Hi MMDers:  Dan Wilson's point that MIDI can be used to "formulate" a
ritard is well taken.  However, reasonably sophisticated MIDI programs
will do this without so much effort.  For example, a program I've had
access to permits you to select a passage (one of the "view" formats
is, oddly, "piano roll"), and then decide whether you want to drop the
tempo of the entire selected passage, or whether you wish to taper a
ritard over the whole length of it.

If you are creating a MIDI performance (for roll manufacture) which
utilizes the features of MIDI in a metronomic fashion (i.e., you are
inputting the music in time with the MIDI beats laid down by the
computer), this is a nice technique for putting in tempi changes.
Some music rolls call for a fairly strict metronomic approach (and
making use of the uniformity of MIDI tempi as a guide is a great tool),
others can be just "input" by the artist using MIDI, and then modified
in the editing, as done with a "hand played" roll and marking piano.
It is these sorts of capabilities which leads me to believe that MIDI,
in conjunction with a roll editing program like "Wind" by Richard
Brandle or "View" by Wayne Stahnke, represents an excellent tool for
creating piano rolls.

For those of you bored by these threads on MIDI roll making, here's an
interesting tidbit:  most MIDI programs (obviously _not_ designed for
mechanical music cognoscenti) allowing editing various "views"; a very
common format for editing in many programs looks exactly like a piano
roll.  Of course, the granulation (i.e., extreme "microscopic" note
density necessary to make a roll sound smooth) for note editing is not
there in most MIDI programs, necessitating use of a roll editing
program to finalize the roll file for perforation.

Best regards,

Tim Baxter
Meliora Music Rolls