Author Topic: FDS (Famicom Disk System) expansion audio issues  (Read 4669 times)

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Offline FDSFan

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FDS (Famicom Disk System) expansion audio issues
« on: July 20, 2016, 05:02 PM »
I noticed when comparing the expansion audio in Famicom Disk System games to real hardware the pitch is way way off and some effects seem completely busted.

See here: https://www.youtube.com/watch?v=npFeWVZHp8E

It's really bad in a direct comparison, and now that I've noticed it I can't not notice it.

Is there ever expected to be a fix for this?

I'd dive in myself and try to modify the FDS FPGA code but my HDL is really rusty and I'm not sure I could get very far.

Offline The_Atomik_Punk!

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Re: FDS (Famicom Disk System) expansion audio issues
« Reply #1 on: July 20, 2016, 05:46 PM »
Yeah, this is a known issue. Like you, I simply cannot play FDS games on the EDN8 because of the off-pitch FDS channels. Since Igor is obviously exceptionally busy with the EDGBA, perhaps he will eventually have time to take another look at this issue. I've previously proposed starting a funding campaign to make it worth Igor's time (via Patreon, or maybe just Paypal gifts), but no one really got on board.

There was someone on this forum who offered to look at the code, but I guess nothing materialized out of that. Anyone remember who that was? It seemed like he may have had a solution.

Offline hunterk

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Re: FDS (Famicom Disk System) expansion audio issues
« Reply #2 on: July 21, 2016, 04:15 PM »
In the short term, I think the best option is to pick up an FDSStick/FDSEmu and a RAM adapter.

Offline Arnold101

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Re: FDS (Famicom Disk System) expansion audio issues
« Reply #3 on: July 28, 2016, 04:28 AM »
edn8 need better os indeed.

Offline sneakernets

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Re: FDS (Famicom Disk System) expansion audio issues
« Reply #4 on: July 30, 2016, 01:05 AM »
Given that KevTris's HDMI mod also has quirks (near identical!) with FDS audio, it's likely that Krikkz and Kev both used the same spec sheets. Those sheets are obviously wrong somewhere.

And yes, there are pitch problems in Kid Icarus title screen sawtooth lead, and Murasame Castle sounds like total poo sometimes (lightning strike in title screen, castle music). I can put up with the Kid Icarus pitch problem, but Murasame Castle is unplayable. The sounds actually make me nauseated!  :'(

Offline MP2E

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Re: FDS (Famicom Disk System) expansion audio issues
« Reply #5 on: July 31, 2016, 12:16 AM »
This is correct! I've bugged kevtris about his implementation too(in a friendly way, of course), and he stated that documentation just isn't complete enough to get accurate simulation going in VHDL currently

Whether he's seen all the documentation out there or not, I don't know, but I'm inclined to believe he looked : P

Idk if there's enough interest but I would he willing to contribute funds towards a Famicom Disk System reverse engineering bounty, maybe the goal could be to write a community FDS mapper for Everdrive, I'm sure kev could then make use of that for the HDMI nes.

This implies that we could find someone willing to do it for the bounty, and could get enough to get a bounty going in the first place.. I'd love to help other than that, but I don't know if I can here

Offline Arnold101

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