Mei‑friend. A viewer and last-mile editor for MEI score encodings Oleksii Sapov Mozarteum Foundation Salzburg Salzburg, Austria sapov@mozarteum.at Institut für Dokumentologie und Editorik e.V. December 2022 http://ride.i-d-e.de/issues/issue-15/mei-friend 10.18716/ride.a.15.2 https://github.com/i-d-e/ride/raw/master/issues/issue15/mei-friend/mei-friend.pdf RIDE - A review journal for digital editions and resources Anna-Maria Sichani Elena Spadini Ulrike Henny-Krahmer Frederike Neuber Martina Scholger Tools and Environments http://ride.i-d-e.de/issues/issue-15 10.18716/ride.a.15 mei-friend Werner Goebl, David M. Weigl (trompamusic) Programmer Weigl, David M. Programmer Goebl, Werner 2021 https://github.com/trompamusic/mei-friend 2022-02-06 Criteria for Reviewing Tools and Environments for Digital Scholarly Editing

born digital

 General information Software type cf. Catalogue 0.1.1 What type of software is it? Software tool Virtual Reseaerch Environment (VRE) Identification of the environment cf. Catalogue 1.4 On which platform runs the tool? Operating system Web browser Another application Purpose cf. Catalogue 1.5 For what purpose was the tool developed? developed to accomplish a general task developed for a specific project or materials Funding cf. Catalogue 1.6 Which is the financial model of the tool? Free/open Support-based Behind a paywall Maturity cf. Catalogue 1.5 What is the development stage of the tool? Release Beta Alpha Methods and implementation Programming Language cf. Catalogue 2.3 Which programming languages and technologies are used? C family Java Python PHP R Ruby XSLT Unknown Other JavaScript Reuse cf. Catalogue 2.3 Does the tool reuse portions of other existing software? Yes No Input format cf. Catalogue 2.4 Which input formats are supported? .xml .xml/tei .txt .pdf .csv .html .json .rdf Other .xml/mei Output format cf. Catalogue 2.4 Which output formats are supported? .xml .xml/tei .txt .pdf .csv .html .json .rdf Other .xml/mei Encoding cf. Catalogue 2.4 Which character encoding formats are supported? latin-1 utf-8 utf-16 Unknown Other Encoding preprocessing Is a pre-processing conversion included? Yes No Dependencies cf. Catalogue 3.2 Does the documentation list dependencies on other software, libraries or hardware? Yes No Not applicable (no documentation provided) Dependencies installation If yes, is the software handling the installation of dependencies during the general installation process (you don't have to install them manually before the installation)? Yes No Not applicable (no documentation provided) Documentation and support Documentation cf. Catalogue 3.4 Is documentation and/or a manual available? (tool website, wiki, blog, documentation, or tutorial) Yes No Documentation format cf. Catalogue 3.3 Which format has the documentation? readme .txt .html .pdf Not applicable Other Documentation parts cf. Catalogue 3.3 Which of the following sections does the documentation contain? ‘Getting Started’ section (installation and configuration) Step-by-step instructions Examples Troubleshooting (a selection of possible error messages and related solutions) FAQ Support API documentation (if relevant) Not applicable Documentation language cf. Catalogue 3.3 In what languages is the documentation available? Arabic Chinese Danish English Finnish French German Greek Hebrew Hindi Italian Japanese Latin Norwegian Polish Portuguese Russian Spanish Swedish Turkish Not applicable Other Support cf. Catalogue 3.4 Is there a method to get active support from the developer(s) or from the community? Yes No From of support cf. Catalogue 3.4 Which form of support is offered? Help desk Forum Mailing-list Not applicable (if no support is given) Other Issue tracker cf. Catalogue 3.4 Is it possible to post bugs or issue using issue tracker mechanisms? Yes No Usability and sustainability Build and install cf. Catalogue 3.6 Grade how straightforward it is to build or install the tool on a supported platform: straightforward normal tricky Tests cf. Catalogue 3.7 Is there a test suite, covering the core functionality in order to check that the tool has been correctly built or installed? Yes No Portability and interoperability cf. Catalogue 3.8 On which platforms can the tool/software be deployed? Linux/BSD/Unix Mac OS X Android iOS Windows Not applicable (if web-based for example) Other Devices cf. Catalogue 3.8 On which devices can the tool/software be deployed? Desktop Laptop Smartphone Tablet Smartboard Unknown Not applicable (if web-based for example) Other Browsers cf. Catalogue 3.8 If the tool is web-based: On which browsers can the tool/software be deployed? Mozilla Firefox Google Chrome Safari Unknown Not applicable (if not web-based for example) Other Plugins cf. Catalogue 3.8 If the tool is web-based: Does the tool rely on browser plugins? Yes No Not applicable API cf. Catalogue 3.8 Is there an API for the tool? Yes No Code cf. Catalogue 3.9 Is the source code open? Yes No License cf. Catalogue 3.9 Under what license is the tool released? GNU/GPL GNU/LGPL Apache MIT Mozilla CC0 CC-BY CC-BY-ND CC-BY-NC CC-BY-SA CC-BY-NC-ND CC-BY-NC-SA No explicit license / all rights reserved Other Credits cf. Catalogue 3.9 Does the software make adequate acknowledgement and credit to the project contributors? Yes No Registered cf. Catalogue 3.9 Is the tool/software registered in a software repository? Yes No Possible contribution If yes, can you contribute to the software development via the repository/development platform? Yes No Not applicable Analysability, extensibility, reusability of the code Analysability cf. Catalogue 3.10 Can the code be analyzed easily (is it structured, commented, following standards)? Yes No Unknown Not applicable Extensibility cf. Catalogue 3.10 Can the code be extended easily (because there are contribution mechanisms, attribution for changes and backward compatibility)? Yes No Unknown Not applicable Reusability cf. Catalogue 3.10 Can the code be reused easily in other contexts (because there are appropriate interfaces and/or a modular architecture)? Yes No Unknown Not applicable Security and privacy cf. Catalogue 3.11 Does the software provide sufficient information about the treatment of the data entered by the users? Yes No Supportability and maintenance cf. Catalogue 3.12 Is there information available whether the tool will be supported currently and in the future? Yes No Citability cf. Catalogue 3.13 Does the tool supply citation guidelines (e.g. using the Citation File Format)? Yes No User interaction, GUI and visualization User profile cf. Catalogue 4.1 What kind of users are expected? Humanities researcher Computer scientist Digital humanist General public User interaction cf. Catalogue 4.1 What kind of user interactions are expected? Reading Text editing Text analysis Image editing Searching Visualization Comparing Compiling User Interface cf. Catalogue 4.2 and 0.1.1 What kind of interface does the tool provide? Graphical User Interface (GUI) Command Line Interface (CLI) Application Programming Interface (API) Visualization cf. Catalogue 4.3 Does the tool provide a particular visualizations (in terms of analysis) of the input and/or the output data? Yes No User empowerment cf. Catalogue 4.4 Is the user allowed to customize the functioning of the tool and the output configuration? Yes No Accessibility cf. Catalogue 4.5 Does the tool provide particular features for improving accessibility, allowing „people with the widest range of characteristics and capabilities" to use it? Yes No digital music edition music encoding initiative code editing musical notation rendering

Mei‑friend, a free and open-source package for the Atom text editor, enables convenient and fast rendering of music encoded in the format of the Music Encoding Initiative (MEI) including some important navigation and display options. Furthermore, it provides various functionalities for graphical editing of MEI code using rendered music notation. Mei‑friend is primarily aimed at musicologists, librarians, musicians and music enthusiasts. Users are required to have a moderate technical expertise only owing to straightforward installation and intuitive usage of the tool.
Introduction

Digital music editions can be created using the format of the Music Encoding Initiative (MEI), which “share[s] many common characteristics and development practices” https://web.archive.org/web/20220121074651/https://music-encoding.org/about. with TEI, especially those for digital editionsFor instance, the usage of the <app> element for alternatives (cp. https://tei-c.org/release/doc/tei-p5-doc/en/html/ref-app.html and https://music-encoding.org/guidelines/v4/elements/app.html) or of the <supplied> element for material “supplied by the transcriber or editor for any reason” (cp. https://tei-c.org/release/doc/tei-p5-doc/en/html/ref-supplied.html and https://music-encoding.org/guidelines/v4/elements/supplied.html). Also, there are many similar concepts in the encoding of metadata (cp. <teiHeader> and <meiHead>).. For MEI, rendering of XML code as symbolic music notation is essential during the edition process. Typically, projects using MEIFor instance, Freischuetz Digital, Marenzio Online Digital Edition, Digital Interactive Mozart Edition, Beethovens Werkstatt. create their own (web) applications where MEI is rendered. Those are mainly designed as presentation platforms and might not be very suitable as production tools, although some project-specific functionalities can be tested in these environments. The tool mei‑friend is designed for usage during the process of creating an edition, more precisely for preparing basic musical text only as no editorial-specific markup is currently possible. Music notation other than Common Western Notation might be displayed if supported by the rendering engineThe Verovio engraving library (cf. Pugin, Zitellini, and Roland, 2014).. However, no editing functionalities for working with them are available.

Mei‑friend is distributed as a free package https://web.archive.org/web/20220209081823/https://atom.io/packages/mei-friend, currently 427 downloads [01-19-2022]. for the Atom text editor https://atom.io.. It has been developed by Werner Goebl and David Weigl in order to meet the needs of the project TROMPA https://web.archive.org/web/20220210094706/https://iwk.mdw.ac.at/h2020-trompa. and was generously shared with the MEI communityThe presentation at the Music Encoding Conference 2021 received the best paper award.. The author was able to integrate the tool into his daily routine of MEI encoding very well, turning it into a more convenient and efficient processThe author has been working as research assistant at the Digital Interactive Mozart Edition (Mozarteum Foundation Salzburg) since 2018 having both editorial and technical responsibilities. He has been using mei‑friend since 2021 and its predecessor mei-tools-atom since 2020..

For this review, the following hardware/software was used: Microsoft Windows 10 Pro N, Version 21H2 (64 bit), Atom v1.58.0 x64, mei‑friend v0.6.0, running on Dell Latitude 7480 (CPU Intel Core i5-6300U, RAM 8 GB). Additionally, the installation process and basic functionalities were checked on Ubuntu 21.04 with the same Atom and package versions, running on HP ProBook 440 G4 (CPU Intel Core i5-7200U, RAM 8 GB).

Methodology

Since MEI was introduced, a number of toolsOnly the tools for working with Common Western Notation are considered here. have been developed which try to address the problem of MEI rendering in the first place as currently no notation software like Sibelius, Finale or MuseScore supports MEI natively. A few of the earliest initiatives include Verovio MEI viewer https://www.verovio.org/mei-viewer.xhtml. and MEISE https://meise.de.dariah.eu. (web-based), which can display and navigate MEI. An oXygen add-on https://github.com/music-encoding/oXygen-MEI-addon. enables rendering of MEI right in the editor, but it currently seems to work for macOS only. Further on, the Verovio-Humdrum-Viewer Sapp, 2017. https://verovio.humdrum.org. (VHV) and Verovio Editor https://editor.verovio.org. (web-based) offer functionalities for graphical editing of MEI. The former offers a relatively large amount of editing operations; however, internally VHV works with the format kern. This leads to some conversion inconsistencies when importing/exporting MEI files. The Verovio Editor processes MEI natively but only a few editing operations are currently implemented. In addition, some of the tools mentioned above offer other functionalities such as creating PDF and MIDI files, advanced rendering options, etc. The predecessor of mei‑friend is a (legacy) Atom package – mei‑tools‑atom https://web.archive.org/web/20220214130403/https://atom.io/packages/mei-tools-atom.. Although, this package offers hardly any functionalities beyond a basic display, it certainly provides a good base for further development.

None of the tools mentioned above (including mei‑friend) cannot be considered as a full-fledged editor. Therefore, a typical data acquisition method in the MEI community includes conversion from data formats originally gained by manual typesetting with a notation software mentioned above or using Optical Music Recognition. Usually, manual post-processing is needed, and this is the gap that mei‑friend aims to fill.

One of the advantages that mei‑friend offers is the user friendly rendering. In my other workflow, I use a local editor for code editing and a web-based application for rendering. This setup requires several steps to display the results. This is time and energy consuming when performed repetitively and might cause errors; for instance, because of file cashing in the browser. Mei‑friend updates the rendered notation immediately after the code has been changed. This may happen as one types in Atom (default) or after saving the file in an external editor. An additional advantage is that the page remains the same after re-rendering (in some other web applications I used, the displayed page flips to the first page of the score).

Selecting multiple elements.
As mentioned above, the conversion to MEI from other formats is currently not lossless and a broad variety of issues can occur. Some of them can be fixed by using the editing functionalities of mei‑friend. Especially useful are those for inserting the ControlEventsMusic Encoding Initiative. 2019. 1.2.2. Events and ControlEvents In MEI Guidelines (Version 4.0.1). https://music-encoding.org/guidelines/v4/content/introduction.html#eventsControlevents. (e. g. <dynam>, <slur>, <arpeggio>) as these elements establish references to Events (<note>,<chord>) by pointing to their @xml:ids. Collecting these @xml:ids manually can be a tedious and error-prone task, especially if you work with a large score like a symphony. The approach used by mei‑friend is intuitive and fast: Select the Events by clicking them in the notation window (cf. figure 1) and press a shortcut that triggers a code editing function. For instance, the shortcut ‘s’ inserts the following MEI element into its correct position in the XML hierarchy:
<slur xml:id="slur-0000000025523666" startid="#some-note-id1" endid="#some-note- id2"/> An inserted <slur> after applying the shortcut ‘s’.

Currently, mei‑friend enables inserting a subset of ControlEvents and the layer-level-element <beam>; respectively, deletion works for these elements only. The elements are inserted with a pre-defined (minimal) set of attributes and dynamically created @xml:ids. Placement attributes can be manipulated, but other attributes have to be entered manually.

Finally, mei‑friend provides a few utilities for code refactoring operations as renumbering of measures, correction of accidentals and the utility called “regenerate encoding through Verovio”. The latter adds @xml:ids where missing but should be applied with special care as some undesired code changes may occur (cf. the issue on GitHub).

Implementation

“[M]ei‑friend is written in JavaScript using the Atom package framework” (Goebl, Weigl 2021, 6). It has very little dependencies which are managed using the node package manager: jQuery and Verovio. In addition, the Atom package language‑mei is required. Using Verovio’s JavaScript toolkit, MEI is rendered to SVG and embedded into a “repositionable pane within the Atom application window” (Goebl, Weigl 2021, 6) as it would be in a browser. Likewise, some other functionalities such as page breaks, zoom etc. are based on the respective Verovio functions.

The tool accepts files with ‘xml’ and ‘mei’ extensions and UTF-8 encoding. No validation is performed natively, but dedicated XML packages may be used. Some encoding‑related warnings and errors raised by Verovio and actions on the GUI are tracked in the console of the developer toolsView > Developer > Toggle Developer Tools.. For erroneous data, depending on the error, rendered notation is displayed up to the point where the error occurs or is not displayed at all.

The performance on smallCf. https://dme.mozarteum.at/movi/file/561/001. and middle-sizedCf. https://dme.mozarteum.at/movi/file/332/002. files is high using the default settings. However, “[l]argeCf. https://dme.mozarteum.at/movi/file/550/001. MEI encodings (of about 25,000 lines and more) cause performance issues[…]” Goebl, Weigl 2021, 8. See also the detailed explanation there. including disabled XML‑syntax highlighting. Two possibilities to handle this are provided: 1) Manual updates of the rendered notation and 2) usage of the speed mode. The last is an innovation which significantly improves performance on large filesFor a detailed description of the implementation, see Goebl, Weigl 2021, 8-10.. Currently, a few limitations“Works currently only with the breaks option set to System(line) and Page and System(encoded).” Cf. the documentation page. and downsidesFor instance, the “flip-page” button shifts the score to the next page after the searched one. have to be expected.

Usability, sustainability and maintainability

The package can be installed using GUI or from CLI https://web.archive.org/web/20221215131355/https://flight-manual.atom.io/using-atom/sections/atom-packages/.. The dependencies are handled by the installation process itself; a prompt appears for installation of the Atom package language‑mei. The installation procedure is well described in the Atom package registry https://web.archive.org/web/20220209081823/https://atom.io/packages/mei-friend., which I consider to be a main documentation page.

The documentation provides an overview of the tool and its functionalities; an animated screenshotCurrently visible on GitHub only. illustrates the concepts described. Example MEI files are provided as direct download and as a link to a GitHub repository with musical works published by TROMPA. Additionally, a few MEI files can be found locally in the installation folder of the package.

No special tool support is provided, but issues can be posted on GitHub and are reviewed in a reasonable time. In addition, the developers are active members of the MEI community and can be reached through its common communication channels https://music-encoding.org/community/community-contacts.html..

The learning curve based on my experience and those of our project’s chief lecturer is rather moderate. No specialized programming skills are required. However, it is advantageous to have basic knowledge of how to work with text editors, in particular with Atom, and, of course with MEI itself. It may take some time to familiarize yourself with the keybindings and to memorize them.

Mei‑friend can be used on all platformsMac, Windows, Linux. Cf. https://web.archive.org/web/20221026021350/https://flight-manual.atom.io/getting-started/sections/installing-atom/. where Atom can be installed. However, a small bias towards macOS is present: The icons for the keybindings are macOS‑style also on Windows and Ubuntu, and not every keybinding works on these platformsFor instance, the keybinding for “Show/Hide Notation” (ctrl-shift-m). As a workaround in Atom, it is possible to create custom keybindigs, cf. https://web.archive.org/web/20221122152245/https://flight-manual.atom.io/using-atom/sections/basic-customization/..

As mei‑friend is an Atom package, the user benefits from other Atom functionalities and features such as a built-in search utility, Git and GitHub integration, other related packages, etc. In addition, Atom interoperates well with other editors. For instance, it is possible to edit the same MEI in oXygen XML editor and view the changes in the rendering pane of mei‑friend immediately after the file has been saved.

Package development takes place on a public GitHub repository https://github.com/trompamusic/mei-friend.. A README file contains documentation (same content as on the Atom package page) as well as acknowledgments to the project contributors and predecessors; the (MIT) license is linked here. No CITATION.cff https://citation-file-format.github.io. file or citation guidelines are provided.

The developers of mei‑friend informed me that the tool is currently being redeveloped and extended as a web-browser application in the context of the project Signature Sound Vienna (development takes place on another GitHub repository which is currently private). Several general improvements are planned: automatic page flipping, a wider range of rendering options (based on Verovio), GitHub integration, etc. In addition, functionalities that are specific for digital editions (such as editorial markup) might be added.

Most likely the development of a web-based version of mei‑friend will be priority and the Atom package will not be actively maintained. For users who still prefer to use the Atom package (due to the interoperability with other local editors, for example), it is important to keep the MEI rendering engine Verovio up to date. Currently, this can be done in several ways: 1) by running updates pushed by the developers, 2) by reinstalling the package 3) or by running an npm update command from the package installation folder.

User interaction and GUI

MEI code is displayed alongside a pane with rendered music notation (cf. figure 1). The music notation itself is part of the GUI as the SVG elements are clickable here. Moreover, most of them are mapped to the MEI elements in the text pane. For instance, clicking a note in the notation pane immediately shows the respective MEI element in the editor pane. This also works vice versa; however, if the focused MEI element is out of range of the currently rendered page, the page has to be flipped manually.

Toolbar.
The rendering pane provides a toolbar which is divided into the following sections (cf. figure 2): 1) Zoom and “invert colors of notation”, 2) page navigation, 3) system/page break behavior and “speed mode”, 4) update behavior (when re-rendering should be performed), 5) font selection, 6) navigation through the MEI elements, 7) “regenerate encoding through Verovio”, info for current Verovio version and toggle button for overview of keyboard shortcuts. The toolbar is not customizable. A reason for customization could be that some functions would not be used very often and can be hidden, for example the “invert colors of notation”. Somewhat irritating is the “speed mode” checkbox as it is unchecked and cannot be checked by default. However, the documentation explains that the checkbox depends on the notation break option. Otherwise, the toolbar is well structured and in line with common visual patterns including tooltips.

Overview of the keyboard shortcuts.
Most user interaction happens in the music notation itself. As mentioned in the Methodology section, users can select one or more graphical elements by clicking them and applying a command. The overview of the keybindings (cf. figure 3) can be toggled with the notation pane. The list is arranged in semantically cohesive sections and provided with a verbose description. Some effort was made to find semantically appropriate shortcuts where possible. For instance, the keybinding for inserting a slur is ‘s’, for inserting an arpeggio, an ‘a’ is used. No search function is available within this help pane. Alternatively, the keybindings can be viewed in the local package description pageFile > Settings > Packages > <mei-friend>.. The commands can also be called using the command palette https://web.archive.org/web/20220209101922/https://atom.io/packages/command-palette. or from the toolbarPackages > MEI friend..

Conclusion and outlook

Mei‑friend can be very useful for “polishing” MEI encodings after conversion from other formats but is currently not aimed to be a full-fledged MEI editor. Display of MEI files is implemented in a user-friendly and efficient way. Speed mode – another innovation by the developers of mei‑friend – significantly improves the performance of the tool. Various code editing functionalities are implemented, mainly utilizing manipulation of ControlEvents and a few attributes. The tool is currently being redeveloped and extended as a web-browser application in the context of the project Signature Sound Vienna.

Goebl, W.; and M. Weigl, D. Alleviating the Last Mile of Encoding: The mei-friend Package for the Atom Text Editor. In Münnich, S.; and Rizo, D., editor(s), Music Encoding Conference Proceedings 2021, pages 31–39, 2022. Humanities Commons, https://music-encoding.org/conference/proceedings.html. Music Encoding Initiative. 2019. MEI Guidelines (Version 4.0.1). https://music-encoding.org/guidelines/v4/content. mei-friend package for Atom: https://atom.io/packages/mei-friend. Music Encoding Initiative. 2022. https://web.archive.org/web/20220121074651/https://music-encoding.org/about. Pugin, Laurent, Rodolfo Zitellini, and Perry Roland. 2014. “Verovio: A Library for Engraving MEI Music Notation into SVG.”. In Proceedings of the 15th International Society for Music Information Retrieval Conference, 107– 12. Taipei, Taiwan: ISMIR. https://doi.org/10.5281/zenodo.1417589. Sapp, Craig. 2017. “Verovio Humdrum Viewer”. Presented at Music Encoding Conference 2017 (MEC 2017), Tours, France. Slides available from http://bit.ly/mec2017-vhv. Tool available from http://Verovio.humdrum.org. Trompamusic, https://web.archive.org/web/20220107224134/https:/iwk.mdw.ac.at/h2020-trompa.