How a Computer Can Calculate A Tune's Difficulty (using BWW files)
A tune's difficulty can be measured in potential fingerwork errors per second (PEPS).
For example, a Tune A that lasts 60 seconds with 180 possible fingerwork errors has a rating of 3 PEPS. Tune B, lasting 30 seconds with 60 errors, would have 2 PEPS. Therefore, Tune A is more difficult than Tune B. Easy!
What are Potential Fingerwork Errors?
Before Dojo fingerwork methodology, it was hard to quantify specific errors. Now it's straightforward. Potential errors include:
- Missing a rhythmic target (beat/off-beat)
- Crossing noises
- Gracenote size errors (too big or missed)
- Gracenote sync errors (not aligned with note changes)
- Incorrect embellishment steps
- Embellishments not played ASA(m)P (evenly)
- Dot-cut rhythms where the cut note is not played ASA(m)P
Bagpipe Music Writer Code
Bagpipe Music Writer (BWW) is a way to programmatically document tunes. Below is a sample from "The Abercairny Highlanders":
& sharpf sharpc 2_4 I! dbe E_8
! gg LAr_16 'la Bl_32 grp Cr_16 'c Dl_32dbe Er_8 dbha HAl_8
! hdbf Fr_8 gg Dr_16 'd Fl_32 space dbe Er_8 gg LAr_16 'la El_32
! dbd Dr_16 'd Cl_32 dbb Bl_16 'b LAl_32 space gg LGr_16 'lg LAr_32 gg Bl_32 dg LGl_16 'lg
! dbhg HGr_8 tg Bl_8 space tar Br_8 dbha HAl_8 !t
& sharpf sharpc
LAr_16 'la Bl_32 grp Cr_16 'c Dl_32 space dbe Er_8 dbha HAl_8
! hdbf Fr_8 gg Dr_16 'd Fl_32 space dbe Er_8 gg LAr_16 'la El_32
! dbd Dr_16 'd Cl_32 dbb Br_16 'b LAl_32 space gg LGr_16 'lg LAr_32 gg Bl_32 Dl_16 'd
! dbc Cr_8 eg LAl_8 space brl LAr_8 dbha HAl_8 !t
Cleaned-up version (post transformation):
2_4 ! dbe E_8
! gg LA16 B32 grp C16 D32 dbe E8 dbha HA8
! hdbf F8 gg D16 F32 dbe E8 gg LA16 E32
! dbd D16 C32 dbb B16 LA32 gg LG16 LA32 gg B32 dg LG16
! dbhg HG8 tg B8 tar B8 dbha HA8
! LA16 B32 grp C16 D32 dbe E8 dbha HA8
! hdbf F8 D16 F32 dbe E8 gg LA16 E32
! dbd D16 C32 dbb B16 LA32 gg LG16 LA32 gg B32 D16
! dbc C8 eg LA8 brl LA8 dbha HA8
Embellishment Transformation Table
| Embellishment | Expansion |
|---|---|
| dbe | gg E32 fg |
| grp | LG32 dg LG32 |
| dbha | HA32 gg |
| hdbf | F32 gg |
| dbd | gg D32 eg |
| dbb | gg B32 dg |
| dbhg | gg F32 |
| tar | LG32 dg LG32 eg |
| dbc | gg C32 dg |
| brl | strlg LA32 strlg |
With embellishments transformed, the final code looks like:
2_4 ! gg E32 fg E_8
! gg LA16 B32 LG32 dg LG32 C16 D32 gg E32 fg E8 HA32 gg HA8
! F32 gg F8 gg D16 F32 gg E32 fg E8 gg LA16 E32
! gg D32 eg D16 C32 gg B32 dg B16 LA32 gg LG16 LA32 gg B32 dg LG16
! gg F32 HG8 tg B8 LG32 dg LG32 eg B8 HA32 gg HA8
! LA16 B32 LG32 dg LG32 C16 D32 gg E32 fg E8 HA32 gg HA8
! F32 gg F8 gg D16 F32 gg E32 fg E8 gg LA16 E32
! gg D32 eg D16 C32 gg B32 dg B16 LA32 gg LG16 LA32 gg B32 D16
! gg C32 dg C8 eg LA8 strlg LA32 strlg LA8 HA32 gg HA8
Analysis Metrics
Rhythmic Targets
- User input: Rhythmic targets per bar (e.g. 4)
- User input: Number of incomplete bars (e.g. 1)
- Calculated: Total Bars = (Count of bar pairs) - incomplete bars
- TotalRhythmicTargetErrors = Rhythmic targets per bar × Total Bars
Crossing Noises
- Note changes = count of unique capital letters in sequence
- Subtract exceptions (e.g., LA:B, C:D)
- TotalScaleNavErrors = note changes - exceptions
Gracenote Size & Sync Errors
- Size: Count gracenotes (e.g., gg, dg, fg, etc.)
- Sync: Gracenotes during note change = potential sync error
ASA(m)P Errors
- User input: ASA(m)P max note value (e.g. 32)
- Count notes with that value or less
- TotalAsampErrors = count of ASA(m)P notes
Total Errors Calculation
totalErrors = totalRhythmicTargetErrors + totalScaleNavErrors + totalGracenoteSizeErrors + totalGracenoteSyncErrors + totalAsampErrors
Determine Tune Duration
- User input: Targets per minute (e.g. 160)
- totalSeconds = totalRhythmicTargetErrors × (60 / targetsPerMinute)
PEPS (Potential Errors Per Second)
pepsScore = totalErrors / totalSeconds