Music fade out

[thegeps]

I need to fade a song before stop it. Time ago you wrote me this:

“As for the fade out itself, simply decrease the volume from 0 to 16 (move from one value to another after a few frames, it will sound smoother), with a threshold detection:

ld a,(PLY_AKG_PSGReg8) ;Then 9 and 10.

sub 1

jr nc, NoDeb

xor a

NoDeb ld (PLY_AKG_PSGReg8),a

Do that before the call to PLY_AKG_SendPSGRegisters is done, it will be simpler (warning, this method needs A, so save it first if you modify it).”

well, I found

PLY_AKG_PSGREG8

and

PLY_AKG_PSGREG10

but no reg9 variable?

and by “Do that before the call to PLY_AKG_SendPSGRegisters is done” you mean that I have to put some code inside your player? O_o (like putting there a variable check and call the regs decrease before that calling?)

[Targhan]

Yes, you have to modify the player. I may add this as a build-in feature in a next version (with a conditional flag, most people don’t want to use this).

I guess you’re using the ROM player? Check the PLY_AKG_PSGReg9_10_Instr label… But even in this case the PLY_AKG_PSGReg9 is present, from what I read.

[thegeps]

Yep, I’m using the ROM player. There isn’t the reg9 label…
The 9_10instr is there, and I saw that is used to stop the song by resetting bot H and L and then doing

Ld (ply_akg_psgreg9_10instr),hl

So, how can I use that? L byte is for reg9 and H byte for reg10?

[thegeps]

ok, I’m actually doing this, and it works.
Not the best or most elegant solution but I’m fine with it.

First of all I’ve set two variables

mfade: equ 0e7f1h
volume equ 0e7f2h

mfade is a flag: 1-do a fade, 0-play as usual

in the ROM player I’ve done this mod, just after the ply_akg_sendpsgregisters label

;original code
PLY_AKG_SENDPSGREGISTERS
push af
ld a,(mfade)
or a
call nz,fade_music
pop af
;original code

in my source I have the routine to be called:

fade_music:
ld a,(volume)
ld (PLY_AKG_PSGREG8),a
ld (PLY_AKG_PSGREG9_10_INSTR),a
ld (PLY_AKG_PSGREG9_10_INSTR+1),a
ret

and this piece of code where I need to have the fade out:

ld a,11 ;this set start volume value
ld (volume),a
ld a,1 ;set the fade flag
ld (mfade),a
volume_fading:
ld b,25
call wait ;wait is a routine synched with vblank that wait b vlaue * 1/50th. so, before decreasing the volume by 1, half sec will pass
ld a,(volume)
dec a
ld (volume),a
jp nz,volume_fading
ld b,25
call wait ; wait another half sec after the fade out is completed
xor a
ld (mfade),a ;remove the fade flag
call PLY_AKG_STOP ;and stop the music

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