fade in/out transitions for sound?

[mobichan]

I was wondering if there is a simple way to fade one music/sample into another. In my game, I am going to loop a sample for most of the level, but when you reach a part of the level (to fight a boss, let's say) I want to be able to fade out the loop wherever it is and then fade in the boss fight music.

[Popcorn]

Yes, check out the sound actions. You have full control over the sound channels. Set the channels' volume relative to counters and you can make your own fade in/out

[Jdsfrog]

What I usually do when I want a fade in/out is just set an alterable value called whatever you want(Eg. Fade), then do a "Set volume of specific sample", and make it relative to your Fade value. Then you can put an event in a group of events and make it something like:
Group (Fade In/Out)

Every .15 seconds| Add to alterable value (Fade) 1

Then when you want it to stop you could just say like whenever Fade value equels eg. 50, deactivate group Fade In/Out.(If you want a fade out, set the value's intial value to whatever, then subtract instead of add) Although Popcorn's idea is way more simpler.