Capcom CPS2 Hack Help (small change)

[GuilesBarber]

Hello,

I have been looking for a way to elimintate in game music of some CPS2 roms (Street Fighter Alpha and maybe Alpha 3). Does anyone know if there is a good resource for editing these files? I understand I just need to go in and change two values as I have an Alpha 2 rom that this mod was already implemented and the person who made it gave me a couple of hints on what to change.

I have done some searching and found that the structure for Alpha 1 is the same so I just need to get to the same locations and change the value. The address I was given doesn't really tell me which file in the zip to edit. Maybe it's one big file split into chunks? I can't really seem to find much info on the guts of a CPS2 arcade rom.

I figure I can use some form of hex editor to compare the two Alpha 2 files (edited and original) to see how they were changed and just locate the same file and location for Alpha 1 and change the values.

Maybe I am way off base or need to decrypt or it's more complicated than that?

Thanks in advance!

[FAST6191]

Arcade games tend to be extensively detailed in their respective part of the MAME source code (when most boards struggle to get more than 10 games you can afford to do such things).

Eliminating music is usually done in one of three different ways.

1) Setting volume to zero if such things are available for your format. If a song plays but speakers make no sound... then actually some might care if they want the sound gone to use the CPU for something else.
2) Fun with loops. If there is a loop command then slam it right to the front and make it so it just loops in silence.
3) Alter the size of the file as it were to be as minimal as possible.
3a) If there is a silent track or instrument set some might also repoint to have that play in place of the original audio.

The proper way would be to find whatever calls the audio format in the first place within the game's code and kick that in the head but that takes coding skills where the above not so much.

https://github.com/mamedev/mame/blob/master/src/mame/capcom/cps2.cpp#L19 somewhere in there probably detailing what aspect of the files deals with what.