abc 2

For discussions about the abc notation standard
Mick Pearce
Posts: 1
Joined: Sun Jun 28, 2009 6:17 pm

abc 2

Postby Mick Pearce » Sun Jun 28, 2009 7:07 pm

Some time ago I attempted to implement the proposed abc2 standard (based on the version IV draft, which I think was the last, plus Henrik Norbek's BNF version of that spec) using Prolog with the music grammar specified as DCGs. However I eventually stopped work on it. There are places in the proposal that are unclear and some just very odd. ( I haven't time to go through my notes at the moment, but eg macros are really poorly defined - as the stand they can only be used in a limited way and the %%propragate-accidentals default goes against normal music practice. And some odd things are inherited from the original abc - broken rhythms transparent to grace notes: A {c} > B is acceptable instead of the musically more obvious A > {c} B. If you're going to make a radical change to a standard, I'd clean that up (and order of elements in note groups in general)).

The BNF spec doesn't always agree with the draft and fails to put any structure onto the music elements - it roughly speaking defines a music line as a collection of things that can appear on a music line without imposing any order on them. Again by way of example, broken groups like A>B should be a syntactic unit, rather than <note> and <broken> just being something that can appear in a music line. (In part some of the problems stem from abc's mixing of line-based definitions - having to match s: and w: lines with the music lines - before you can deal with the music - you can get a better grammar if you preprocess them into the music).

If anyone's interested in going back and looking at the version 2 standard (or something in between 1.6 and 2) I'd be interested in getting involved. (I think the list died some years ago).

BTW, I don't want anything I've written above to imply that I don't like abc - I love the stuff and especially for single melodic lines it's hard to beat. I did the abc for the Yorkshire Garland project and for that I generated abc from musicxml extracted from a pdf produced by Sibelius - it's not as pretty as hand coded abc, but it was quick and accurate. And for storage of tunes it neat and compact - I implemented two versions of song browsers (one in Java, one in Prolog) for using the Digital Tradition database and stored the tunes there in abc (another conversion job I did from Songwright - I've suggested the DT changes to abc but they are reluctant!) . On the other hand, I could do without being able to arrange Beethoven in abc - I write and arrange a lot of classical guitar music and I do that in Finale or Sibelius, not abc. Just the ability to do it doesn't make it the right tool for the job!

Glad to see the site's up and hope it generates lots of interest.

Mick

Jack Campin
Posts: 9
Joined: Tue Jul 07, 2009 1:54 am
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Re: abc 2

Postby Jack Campin » Mon Aug 10, 2009 2:20 pm

some odd things are inherited from the original abc - broken rhythms transparent to grace notes: A {c} > B is acceptable instead of the musically more obvious A > {c} B. If you're going to make a radical change to a standard, I'd clean that up


It isn't broken. With music like "parlando rubato" songs, it may make much more sense to think of a gracenote as trailing after the first note in such a group.

If you were going to ban A{c}>B, which of A{c}<B and A<{c}B would you ban? How would you communicate the rationale for whatever you decided to the user?


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