I worked some 14 years ago (as a freelancer)for the largest publisher in Europe (Printed Music) and this particular problem came up then - the publisher's argument was that the Midifile was in fact a binary "book" and that as such this fell under the right to "print" according to the contract that was held with the copyright holder.

This claim was however disproven as the end result or "application" was to create a sonic performance that infringed, or rather was covered under, the mechanical rights and the original publishing copyright owner.

As the company at the time had invested a significant amount of money in i) producing it's own bespoke content, ii) purchasing some midifile-producing companies in order to amass a larger repertoire and iii) spent a large amount of money marketing said repertoire this was a major problem.

To be more precise this argument took place under the GM/GS development phase, shortly before XG was introduced as the 3rd "Standard" and still holds true today - that is, the end is a reproduction of music in a sonic state, thus any midifile copyright exists in the first extent with the copyright holder.

So for instance, where a Style file or midifile is commissioned from scratch, the copyright exists with the commissioning agent or company and the exact sequence of notes created for that commission is the "song, book, composition and intellectual property."

Where a song arrangement is recreated in midifile form, the copyright again reverts to the original composer or his/her representative and a fee is paid as royalty to exploit that work, whether it be printed media, CD recording (or any other type whether it has been invented yet or not!) or indeed midifile.

Sorry to be a bore, this is my first post as such, and it's a difficult area that I'm always confronted with in my line of work on a day to day basis. . .