tabr

Author: Matthew Leonawicz License: MIT

Overview

Create guitar tablature (“tabs”) from R code with tabr. The tabr package provides programmatic music notation and a wrapper around LilyPond for creating quality guitar tablature.

tabr offers functions for describing and organizing musical structures and wraps around the LilyPond backend. LilyPond is an open source music engraving program for generating high quality sheet music based on markup syntax. tabr generates files following the LilyPond markup syntax to be subsequently processed by LilyPond into sheet music.

A standalone LilyPond (.ly) file can be created or the package can make a system call to LilyPond directly to render the guitar tablature output (pdf or png). While LilyPond caters to sheet music in general, tabr is focused on leveraging it specifically for creating quality guitar tablature.

Functionality and support

The tabr package offers the following:

• Render guitar tablature and sheet music to pdf or png.
• Write accompanying MIDI files that can respect repeat notation and transposition in the sheet music (under reasonable conditions).
• Support tablature for other string instruments besides guitar such as bass or banjo.
• Support for instruments with different numbers of strings.
• Support for arbitrary instrument tuning.
• Offers inclusion (or exclusion) of formal music staves above tab staves, such as treble and bass clef staves for complete rhythm and timing information.
• Track-specific setup for features like instrument type, tuning and supplemental music staves.
• Provides common notation such as slide, bend, hammer on, pull off, slur, tie, staccato, dotted notes, visible and silent rests.
• Allows arbitrary tuplet structure.
• Above-staff text annotation.
• Percent and volta repeat section notation.
• Note transposition.
• Staff transposition.
• Multiple voices per track and multiple tracks per score.
• Chord symbols above staff
• Chord fretboard diagrams and chord chart at top of score.
• A variety of layout control options covering settings from score attributions to font size.
• Optional alternative input format allowing the user to provide string/fret combinations (along with key signature and instrument tuning) to map to pitch.

Note that MIDI support and string/fret alternative input format support are not prioritized in ongoing tabr development. These are considered tangential extra features in tabr that fall outside the general scope and intent of the package.

In additional to the R to LilyPond sheet music pipeline, tabr also offers a large collection of functions to support general music programming operations.

Installation

You can install tabr from CRAN with:

install.packages("tabr")

You can install tabr from GitHub with:

# install.packages("remotes")
remotes::install_github("leonawicz/tabr")

Basic example

As a brief example, recreate the tablature shown in the image above (minus the R logo). Here are the steps.

• Define a musical phrase with phrase or the shorthand alias p.
• Add the phrase to a track.
• Add the track to a score.
• Render the score to pdf with tab.

The code is shown below, but first some context.

Constructing a musical phrase

A phrase here does not require a strict definition. Think of it as the smallest piece of musical structure you intend to string together. The first argument to phrase is a string describing notes of a specific pitch (or rests: “r”), separated in time by spaces. For chords, just remove spaces to indicate simultaneous notes. Integers are appended to indicate the octave number so that the pitch is unambiguous. For example, a rest followed by a sequence of notes might be given by notes = "r a2 c3 f3 d3 a3 f3".

The second argument is a similar string giving note metadata. In this example there is nothing to add but the time durations. Whole notes taking up an entire measure of music are given by 1, half notes by 2, quarter notes 4, eighth notes 8, and so on. To specify a quarter note rest followed by a sequence of eighth notes, use info = "4 8 8 8 8 8 8" (or shorten to just info = "4 8*6"). This basic example does not require specifying additional note information such as dotted notes for different fractions of time, staccato notes, ties/slurs, slides, bends, hammer ons and pull offs, etc. These specifications are currently available in tabr to varying degrees of development and are covered in the vignette tutorials.

The third argument, string, is optional but generally important for guitar tablature. In similar format, it specifies the strings of the guitar on which notes are played. Providing this information fixes the fret-string combinations so that LilyPond does not have to guess what position on the neck of the guitar to play a specific note. An inability to specify this in various tablature notation software (or laziness by the user), is a common cause of inaccurate tabs scouring the internet, where even when the notes are correct they are written in the tab suggesting they be played in positions no one would sensibly use. Note that the x shown below is just a placeholder indicating no need to specify a string for the quarter note rest.

The example below employs a couple shortcuts to further reduce typing. The first is to use the * in-string expansion operator mentioned above to avoid typing a long series of eighth notes. Second, it drops explicit reference to octave number three since this central octave is the default octave in LilyPond. This applies to all but the first note below.

While explicit string numbers are not needed for this example, they are provided anyway for full context. Dropping the string argument would further reduce typing.

Score metadata and accessing LilyPond

Finally, specify some song metadata to reproduce the original staff: the key of D minor, common time, and the tempo.

If LilyPond is installed on your system (and added to your system path variable on Windows systems), tab should call it successfully. Windows users are recommended to just add LilyPond’s bin directory to the system path. This will take care of LilyPond as well as its bundled Python and MIDI support. As an example for Windows users, if the LilyPond executable is at C:/Program Files (x86)/LilyPond/usr/bin/lilypond.exe, then add C:/Program Files (x86)/LilyPond/usr/bin to the system path.

R code

library(tabr)

p("r a2 c f d a f", "4 8*6", "x 5 5 4 4 3 4") %>% track %>% score %>%
  tab("phrase.pdf", key = "dm", time = "4/4", tempo = "4 = 120")

#> #### Engraving score to phrase.pdf ####
#> GNU LilyPond 2.18.2
#> Processing `./phrase.ly'
#> Parsing...
#> Interpreting music...
#> Preprocessing graphical objects...
#> Interpreting music...
#> MIDI output to `./phrase.mid'...
#> Finding the ideal number of pages...
#> Fitting music on 1 page...
#> Drawing systems...
#> Layout output to `./phrase.ps'...
#> Converting to `./phrase.pdf'...
#> Success: compilation successfully completed

See the pdf result embedded at the tabr website.

Note above that tabr also exports the pipe %>% operator. Even given the hierarchy of objects involved in the series of steps to move from a phrase to a rendered pdf, a short example like this does not even require a single assignment. While music can be quite complex and a full score will be much longer, tabr strives to minimize the work while still forcing some sense of interpretable, organized structure. For long and complex music, it can require some effort and practice to ensure your approach to transcription in your R code is not opaque.

Additional context

Why LilyPond? LilyPond is an exceptional sheet music engraving program.

• It produces professional, high quality output.
• It is open source.
• It offers a command line access point for a programmatic approach to music notation.
• It is developed and utilized by a large community.
• Most GUI-based applications are WYSIWYG and force a greater limitation on what you can do and what it will look like after you do it.

Limitations

This package is not intended to access all LilyPond functionality from R. If your transcription needs are that great, just use LilyPond directly. However, when working in R, tabr gives you programmatic access to LilyPond that is quite valuable.

New in v 0.3.0: more music programming support

Version 0.3.0 of tabr adds many new helper functions. These functions do not directly impact the tabr-LilyPond sheet music pipeline. They expand music programming with tabr more generally and can be used without LilyPond installed. LilyPond is only required for sheet music engraving. So even if you do not need to create tabs from R code, the broader suite of tabr functions may be useful to you.

Note: I was hopeful that this version of tabr would be able to leverage a new, native bend engraver in LilyPond, but it appears that on the LilyPond side this development has not progressed since I last checked.

References and resources

There is a rich collection of vignette tutorials and examples as well as complete package documentation available at the tabr website.

R-Music

R for music data extraction and analysis

See the R-Music organization on GitHub for more R packages related to music data extraction and analysis. The R-Music blog provides package introductions and examples.

Other packages

• The tuneR package for analysis of music and speech by Uwe Ligges, Sebastian Krey, Olaf Mersmann, and Sarah Schnackenberg.