Genesis Plus GX - PAL Video inaccuracies

Libretro Cores
#1

I’m using Genesis Plus GX as my weapon of choice for Megadrive emulation because for reasons I don’t understand it’s the only emulator that doesn’t remove the coloured borders.

PAL mode seems to work fine but when I hooked up my real megadrive to compare screen position (on my crt) I noticed the pitch of the audio in tue emulator was higher than the real thing. Basically I don’t think the audio is pitched down to match a real PAL console.

It seemed to run faster too because switching back and forth between the emulator and real console the emulator was running further and further ahead.

Am I missing an option or is this just something the emulator doesn’t cater for?

#2

How do i create my own question on this board? i see this is a new question… but nothing that says how to create a topic. only reply.

which is why this message, knowingly off topic, was created.

Thanks!

#4

Take this with a grain of salt, as I’m not a PAL user at all.

I know there are numerous sound options in the GPGX core options menu. There was a whole thread somewhere in the ‘cores’ section recently about setting the filters and settings to match Model 1 consoles, but I’m pretty sure that was NTSC. I’m guessing you’d have to just figure out the proper setting for the PAL variant.

That being said, it may also tie into the game speed. I’m sure you’re well aware of PAL’s slowdown on poorly converted games, which would also cause lower pitch sounds, but I think that the emulator speeds these games up to their ‘rightful’ speeds - so to speak.

I could be totally wrong, but that’s what I’d gather from what I’ve learned thus far about it all.

#5

PAL games should be outside of the “speed it up to 60 hz” window. However, turning on the frames-per-second counter should solve that mystery pretty quickly.

If they’re running too fast and their audio is too high-pitched, my guess is that they’re running at 60 hz instead of 50.

#6

I checked and retroarch is reporting 49.xxxx fps so definitely 50hz.

MAME by the way sounds the same as the pal console in pal mode with the same rom so it’s definitely not the rom being a europe only rom that is written for pal region either.

#7

Because the main crystal oscillator is different between NTSC and PAL models for colorburst generation, which in turn affects timing for other chips. 53.693175 MHz - NTSC (x15) 53.203425 MHz - PAL (x12)

It’s less than 1 percent, but that’s clearly enough to be audible

#8

Yeah I’m aware of that, in this case though it was down to me running the emulator on a crt and the refresh rate being matched to the existing modeline installed for that resolution, not the correct refresh of the original system, hence the slight difference in speed.