Why does music and FMV sound bad/distorted sometimes?
Most DS music is sequenced music, loaded from the cart entirely when the level loads. This works mostly fine, but bonus points for you if your ears are good enough to spot the bugs. Your music that doesn’t work well at all is probably streaming music, which loads from the cart on the fly and goes straight to the speakers, and possibly decoded along the way. This includes FMVs. This is much harder to emulate as it requires correct timing, which is not one of DeSmuME’s strengths right now. At any rate, in 0.9.5 support for a synchronized SPU was added for the windows builds which can be optionally enabled to make these streaming sounds work correctly. Synchronizing audio is a hard problem to solve, and we’re not finished solving it. The synchronous SPU comes with some other issues, which is why it is optional. Also available, if you are using the windows build, is a command from the menu Emulation > Shut Up to make the offending music go away.
