WEB file format is a record of the location of the holes in the music
roll.  Its purpose is to control a perforator which has all the punches
lying along a straight line.  The WEB file is creating by transcribing
the music roll using a linear hair-line height tracker bar or a line
scanning camera.

BAR format is intended to control a pneumatic player action using
magnet valves, and so it represents the motion of the valves in
the player piano.  Thus the data must account for the size and
vertical location of the holes in the tracker bar.  For example,
if the tracker bar of the instrument has offset holes, like the
Duo-Art, then the in-line perforator data of WEB format turns on
the control valves much too late.

To overcome this problem Wayne Stahnke created the BAR data format,
which is the cross-correlation of the perforator data with the image of
the tracker bar of the target instrument.  The BAR file is a derivative
of the WEB file.

The data structure of WEB and BAR files is identical; as far as I know
either format can be opened and read with a programs such as "Wind" or
"WindPlay" by Richard Brandle.

The associated ANN (annotation) file defines the units of distance and
paper speed for playback, etc.  Each data record of the file contains
a field telling the long-axis ("time" axis) position, followed by a
second field which toggles the channel on and off.

Some BAR files (but not WEB files) incorporate Tempo compensation using
an assumed take-up spool diameter or acceleration constant declared in
the ANN file.  I think this is usually for long classical rolls, not
for pop rolls which were intended for constant metronome beats per
minute.

The WEB (or BAR) file format supports up to 240 channels, so it's
suitable for the widest player organ rolls.  Meta channels are provided
to store control events and text events such as lyrics.

In the article "Re: Stahnke Roll Archival Methodology", in MMDigest
96.03.07, Wayne Stahnke wrote:

"The specification for the data format is embodied in a C language
driver file called ROLLFILE.C that you can get from Jody Kravitz
(just send him a note on the digest or at rollsreq@foxtail.com)."

See http://mmd.foxtail.com/Archives/Digests/199603/1996.03.07.06.html

I'll send you separately the current version (v10.00) of file
ROLLFILE.C (35 kb).  It's an ordinary DOS text file so it may be viewed
using any text editor.  For convenience with Windows you can rename
the file to ROLLFILE.C.txt if you wish.

Please tell me your impressions of the information, because I'm sure
others will write to me or MMD with questions about the process.

Best regards,

Robbie Rhodes