Re: A few questions

[Juergen Reuter]

Hi, Elie!

Sorry for the late answer!

On Thu, 29 Dec 2005, Elie Roux wrote:

> One of the aim will certaily be to make a standard for gregorian chant 
> representation, that will be under GPL, and that everyone will be able to 
> use, a bit like MusicXML is ; I think it is quite important that something 
> like that exists. But of course it's just a part of the project, other parts 
> will be how to write it simply (eventually with a GUI like denemo) and how to 
> print it.

I guess you had a look at the "Ancient notation" and, in particular, the 
"Gregorian square neumes ligatures" section in the lilypond manual 
(section 7.7.10.2 as of lily 2.7.26)?  Lily comes with a low-level input 
language (e.g. the "high-level" ligature torculus is expressed as a 
combination of "low-level" ligatures pes and flexa).  But nevertheless,
this language still abstracts from a particular flavour of notation 
(i.e. the language does not express the graphical appearance of the 
neumes, but is musicologically common for square neumes, gothic numes, 
adiastematic neumes, etc.; although, currently only square neume ligatures 
are fully implemented).

> I explored some pists for printing : MusiXTeX seems interesting but it is not 
> complete for gregorian chant. One part of the project could consist in 
> completing it. I also watched OpusTeX, but even if it seems better-made, the 
> licence is not clear, and I want to make something totally under GPL.

While the input language for Lily's Gregorian Chant implementation 
has been developed from scratch, OpusTeX served as a model with respect to 
the features supported.  Only very few of OpusTeX's features are still 
missing, most notably the versus/responsio marks and horizontal alignment 
of vowels in the lyrics with left side of corresponding ligatures. 
OpusTeX's \augmentumduplex command is considered superfluous for Lily, 
providing that the horizontal placement of dots within ligatures will be 
fixed.  \musicinitial and \textinitial are also missing, but can be 
mimicked with help of the instrument name engraver (though we may want to 
add handy scheme macros for this purpose).  Lily has also severe problems 
with spacing between ligatures, and placement of accidentals within 
ligatures is not yet handled correctly.  Meanwhile, I consider Lily's 
Gregorian Chant engine much better than OpusTeX with respect to many 
typographical details (except for horizontal alignment).

> But writing MusiXTeX or OpusTeX is totally horrible, with key words like 
> "\punctumreversumparvum", so another way to write it must be used. Lilypond 
> style of writing seems apreciated, that's why I'm interested in defining some 
> grammar for gregorian chant in the style of Lilypond, and eventually 
> integrate it into Lilypond for another way of printing.

Can you explain this in more detail?  Is your plan to extend or replace 
the current input language for Gregorian Chant notation?

> But a first step 
> could be a definition of an easy language, that could be converted into xml, 
> and from xml to MusiXTeX for example, even if it is unwise :).

Conversion from a (musicological oriented) xml language to MusiXTeX should 
be basically feasible, but will probably be a lot of work to implement, 
since MusiXTeX's input language is rather CAD-stylish than musicologically 
oriented.

> This language 
> could of course evolve as the printing system (of Lilypond) would evolve too, 
> but evolution is not dangerous, as all partitions could be converted in xml, 
> that will not evolve.
>
> I'm very interested in the evolution and the actual state of Lilypond's 
> gregorian chant engine, it would be nice if I could have informations, and, 
> if the project goes in this direction, I could collaborate. I think producing 
> notation is important, but I don't know how Lilypond produces it, is it 
> metafont ?

There are a couple of Gregorian Chant characters implemented in metafont, 
see appendix C.4 in the tutorial:
http://lilypond.org/doc/v2.7/Documentation/user/lilypond/The-Feta-font.html

(Search in this table for characters that contain the 
substring "vaticana" in their name.)

More "dynamic" shapes, such as the curved shape of the porrectus, are 
drawn "on the fly" by directly generating proper postscript/pdf code.

> Thank you,

Hope that helps,
Juergen