Scanning Laser Illumination for Roll Scanning
By Mark Fontana
To continue the recent discussion about scanning music rolls:
I found an interesting component in this month's DigiKey catalog (a mail-order electronic parts supplier). They have a visible laser diode line generator (I assume this is the kind designed for scanning barcodes at checkout counters) for $85.00, manufactured by Applied Laser Systems. This tiny little device will project a 1mm wide LINE at an 85 degree beam angle, at a wavelength of 670nm and output power of 2.5mW. Positioned just 6 inches above a page, it would create a line 11 inches long and approximately 1mm wide.
It occurred to me that this might be a good exciter lamp for scanning music rolls-- the narrow line would help ensure that the same point in time is being read across the width of the roll. Rather than using two offset fax scanner pickups directly against the paper, how about using one pickup and optically compressing the laser line onto it somewhere beneath the tracker bar? (The tracker bar would be modified to have one narrow open slit all the way across instead of the usual holes). Rough diagram:
laser line generator
|
/ \
/ \ line projected down onto music roll and through tracker bar
/ \
/ \
_______________________ music roll
======================= tracker bar
\ /
< > lens
/ \
------- fax scanner head
Of course, this is assuming that the one fax scanner has sufficient resolution for what we're trying to do. I'm skeptical that we could get these scanner heads to pump data fast enough to scan rolls at full speed. Has anyone investigated this issue yet?
In one of the recent digests, it was suggested that we should be able to scan 12 rolls an hour, if I remember correctly. No offense, but I think this is not at all realistic.
I'm involved in a project to digitally convert over 100 Pianocorder tapes into MIDI format, producing a separate MIDI file for each song/medley. The title/composer/pianist/catalog #/etc are all embedded in the MIDI files as text events. Even with semi-automatic software performing the music conversions, it takes a certain amount of time for me to key in the text information, apply it to the correct songs, listen to the files to make sure they're okay, organize the data in appropriate directories on disk, choose appropriate filenames, check the log files generated by the conversion software... There's a lot of little tasks involved, and it takes me at least an hour to scan and archive just one tape (about 40 minutes of music).
Remember, I'm just reading perfect digital data off the tapes- I'm getting the music accurately every time. Scanning real piano rolls will present a whole slew of problems... from tears, repairs, sticky tape, alignment errors... almost every roll will require some editing. What do you do about rolls that are missing their labels? You can't just do "noidea1.mid, noidea2.mid" and move on. Researching missing information like this will take time too.
The idea of someone jetting around the country with a laptop computer and portable roll scanner (that handles every known format), gradually accumulating an authoritative archive of rolls for posterity--- it's a nice idea, but there's a lot of work beyond the actual scanning itself, and that's after we get a system designed and built. We really ought to look into what funding might be available for this project. |
(Message sent Thu 4 Jan 1996, 06:35:14 GMT, from time zone GMT-0500.) |
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