Tip: Take advantage of easy to install Patches in your hack. The No More Sprite Tile Limits or SA-1 patches should be considered if you're encountering glitches where Mario and/or sprites are turning invisible.
I had this exact same problem but I decided to leave it for later and maybe make custom music with SM64 instruments instead. You're using sound-ripper tool, right?
Maybe the program tries to create all of the sounds the music creates, but the soundfont is too different and it becomes difficult to make the sounds, which prolongs it. Try using music from another N64 game and see if it helps.
can you post an example? both the midi file and m64 file please. it might be fixable just by changing the tempo value in the m64, but I suspect it might have to do with the ticks per beat setting in the midi header.
Looks like the problem is as I thought, the resolution (PPQ) of the midi is very high and somewhat unusual (1024 instead of 480) and it looks like the converter tried to deal withh this by making the notes longer and the tempo faster, but for it to be at the proper speed the tempo would need to be higher than the tempo cap of 255 beats per minute.
I converted the midi to 480 ppq for you here. Try it out and see if the converter likes that one better.
I tried the MIDI you gave me and no dice yet.
I'll try to lower the PPQ more (to about 96) to see if it will work.
EDIT: No matter how low I lower it, it still goes very slow. Maybe it's MuseScore and its xml importing.
Okay, yeah I stand corrected, it isn't the PPQ. It seems to be an issue with the newest version of the level importer (or maybe other recent versions as well). I tried it in the oldass standalone version of the xml importer on frauber's site and there's no tempo issue. This is with an xml file i exported from rosegarden, not musescore, so it likely isn't an issue with your specific xml file. I'd recommend you try a slightly older importer and see if that does the job before you go all the way back to frauber's tho, cuz it has some issues of its own.
As I said, you shouldn't use it if you can avoid it, try some previous versions of skelux's level importer first. The version I used is the one in the tools section, which I happened to have and decided to try out, but it's pretty old and you're better off using something newer. skelux made a bunch of fixes.
Oh. It actually can't do 128th notes without having to increase the tempo and all the other note durations. It only has 48 ticks per quarter note, so it can do 64th notes, and then it can do 128th-note triplets but not normal 128th notes. So what you should do is double the duration of all the notes, and then double the tempo to turn the 128th notes into 64th notes. The current tempo is 120 bpm right? The cap is 255 so doubling it should be fine.
I already tried that before I posted this thread. It still yielded the same result. I think I'll just remake the MIDI. All I did was download the MIDI from VG Music and separate all the notes into different tracks.