How to alter settings to prefer speed over accuracy of laggy /slowarcade games?

catatung

Hello,

Recently I purchased a double dragon arcade cabinet. As I understand it, the CPU used was underpowered for this game and it can be seen immediately once there is a lot of things moving on the screen, that is to say, the lag is not created on purpose by the programming, it is because the cpu is overtaxed with too many instructions.

I've tried regamebox on a raspberry pi 3b+ and this plays very smooth - even at times when the original arcade hardware would get laggy. When I try it with the retropie image on the same raspberry pi 3b+, the lag is apparent (equal to that of the actual arcade hardware)

What I presume is happening here is that the retropie distribution is favoring accuracy of replicating the original hardware's capabilities and experience over efficiency, whereas default settings within regamebox distribution is tailored for efficiency instead.

I would like to determine how to configure/tailor the retropie distribution to perform for efficiency rather than accuracy in emulating the same experience as the original hardware provided, to the same experience as I get when I use the regamebox distribution.

Does anyone know if I am correct in my assumptions, and what settings differ which could be causing the lag in the retropie distribution? 10 seconds into the game it can be seen, once you move right and 2 or 3 bad guys come onscreen, the lag is immediately evident. This is on double dragon the original game.

Any ideas or help would be much appreciated. I prefer to use retropie but not at the expense of laggy gameplay when regamebox plays smooth all the way through.

catatung

catatung

Some comparisons I've done:

Regamebox retroarch version: 1.7.7
Retropie retroarch version: 1.8.5

Regamebox emulator process command:
retroarch -L /root/.config/retroarch/cores/mame2003_plus_libretro.so /home/x/rpi2jamma/roms/arcade/ddragon.zip

Retropie emulator process command:
/opt/retropie/emulators/retroarch/bin/retroarch -L /opt/retropie/libretrocores/lr-mame2003/mame2003_libretro.so --config /opt/retropie/configs/arcade/retroarch.cfg /home/pi/RetroPie/roms/arcade/ddragon.zip --appendconfig /dev/shm/retroarch.cfg

I've:

enabled FPS reporting and that is not falling
replaced mame2003_libretro.so with regamebox version of mame2003_libretro.so
removed mame2003_libretro.so entirely and confirmed emulator does not start, to make sure this was the correct location for this file
executed retroarch the same way regamebox does (retroarch -L /path/to/mame2003_libretro.so /path/to/ddragon.zip)

Nothing gets retropie to emulate the same way regamebox does. I can't figure out how regamebox is working around the emulated lag.

catatung

I have solved it!

It looks like it was the difference between using mame2003_libretro.so and mame2003_plus_libretro.so. I had copied mame2003_libretro.so from the regamebox distribution to the retropie distribution by mistake when I was testing to see if that file was the difference in performance... As can be seen above by my documentation of the command which runs the emulator in regamebox, it uses mame2003_plus_libretro.so.

So, to recap, if you are experiencing the usual slowdowns with double dragon while using retropie distribution and would like to eliminate it, you can just copy mame2003_plus_libretro.so from the regamebox distro into retropie wherever mame2003_libretro.so is... and of course have the settings set to use mame2003_libretro.so. Also, i assume if you install the mame2003_plus core and instruct retropie to use it, the effect would probably be the same.

Hope this helps someone out, I know there is lots of talk about laggy double dragon, and there really is no fix because it is emulating lag which was present in the actual hardware of the arcade cabinet... i've seen posts saying to use the bootleg version (ddragonb.zip) because it was built on better hardware, but this looks like a solid and more appropriate approach to fixing it!