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Romhacking => ROM Hacking Discussion => Topic started by: Magil on April 10, 2011, 11:06:37 pm

Title: PSX sound problem
Post by: Magil on April 10, 2011, 11:06:37 pm
The game is Culdcept, psx version.
After I moved the card packages to other places, something odd happened to the sound effects. That is, before a card battle, the names of the two cards will be read. But after the edit, the voice is gone, instead, a random beep or trumpet is played. :o

Thing is, I don't know how to debug sound related stuff. Any ideas on how to find the problem?
Title: Re: PSX sound problem
Post by: Gemini on April 11, 2011, 06:07:35 am
You're overwriting sound samples with other data before an SPU transfer is about to happen. Solution? Move your stuff somewhere else.
Title: Re: PSX sound problem
Post by: Magil on April 11, 2011, 09:17:25 pm
So I need to watch SPU upload? Will check that, thanks.
Title: Re: PSX sound problem
Post by: Gemini on April 12, 2011, 06:02:32 am
I forgot the other possibility: you're overwriting other sound data that isn't uploaded to the SPU. Basically, if the game is using VAB or whatever other format, it has to keep somewhere in RAM the information useful for playback (offset, loop point, frequency, pitch, etc...) which is managed by the CPU through memory registers. When that information is corrupted you can expect the SPU to simply work randomly and creating all sorts of nasty playback effects thanks to the CPU sending it junk commands.