> From rollreq Mon Jun  5 22:48:24 1995
> To: mfontana@magnus.acs.ohio-state.edu
> Subject: Music scanning, etc

Mark,
   I read with some interest the conversation you are having with
Will Dahlgren (he posted a portion for the rest of the group to read.
Mike Ames and I have also build an optical scanner.  We've got the
mechanical thing under control, including building a spring-suspended
"optical bench" to decouple it from various room vibrations.  We also
designed a clever tachometer to measure the paper motion.  We've
not found a fast enough CCD camera to suit us -- the one we are using
runs at about 40 Hz, which means you have to run the paper pretty
slowly to do high-res scanning.  While some reproducing piano systems
can suffer from  cumulative errors from incorrectly computed integrals
(read Zoltan's paper), we've found found that for a lot of band-organ
and nickelodeon type material that the lower scan rate seems to work OK.

   I'd love to know what "camera" or electronics you are using for your scanner.

   On the topic of MIDI-Pianocorder conversion, a buddy of mine and I
very nearly built a PC card with an 8530 on it to drive a Pianocorder.
We belive that it is possible to program an 8530 to do that.  Care
and feeding of the 8530 in real time (Will's right, this is VERY
real-time) should be possible -- perhaps with a small on-board
fifo.  Access could be implemented as Windows "MIDI" driver with
the output actually going on out the 8530.  That would allow ANY
Windows MIDI sequencer to output to the Pianocorder directly. There's
still the issue of coupling it safely to the Pianocorder.  Since
we had access to one of Will's MC-2's, we ended up scapping the
project in favor of spending time on our scanner.

   The notion of computing (perhaps offline) output to be sent to
a sound card to drive the Pianocorder input is intrigueing.  The fellow
that I was working on the 8530 "project" with and I disucussed it and
actually think it could be done.  In fact, it should be possible to
do data _EXTRACTION_ from the cassette tapes if they were digitized.
Unless the sampling rate is synchronized (phase locked) with the signal
the sampling rate will have to be substantially higher than data rate.
Clearly 44.1KHz would be plenty.  8 bit samples would probably do fine.
Again, there's the issue of coupling the signal safely to the Pianocorder.

   There is at least one other system that I know of that recorded
music score data using "Harvard Bi Phase" so if you persued this there
might be an opportunity to attack some other material.

   I'm not convinced that there'd be any money in doing any of this, but
the techical challenge is attractive.

Jody

P.S. In the interest of keeping things "balanced" I've invited Mike Ames to write about his experiences with MIDI-pneumatic interfacing.  He's designed and had built a couple of differrent electrically operated valve designs.  These were for his Mortier Dance-hall organ and if memory serves me right the values were SPDT (Single Pole Double Throw). They were driven with Devtronix MIDI boards (I think John Grant has mentioned these before).  Devtronix MIDI boards have some current limits that can be annoying although I don't think he ever "toasted" a driver.  However, for his experiments driving a Mills Violano, he had to resort to a bufferring the ouputs from the Devtronix boards.