Call for Help: BMC -- Braille Music Compiler

Since 2009, I am persuing a personal programming project. As I am not a professional programmer, I have spent quite a lot of that time exploring options. I have thrown out about three or four prototype implementations already. My last implementation seems to contain enough accumulated wisdom to be actually useful. I am far from finished, but the path I am walking now seems relatively sound.

So, what is this project about? I have set myself a rather ambitious goal: I am trying to implement a two-way bridge between visual music notation and braille music code. It is called BMC (Braille Music Compiler).

My problem: I am, as some of you might remember, 100% blind. So I am trying to write a translator between something I will never see directly, and its counterpart representation in a tactile encoding I had to learn from scratch to be able to work on this project. Braille music code is probably the most cryptic thing I have ever tried to learn. It basically is a method to represent a 2-dimensional structure like staff-notation as a stream of characters encoded in 6-dot braille.

As the goal above states, I am ultimately trying to implement a converter that works both ways. One of my prototypes already implemented reading digital staff notation (MusicXML) and transcribing it to Braille. However, to be able to actually understand all the concepts involved, I ended up starting from the other end of the spectrum with my new implementation: parsing braille music code and emitting digital staff notation (LilyPond and MusicXML). This is a rather unique feature, since while there is commercial (and very expensive) software out there to convert MusicXML to braille music code, there is, as far as I know, no system that allows to input un-annotated braille music code and have it automatically converted to sighted music notation.

So the current state of things is, that we are able to read certain braille music code formats, and output either reformatted (to new line-width) braille music code, LilyPond or MusicXML.

The ultimate goal is to also implement a MusicXML reader, and convert the data to something that can be output as braille music code.

While the initial description might not sound very hard, there are a lot of complications arising from how braille music code works, which make this quite a programming challenge. For one, braille music note and rest values are ambigious. A braille music note or rest that looks like a whole can mean a whole or 16th. A braille music note or rest that looks like a half can mean a half or a 32nd. And so on. So each braille music code value can have two meanings. The actual value can be caluclated with a recursive algorithm that I have worked out from scratch over the years. The original implementation was inspired by Samuel Thibault (thanks!) and has since then evolved into something that does what we need, while trying to do that very fast. Most input documents can be processed in almost no time, however, time signatures with a value > 1 (such as 12/8) tend to make the number of possible choices exploed quite heavily. I have found so far one piece from J.S. Bach (BWV988 Variation 3) which takes about 1.5s on my 3GHz AMD (and the code is already using several CPU cores).

Additionally, braille music code supports a form of "micro"-repetitions which are not present in visual staff notation which effectively allow certain musical patterns to be compressed if represented in braille.

Another algorithmically interesting part of BMC that I have started to taclke just recently is the linebreaking problem. Braille music code has some peculiar rules when it comes to breaking a measure of musical material into several lines. I ended up adapting Donald E. Knuth's algorithm from Breaking Paragraphs into Lines for fixed-width text. In other words, I am ignoring the stretch/shrink factors, while making use of different penalty values to find the perfect solution for the problem of breaking a paragraph of braille music code into several lines.

One thing that I have learnt from my perivous prototype (which was apparently useful enough to already acquire some users) is that it is not enough to just transcribe one format to another. I ultimately want to store meta information about the braille that is presented to the user such that I can implement interactive querying and editing features. Braille music code is complicated, and one of the original motivations to work on software to deal with it was to ease the learning curve. A user of BMC should be able to ask the system for a description of a character at a certain position. The user interface (not implemented yet) should allow to play a certain note interactively, or play the measure under the cursor, or play the whole document, and if possible, have the cursor scroll along while playback plays notes. These features are not implemented in BMC yet, but they have been impleemnted in the previous prototype and their usefulness is apparent. Also, when viewing a MusicXML document in braille music code, certain non-structural changes like adding/removing fingering annotations should be possible while preserving unhandled features of the original MusicXML document. This also has been implemented in the previous prototype, and is a goal for BMC.

I need your help

The reason why I am explaining all of this here is that I need your help for this project to succeed. Helping the blind to more easily work with traditional music notation is a worthwhile goal to persue. There is no free system around that really tries to adhere to the braille music code standard, and aims to cover converting both ways. I have reached a level of conformance that surpasses every implementation of the same problem that I have seen so far on the net.

However, the primary audience of this software is going to be using Windows. We desperately need a port to that OS, and a user interface resembling NotePad with a lot fewer menu entires. We also need a GTK interface that does the same thing on Linux. wxWindows is unfortunately out of question, since it does not provide the same level of Accessibility on all the platforms it supports. Ideally, we'd also have a Cocoa interface for OS X. I am afraid there is no platform independent GUI framework that offers the same level of Accessibility on all supported platforms. And since much of our audience is going to rely on working Accessibility, it looks like we need to implement three user interfaces to achieve this goal :-(.

I also desperately need code reviews and inspiration from fellow programmers. BMC is a C++11 project heavily making use of Boost. If you are into one of these things, please give it a whirl, and emit pull requests, no matter how small they are. While I have learnt a lot in the last years, I am sure there are many places that could use some fresh winds of thought by people that are not me. I am suffering from what I call "the lone coder syndrome".

I also need (technical) writers to help me complete the pieces of documentation that are already lying around. I have started to write a braille music tutorial based on the underlying capabilities of BMC. In other words, the tutorial includes examples which are being typeset in braille and staff notation, using LilyPond as a rendering engine. However, something like a user manual is missing, basically, because the user interface is missing. BMC is currently "just" a command-line tool (well enough for me) that transcribes input files to STDOUT. This is very good for testing the backend, which is all that has been important to me in the last years. However, BMC has reached a stage now where its functionality is likely useful enough to be exposed to users. While I try to improve things steadily as I can, I realize that I really need to put out this call for help to make any useful progress in a foreseeable time.

If you think it is a worthwhile goal to help the blind to more easily work with music notation, and also enable communication between blind and sighted musicians in both ways, please take the time and consider how you could help this project to advance. My email address can be found on my GitHub page. Oh, and while you are over at GitHub, make sure to star BMC if you think it is a nice project.

It would be nice if we could produce a end-user oriented release before the end of this year.



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