Is SPC audio sample replacement possible?

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04-20-24 11:48 AM

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Main - ROM Hacking - Is SPC audio sample replacement possible?

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KAPIKYO

Posted on 09-03-17 08:26 PM

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Is it possible to replace instrument samples in games like Super Mario World and F-Zero? I imagine it'd be pretty difficult if so. I swear I have a vague recollection of visiting some obscure rom hacking board for Super Mario Kart music hacking where someone had mentioned it as an ostensible possibility, and had experimented with it in the past, but didn't have any kind of proof or preview. I'd like to start a dialogue about it and get people talking, maybe something can be figured out.

ps; I've tried googling for this sort of thing, but I'm really bad at wording google searches when it comes to rom hacks. Looking for the most basic of tutorials is a semantic nightmare. It's a wonder I've managed anything in my current rom hack at all.

blackhole89

Posted on 09-05-17 11:58 PM (rev. 5 of 09-06-17 12:02 AM)

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It's more often fairly straightforward than not. The DSP of the SPC-700 needs to know where the samples it is streaming are in memory, so it is easy enough to extract the sample data for a given instrument from a memory dump (SPC file). On the other hand, consistently changing the instrument is idiosyncratic to the game, as most game studios wrote their own engines (which, among others, tell the DSP what sample to use when, and sometimes even download them from the main processor on the fly) for the processor part of it. I made a pair of tools for extracting arbitrary samples and inserting them in SMW with DJ Bouche's SMAS engine patch a lifetime in internet dog years ago, which may still be serviceable.

(Unfortunately, unethical 2006!me did not include the source code with that release, and I have no idea where any extant copies of that would be.)

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Main - ROM Hacking - Is SPC audio sample replacement possible?

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