
by Toad King
The framerate debug text in RetroArch only updates every couple of seconds (technically every 256 frames) and gives an average framerate since the previous update. It is not instantaneous.

Re: Retroarch framerate shows 60fps during slowdowns

Posted: Sun Mar 01, 2015 12:13 pm
by Vanfanel
cacophony555 wrote: So I enabled the framerate dispaly via the retroarch menu and even when considerable slowdowns occur it's still showing a rock solid 60fps. Can somebody explain this?
You must differenciate "internal" framerate from the "external" one.
The slowdowns you mention in Super Ghouls'n'Ghosts are internal slowdowns: this means the game slows down on the emulated system, but emulation is still run at ~60Hz, hence it's perfectly correct that RA shows 60FPS, as it DOES cope with every FPS of the emulated system.
Any "emulated system" slowdown is "internal": RA doesn't have to reflect this in the framerates it displays.
Load a more CPU-intensive core, like MAME with newer games, and you will see how the emulator host can NOT cope with every emulated frame per second, and you will see FPS drop down.

Re: Retroarch framerate shows 60fps during slowdowns

Posted: Sun Mar 01, 2015 6:02 pm
by cacophony555
Vanfanel wrote:
cacophony555 wrote: So I enabled the framerate dispaly via the retroarch menu and even when considerable slowdowns occur it's still showing a rock solid 60fps. Can somebody explain this?
You must differenciate "internal" framerate from the "external" one.
The slowdowns you mention in Super Ghouls'n'Ghosts are internal slowdowns: this means the game slows down on the emulated system, but emulation is still run at ~60Hz, hence it's perfectly correct that RA shows 60FPS, as it DOES cope with every FPS of the emulated system.
Any "emulated system" slowdown is "internal": RA doesn't have to reflect this in the framerates it displays.
Load a more CPU-intensive core, like MAME with newer games, and you will see how the emulator host can NOT cope with every emulated frame per second, and you will see FPS drop down.
So the slowdowns are actually a more accurate representation of the original hardware? I was hoping that would be the case but was originally suspect of that theory because original hardware gameplay videos online don't seem as bad but there's always some variability so it's hard to tell for certain.

While I have your attention, can you clarify why you think genesisplus-gx is a poor choice for the megadrive ? I heard elsewhere that it was far more accurate with megadrive sound emulation than picodrive.

Re: Retroarch framerate shows 60fps during slowdowns

Posted: Mon Mar 02, 2015 10:39 am
by Vanfanel
@cacophony555, believe me, if see slowdowns in a game but RetroArch says 60FPs, then it's slowing down just like in the original system.
As for youtube gameplays, these are NOT accurate to compare framerates for a number of reasons...

The genesis-gx libretro core is great! On the other hand, sing genesis-gx as a standalone emulator is a bad idea (I don't know if there's a standalone version really, nor do I care).
The problem used to be that the genesis-gx libretro core was not fullspeed with Genesis games in the original Pi. Now that we have the Pi2, it's the best Master System / Genesis emulator by far: I have it running on non-pi ARM linux boards and it's perfect.

Re: Retroarch framerate shows 60fps during slowdowns

Posted: Mon Mar 02, 2015 5:08 pm
by cacophony555
Thanks Vanfanel!

If you have a moment it would be great to see your list of recommended emulators for each system now that the Pi 2 is out.

Re: Retroarch framerate shows 60fps during slowdowns

Posted: Mon Mar 02, 2015 5:27 pm
by KitchUK
I would also be interested to see your opinion on the preferred cores for the RPi 2.