My perforating setup is fully equipped to cut new rolls from MIDI
files, and I'm happy to do one-off batches of four rolls!  To keep
things really simple there's a flat price of GBP 8 each up to 30 feet
long (plus post at cost from the UK).

Although it's apparently easy to convert MIDI to rolls there are
actually quite a lot of ways of going wrong, both in interpreting the
MIDI itself and in how it is converted to roll.  Accurate conversion
of MIDI to rolls involves getting all the details correct.  I decided
to try and do this as well as possible, rather than a simplistic "one
size fits all" approach, and it took months of work on my software so
that most Type-0 or Type-1 MIDI files will convert into rolls.  Results
are better from MIDI files constructed with rolls in mind, but most
work well enough.

Probably the hardest thing to deal with is overlapping notes in the
MIDI file, needed for orchestral performances but clearly impractical
for pianos.  Many MIDI files -- even of plain piano music -- have
overlaps.  Some are over-length notes where one starts before the
previous one ends, while others appear to arise from sloppy editing
or poor software where notes get copied on top of themselves so that
there are several identical events at or near the same time.  In a
Type-1 MIDI file these may be in different tracks.  Coping with all
the possibilities gets very complex indeed!

Note timing can either be built directly into the notes themselves
(such as by recording a live performance) or can be constructed by
putting MIDI tempo events into music created directly from sheet music.
The resulting event times can then be converted either 'analogue', by
rounding to the nearest punch row with resultant slight timing errors,
or the MIDI-file 'ticks' (internal timing counters) can be scaled
directly into punch rows.  If scaling is done properly each note in
the MIDI file converts to a whole number of rows so each perforation is
at exactly the right point with no timing error, ideal for fixed-tempo
music (i.e., almost all popular music rolls).  Compensation for the
acceleration in paper speed as the roll progresses can be built-in for
the analogue conversion but not for direct scaling.

You also need to consider player-piano issues.  One is a minimum gap
between notes so the player and piano mechanisms have time to reset,
allowing for the fact that there may be no gap whatsoever in the MIDI
file.  Another is that the slot length needs to be shortened slightly
to compensate for the perforation/tracker bar hole interaction that
extends the note's playing time a little.  This matters quite a lot in
staccato music such as jazz, where even small differences have a marked
impact on the musical effect.

The final thing is to consider aspects of the roll that are not known
in MIDI, such as Themodist accents and perforation patterns.  To
serious player-pianists these details make all the difference between
an unplayable mess and a properly musical roll.  I offer facilities
to choose the overall perforation pattern, with modification for
individual notes so that (for instance) melody lines can be indicated
with slots as seen in Aeolian's Themodist rolls.  With a proper
perforation-level editor you can do things such as delaying notes by
a punch row or two so that individual notes can be accented in a chord.

To get back to the original question, I would like to imagine that
a composer would be interested in all of the aspects covered above,
to give a roll that is the best representation possible of the music.
To that end they should use the software to do the conversion
themselves and get the roll right to their satisfaction.

Julian Dyer