Piano-roll analysis reports

This repository contains detailed roll image analyses that is output from the roll-image-parser software. Analyses are found in the analysis directory. Filenames for each analysis report is based on the Stanford Libraries' DRUID (Digital Repository Unique ID), and are sorted into subdirectories based on the first letter of the DRUID. Files are compressed with bzip2 and can be uncompressed with bunzip2 file.txt.bz2 which will uncompressed to file.txt. Unix command-line viewing can be done with the command bzcat file.txt.bz2 | less. Uncompressed files are plain text in the ATON format and can be converted to JSON data with the ATON javascript library (see command-line utility aton2jon). These files are also found in the same DRUID entry as the roll scans.

Components of the anslyses

Each file contains these sections:

• Parameters — Information extracted from the image (see table below).
• HOLES — List of holes sort in time from beginning to end of roll.
• BADHOLES — List of automatically identified bad holes that were rejected from the HOLES list.
• BASS_TEARS — List of tears on the bass side of the roll, sorted by size.
• TREBLE_TEARS — List of tears on the treble side of the roll, sorted by size.
• SHIFTS — Analysis of horizontal operator shifts along the length of the roll.
• DRIFT — Horizontal drift analysis reported for every 0.1px shift in the roll image along the length of the roll (only during region where there are musical holes).
• MIDIFILES — Two MIDI files encoded as ASCII text using the binasc encoding of HEX bytes. The first MIDI file removes bridging (but does not do any time corrections for the edges of holes), and the second MIDI file contains a MIDI note for each hole (not reducing bridging).
• DEBUGGING — Contains an analysis of the localization of vertical tracker bar positions along the roll.

BADHOLES, BASS_TEARS, TREBLE_TEARS, SHIFTS, DRIFT, and DEBUGGING information is given in a visual form in the image analysis section of https://supra.stanford.edu (Click on the IA entry for a roll to see these analyses), such as for roll xq762nt7491.

Extracted parameters

Parameter name	Example	Meaning
DRUID	xq762nt7491	Stanford Libraries Digital Repository Unique ID
ROLL_TYPE	welte-red	Brand/format of the piano roll
THRESHOLD	249	Threshold byte value for non-paper boundary
LENGTH_DPI	300.25ppi	Scan DPI resolution along the length of the roll
IMAGE_WIDTH	4096px	Width of the input image in pixels.
IMAGE_LENGTH	391320px	Length of the input image in pixels.
ROLL_WIDTH	3898.31px	Measured average width of the piano-roll in pixels.
HARD_MARGIN_BASS	31px	Pixel width of the margin on the bass side of the roll where the roll paper never enters.
HARD_MARGIN_TREBLE	140px	Pixel width of the margin on the treble side of the roll where the roll paper never enters.
MAX_BASS_DRIFT	28px	Maximum range of the "soft" margin on the bass side: the margin area where the roll edge will temporarily enter.
MAX_TREBLE_DRIFT	26px	Maximum range of the "soft" margin on the treble side: the margin area where the roll edge will temporarily enter.
AVG_SOFT_MARGIN_SUM	26.69px	Average sum of the bass and treble soft margins.
DRIFT_RANGE	21.5px	Total drift range in pixels.
DRIFT_MIN	8.73px	Leftmost drift from average position in pixels.
DRIFT_MAX	-12.76px	Rightmost drift from average position in pixels.
PRELEADER_ROW	2620px	Last pixel row of the portion of the image which contains the velcro strap that initially pulls the roll.
LEADER_ROW	4744px	Last pixel row of the leader (although text on the roll may continue).
FIRST_HOLE	23704px	Pixel row of the first musical hole.
LAST_HOLE	387015px	Pixel row of the end of the last musical hole. Currently includes rewind holes and any punches after the rewind.
END_MARGIN	4305px	IMAGE_LENGTH - LAST_HOLE.
MUSICAL_LENGTH	363311px	Pixel row count from the first music hole to the end of the last music hole.
MUSICAL_HOLES	20503	Estimated number of intentional holes to be read by the tracker bar.
MUSICAL_NOTES	11257	Number of notes after grouping chained holes (expression tracks count as notes in this census).
AVG_HOLE_WIDTH	19.32px	Average width of a musical hole in pixels (based on holes' bounding boxes).
ANTIDUST_COUNT	86	Number of holes in the paper with an area less than 50 pixels (the smallest music holes typically have 300 pixels)
BAD_HOLE_COUNT	4	Number of suspcious holes pulled out for further observation.
EDGE_TEAR_COUNT	3	Number of edge tears which are deeper than 1/10 of an inch.
BASS_TEAR_COUNT	3	Number of tears on the bass register side of the roll.
TREBLE_TEAR_COUNT	0	Number of tears on the treble register side of the roll.
DUST_SCORE	81ppm	Count of dust particles in hard margin regions in units of parts per million.
DUST_SCORE_BASS	89ppm	Dust particle count in bass register margin.
DUST_SCORE_TREBLE	73ppm	Dust particle count in bass register margin.
SHIFTS	2	Number of automatically detected operator shifts greater than 1/100th of an inch over 1/3 of an inch.
HOLE_SEPARATION	37.8099px	Distance between muiscal hole centers (i.e., the tracker bar hole spacings).
HOLE_OFFSET	18.8502px	The offset of the tracker bar spacing pattern with respect to the first column of the image.
TRACKER_HOLES	100	The (esitmated) number of tracker bar holes that reads this roll.
SOFTWARE_DATE	Mar 26 2019 16:32:26	The compiling date for the software that generates this file.
ANALYSIS_DATE	Sun Apr 7 16:04:52 2019	The date that the analysis was done.
ANALYSIS_TIME	78.15sec	The duration of the analysis phase of the software (excluding loading of the image data or writing the analysis overlay onto the image).
COLOR_CHANNEL	green	The color channel used to generate this analysis data.
CHANNEL_MD5	c4146a3ff5cb998aff628d4934380f97	The MD5 checksum of the color channel pixels used in this analysis.
BRIDGE_FACTOR	1.37	Aspect ratio merging distance for adjacent holes.
MANUAL_EDITS	no	Set this field to "yes" if any manual edits are made to this file.