Desert War PCB (ymf271) Footage

kirishima · Post by **kirishima** » 2017-10-07, 6:23:09

I'm bored, so here's a trash post with (hopefully) pcb video of Desert War I found on Nico Nico Douga. This is in case there's someone out there who wonders what the ymf271 should probably sound like.

http://www.mmcafe.com/nico.html#http:// ... /sm7553608

http://www.mmcafe.com/nico.html#http:// ... /sm7553855

http://www.mmcafe.com/nico.html#http:// ... /sm7554095

These videos seem important enough to me because many pcm samples don't sound cutoff like current emulation, and there doesn't appear to be any reverb. Is the ymf271 even capable of reverb, or was that something the Bloody Roar sound composers added to the streams for the console versions like what Sega did for Virtua Fighter's arcade ost...?

Edit: I thought the videos would at least appear here, oh well.

Stefan_L · Post by **Stefan_L** » 2017-12-16, 22:40:16

I have done recording from the Desert War arcade pcb... so this is as perfect sound you can get

http://arcade.ym2149.com/osv/desert_war_arcade_osv.zip

Attention! I call it OSV but that is not 100% true since the Jaleco Megasystem2 does not output stereo sound and my recordings do and thats because i have modified the PCB to output s/pdif directly after the YMF271 soundchip (before the DAC).

ctr · Post by **ctr** » 2017-12-16, 23:17:40

Thanks for the direct recording, indeed it's the best you can get for now. Unfortunately, since the OPX chip is kind of obscure, good emulation may take a while if it will ever happen. I think testing on the real chip would be needed in order to develop a good emulator for this chip.

kirishima · Post by **kirishima** » 2017-12-17, 1:39:29

But any idea why the samples are so cut off in the emulation of most of these games? They all play, they just fade out quickly. Although the recent fix to get more sfx working in this game broke some of the music in both Bloody Roar games.

GTheGuardian · Post by **GTheGuardian** » 2017-12-17, 7:18:52

That's because the envelope timings are wrong. Specifically the Release Rate is way too fast compared to PCB/OST Recordings. I already made a bit of a proof of concept by slightly decreasing the release rate which makes it slightly better albeit still little bit inaccurate. (And not only that but there are still other issues like the inaccurate FM emulation among others)

Edit: In case anybody's curious I only changed the following line in ymf271.c:

Code: Select all

rate = get_keyscaled_rate(slot->relrate * 4, keycode, slot->keyscale);

I changed relrate * 4 to relrate * 2 but as I said, it's only a hackish workaround and not fully accurate

kirishima · Post by **kirishima** » 2017-12-21, 8:33:43

@GTheGuardian

1.75 might be more accurate from some more testing I've done. Changing that line doesn't appear to break anything that wasn't already not working from some testing across several different games, but testing wasn't really thorough.