I just remembered something. Can you listen to this audio file? It sounds really bad (just experimenting with sounds, it uses HG's Global Terminal sequence and Platinum's soundfonts) but it may have modulation (that is unintentional) that you are looking for. If that isn't it, I might try some other things and see how it goes.
Well, long time. I've been trying to crunch down on looping. No dice. Have you developed any kind of method to mastering this, because it certainly seems I have not. And I am going to need this for my next project, Pokemon Aqua Sapphire.
I mean the loop is controlled by writing 94 ** ** ** FF after the last rest note. However, depending on what you did to the midi, the last rest note might be loooong, so I advise changing it in hex. If you don't know how to do this I'll put a video up this weekend. My birthday's tomorrow so I'll be busy :V
It's not exactly the most simple thing in the world... But it's not the hardest, either. However, making a tool for it is probably going to be slightly difficult because you need to have the loop point call to an offset.