devkitPro

At least it seems I succeed in isolating the problem.
Scenario:
- we've got a soundbank with some XM modules and some SFX.
- there's always one module playing (looping).
- in any moment we have to stop that module and suddenly start playing another module.
- SFX (non-looping) can get triggered ...

mmm... I spoke too soon

It seems that the problem may be caused by a vblank happening while I'm stopping the old module/starting the new one, so I solved adding this: before stop/start.
I hope that's enough, and that this info would be useful to others

Looks like it's a problem that arises when I stop a module and start another... am I not supposed to start a module immediately after stopping another?
I'm trying to reproduce it in a test program...

Indeed it's the size of the internal data structure...

Quite curious: in mm_mixer_gba.s there's this:
@ MIXER CHANNEL FORMAT

.equ CHN_SIZE, 24

.equ CHN_SRC,0
.equ CHN_READ,4
.equ CHN_VOL,8
.equ CHN_PAN,9
// 10
// 11
.equ CHN_FREQ,12
.equ CHN_SIZE,16

if I'm right, the last line redefines CHN_SIZE to value 16.

But then in MaxMod.h there's
#define ...

I am using the function now to see the state of the channel(s).
Let's see if I can sort out the problem...

I tried increasing channels from 12 to 16, but the problem persists.
It really sounds like some channels get 'stuck' busy -even if not playing anything- and they never get back to the 'free' state.
The XM causing this uses volume envelopes and key-off commands... I'll try remove those and see if ...

... there's something I really don't get
Why is an 8 channels XM using more than 8 'MaxMod' channels?
AFAIK MaxMod on GBA doesn't feature "volume ramping" so I'm really puzzled.
Anyone?

It looks like when I play an XM (though it doesn't happen with every XM), it eats up all the available 'channels' and none is left for sound effects... even if the XM is using 8 channels only and MaxMod has been initialized with 12 channels.
mmInitDefault((mm_addr)soundbank_bin, 12);
Is there a ...