GITI
– Electric guitar music text format

Summary

This is a description/specification of GITI (variant E) – Guitar Instrument Text Interface (electric) – version 4.1: an electric guitar music notation text format.

GITI is concise, expressive, and usable by both humans and software. The format is in ASCII text (so also UTF-8). (File-name suffix could be: .giti or: .giti.txt .).

Traditional musical notation is powerful and general, but rather mechanically complex and demanding (despite its aesthetic recompense). Guitar tabs are better focused, but with obvious weaknesses and still awkward to read automatically and write manually. GITI follows the specialisation of tabs but flattens them into a more manipulable word-like form, and redeems the larger shortfall by adding a traditional kind of time information – all somewhat inspired by the event-packet basic form of MIDI. But it can also be rendered in familiar quasi-graphic tab form.

This version does not cover vibrato-bridge use or complex parallelism. The former might be an easy addition, but the latter would need more design and adjustment.

Contents

• Summary
• Piece
  • Sound
    • Act
      • basics
      • extras
    • Pitch
      • basics
      • extras
    • Time
      • basics
      • extras
  • Indicator
    • Bar
    • Segment
    • Tuplet
  • Annotation
    • Version
    • Tuning
    • Tempo
  • Metadata
  • Comment
• Tab
• Appendix
  • Tools
  • Changes

Piece

A whole Piece is a string of Sounds, Indicators, Annotations, and Comments. Sounds and indicators are blank-separated tokens, and annotations and comments are special lines.

As a brief overview, consider this ordinary tab:

Black Sabbath ‘Black Sabbath’, main riff

|--------|-------------|
|--------|-------------|
|--------|-------------|
|------5-|-------------|
|-5------|-4r1----4/10-|
|-3------|-------------|

In GITI it is (note first how the 3, 5, 4 fret-numbers are prepended with their string-number):

# Black Sabbath ‘Black Sabbath’, main riff
@ giti:e-4.1  tuning:std  tempo:3.603 

|4  63=55:2 ' 45 |
|   54r1:2**e  s:54/10:8s |

The format also allows degrees of simplification: omitting chords, ornament, articulation (second line), and time, down to only pitch (third line):

63=55:2  45  54r1:2**e  s:54/10:8s
63:2     45  54:1
63       45  54

And GITI can also be rendered back into tab-form including all its extras (actuation above, time below):

# Black Sabbath ‘Black Sabbath’, main riff
@ giti:e-4.1  tuning:std  tempo:3.603 

#=                  s     
#= |---------|-----------|
#= |---------|-----------|
#= |---------|-----------|
#= |-------5-|-----------|
#= |---5-----|-4r1--4/10-|
#= |---3-----|-----------|
#= |4: 2 ' 2   2**e 8s    

The following sections will explain the details.

(piece
   (* (| content
         annotation
         metadata
         comment
         blankline)))

(content
   (, (* blank)
      (+ (| sound
            indicator)
         (+ blank))
      (* blank)
      newline))

Sound

A Sound has three parts:

• Act – actuation related (starting the string vibrating),
• Pitch – frequency related,
• Time – duration related,

separated by colons. For example: pluck string 5 fret 4 with vibrato for a quarter-note:

p:54v:4

Or more complex: a unison-bend, into a slide:

p:314>2=212:4e  s:314/21

Simplification

Simplified uses can omit either or both act and time:

p:54:4
54:4
p:54
54

(Two other, secondary, sound forms – continuation and rest – will be described later in the time sub-section.).

(sound
   (| ordinary
      continuation
      rest))

(ordinary
   (, (? (, act ":"))
      pitch
      (? (, ":" time))))

(continuation
   (, "&" (? (, ":" time))))

(rest
   (, "." (? (, ":" time))))

(act
   (, (? actbasic)
      (? actextra)))

(actbasic
   (| "p" "h" "u" "w" "s" "t" "i" "f" "b" "e" "m"))

(actextra
   (, (? (| "$" "%"))
      (? (| "+" "-"))
      (? (| "<" ">"))))

(pitch
   (+ (, pitchbasic
         pitchextra)
      "="))

(pitchbasic
   (| stringfret
      scorenote))

(stringfret
   (, int1-9 int0-24))

(scorenote
   (, (| "A" "B" "C" "D" "E" "F" "G")
      (? (| "#" "b"))
      int0-8))

(pitchextra
   (, (? (| (, ">" (| "?"
                      (, int1-5 (? "?"))))
            (, "<" (| "?"
                      (, int1-5 (? "?"))))
            (, "/" int0-24)
            (, "\\" int0-24)))
      (? (| "v"
            (, "r" (? (, (? "-")
                         int1-9
                         (? int1-9))))))
      (? (| "h"
            "i"))))

(time
   (, (? timebasic)
      (? timeextra)))

(timebasic
   (, (? "-")
      int0-999
      (| (* "*")
         (* (, "-" int1-999)))
      (? "-")))

(timeextra
   (| "e" "s"))

Indicator

Indicators are of three kinds: bar, segment, and tuplet. They are optional: all timing information is in sounds, but indicators help human users.

Bars can be indicated with lines, and optional suffix numbers for time division:

|3   |
|    |
||   ||

Segments of a bar can be indicated by a quote (to give a sort-of ersatz beaming):

|4  61:4 ' 61:4 ' 61:8 62:8 ' 61:4 | 

Tuplets can be indicated with parentheses and suffix number:

|4  .:2-4 ' (3 45:6  43:12 ) |

(NB: tuplet parentheses, like segments and bars, must be tokens – surrounded by blanks, not immediately abutting any other chars.).

(indicator
   (| bar
      tuplet
      segment))

(bar
   (, (+ "|") (? int1-9)))

(tuplet
   (| (, (+ "(") (? int1-9))
      (+ ")")))

(segment
   (+ "'"))

Annotation

An Annotation is a line starting with @, containing three possible kinds of data: version, tuning, and/or tempo.

Version (giti), followed by:

• e-4.1 – variant E, version 4.1

Tuning, followed by one of:

• std – standard: E2 A2 D3 G3 B3 E4 (assuming C4 = 261.6Hz) (default)
• -2? – -/+ semitones, and microtone
• 6D2= ... – string, pitch (multiple separated by =)

Tempo, followed by either:

• 3.603 – duration of a bar in seconds, to millisecs precision
• 4=120 – fractional note having some BPM

For example:

@ giti:e-4.1  tuning:-2  tuning:6D2=5F2  tempo:1.824

(annotation
   (, "@"
      (* blank)
      (* (| version
            tuning
            tempo)
         (+ blank))
      newline))

(version
   (, "giti:"
      (* non-blank)))

(tuning
   (, "tuning:"
      (| "std"
         (, (| "-" "+") int0-12 (? "?"))
         (+ (, int1-9
               (| "A" "B" "C" "D" "E" "F" "G")
               (? (| "#" "b"))
               (? (| "-" "+"))
               int0-8)
            "="))))

(tempo
   (, "tempo:"
      (| (, int0-99 "." int0-999)
         (, int1-99 "=" int1-999))))

Metadata

Metadata is a line starting with !, containing a name and a value (preferably according to Dublin Core).

Name – a single word (containing no space)

Value – arbitrary text (but space at ends is ignored)

Separated by an =, and with optional surrounding spaces.

For example:

! title = Opus 3 Concerto 4
! date = 2016-07-29
! language = en-GB

(metadata
   (, "!"
      (* blank) name (* blank)
      =
      (* blank) value newline))

(name
   (+ non-blank))

(value
   (, non-blank
      (* non-newline)))

Comment

A Comment is a line starting with #, containing arbitrary text.

(comment
   (, "#"
      (* non-newline)
      newline))

Tab

GITI translates very directly to familiar old quasi-graphic tab form, but it brings a more appreciable structure with the modularity of act, pitch, and time.

The original example:

# Black Sabbath ‘Black Sabbath’, main riff
@ giti:e-4.1  tuning:std  tempo:3.603 

|4  63=55:2 ' 45 | 54r1:2**e  s:54/10:8s |

can be rendered as:

# Black Sabbath ‘Black Sabbath’, main riff
@ giti:e-4.1  tuning:std  tempo:3.603 

#=                  s     
#= |---------|-----------|
#= |---------|-----------|
#= |---------|-----------|
#= |-------5-|-----------|
#= |---5-----|-4r1--4/10-|
#= |---3-----|-----------|
#= |4: 2 ' 2   2**e 8s    

Acts go along the top, times along the bottom, and pitches in the middle, with the first digit removed (and chords across lines). And as with word-form GITI, acts and times can be omitted to simplify down to pitches, and the main tab lines, alone. It is basically a 2D transpose, and a lossless conversion (in either direction).

Other details follow intuitively:

• act is on the line immediately above the string-lines
• rests must put their ‘.’ on the third string-line
• bar indicator number precedes time items
• time is on the line immediately below the string-lines
• segment and tuplet indicators go between time items
• lines start with ‘#= ’

Appendix