Rather irritating first time hack

Hey there everyone.

Just got started with the whole hacking scene thing and I thought I'd post something I've started with. It's not very good, and was just a play more than anything. I'm more interested in the sound kind of things more than anything and I'm quite interested in how the whole sound driver thing is implemented on here. All I've done so far is play with the tunings on what I guess is the lookup tables for the frequencies.

As a result, here's a version of Sonic but with music played by 5 year olds:

Clicky Click

See if you can last more that 20 seconds before reaching for the mute button :lol:

On a slightly more 'serious' note though, you'll notice that there's a horrible click sound twice at the end of the 'Sega' replacement sound. I'm trying to work out why, it sounds like a DC offset style click, but I deliberatly edited the sound so that it ends with the same DC offset, so I can't quite work it out.

Secondly I'm trying to look at the code that alters the speed of the music. Obviously the code for this can be found within the Speed Boots code I.e.:

Code (Text):

1. Obj2E_ChkShoes:
2.   cmpi.b   #3,d0; does monitor contain speed shoes?
3.   bne.s    Obj2E_ChkShield
4.   move.b   #1,($FFFFFE2E).w; speed up the  BG music
5.   move.w   #$4B0,($FFFFD034).w; time limit for the power-up
6.   move.w   #$C00,($FFFFF760).w; change Sonic's top speed
7.   move.w   #$18,($FFFFF762).w
8.   move.w   #$80,($FFFFF764).w
9.   move.w   #$E2,d0
10.   jmp  (PlaySound).l; Speed    up the music

The move.b #1,($FFFFFE2E).w line however doesn't seem to do anything except either 1 crash if the $ value is too low, 2 do nothing if its around a tolerance value or 3 corrupt the music if its too high.

However the line "move.w #$E2,d0" DOES seem to affect the music. If I change the value to E3 the music does not change speed (a la the address when the boots run out) and if I change it to anything lower it plays whatever value of sound effect that has that address.

So how does one actually go about altering the tempo of the tracks. And where exactly are the tracks stored in the de-compiled binary?

Cheers,
Pete...

 

Cheers Tweaker, thanks for both the warm welcome and the excellent advice (yeah I'm currently using the Hivebrain's split disassembly code)