Julie Porter wrote:

> MIDI is further obfuscated in that there are many parts to the
> standard.  The two best known are the MIDI wireline protocol and
> the SMF (Standard MIDI File) file exchange format.  There is
> a lot of confusion here that the two things are one and the same
> -- they are not! ...

I like to warn users that the biggest difference between MIDI wire
protocol and SMF is that SMF includes an artificial notion of "tracks",
analogous to multi-track studio tape recorders.

The MIDI wire protocol has no tracks, but 16 "channels" that can each
be playing a different instrument sound.  An SMF file usually maps each
of its tracks onto a MIDI channel, but it could feed two or more tracks
to one channel, or a track may contain notes of several channels.

SMF files definitely contain the note on/off information, much like
the beginning and end of each perforation on a music roll.  SMF files
are just the latest in the sequence of [data storage media such as]
barrels, books, rolls, etc.  But less fun to watch!

Each note-on event does contain a velocity (which organs ignore but
pianos could use), which determines the volume.  There is also an
overall volume control, per channel, independent of the velocities;
this is what could operate organ swell shutters, or reproducing piano
vacuum controls (though that really relates to velocity).

Trying to make a whole studio or stage full of MIDI players wireless
would indeed be a mess, though wireless MIDI devices do operate on
several separate frequencies.  Most useful setup would be one wireless
link from the  keyboard or sequencer, to one receiver with the
instruments, which would be  cabled together as usual.

Just my thoughts
Mike Knudsen