Selected Topics

Complications:

• Python (I'm guessing it's python causing the problem...) doesn't understand spaces in windows filenames. The easiest fix for this is to copy the abc file, replacing the spaces with underscores ('_').
• abc2ly doesn't understand the abc method of indicating acciaccatura grace notes (the ones with the little lines through them...), which is to follow the { with a / (i.e. '{/' ). The best thing to do here is to simply delete the offending /'s! The grace notes can be fixed up properly later in the .ly file.
• Likewise, abc2ly doesn't seem to undestand what to do with expression symbols, eg. '!trill!' and '!breath!'. Just delete them (from the abc file), and add them back in later in the ly file.
• abc2ly provides the -b option, which allows us to preserve the 'beam' pattern of the abc file, instead of relying on lilypond's defaults. The problem wiht this is that abc will happily ignore 1/4 notes that are placed together (the method used to arrange beaming for 1/8th notes and smaller), abc2ly also happily transliterates the placement into beaming symbols ('[' and ']'). While Lilypond ignores incorrect beaming requests like this, when applied to 1/4 notes and longer, it complains vociferously in the log file. And while this is not a major problem, it does make finding real errors in the log file difficult. My suggestion is to rely on Lilypond's auto-beaming feature (i.e. don't use -b in abc2ly), unless it doesn't give you satisfactory results. If you do use -b, you probably will have to go in and clean up either the abc file or the .ly file to mollify the error trapping.
• whoever wrote abc2ly decided to transliterate the abc '|' symbol to '\bar "|"' in .ly . While functionally correct (abc doesn't have a notion of bar checking), this ignores the benefit of the bar checking in Lilypond. My recommendation is to do a global search and replace of the '\bar "|"' to change them to "|" .
• abc2ly generates chords in lilypond by generating 'text scripts' in the form: '^"G"'. This actually works well, in that it doesn't insert any new notes into the score. It does, however, mean that the placement of the chord symbols is subject to the note leger lines moving up and down, so the position of the chord letters is not fixed - they wander up and down, instead of being at some fixed level. Lilypond is actually quite intelligent about 'real' chords (i.e. not 'text scripts'). In 'chord mode', you can give it a series of notes, and it will extract the correct chord name for you, and even provide fret diagrams, etc. It's a lot of work, though - you have to encode each chord as a series on notes. Best to put up with the wandering letters.
• abc2ly doesn't know quite what to do with some of the abc header constructs. Actually, it's ABC that doesn't work well for me, so I have sometimes cheated... the composer command actually does work, but some of the abc utilities move it around from the top right-hand location, so in many of my abc files I have used the O: (origin) construct to indicate 'trad - FF Version'. This needs to be changed (when it occurs) in the .ly file to 'composer'.
• Other things to do in the .ly header;
• delete the 'crossRefNumber'. This is brought in by the X: command, and serves no useful purpose in Lilypond (I checked).
• any footnotes (brought in by the N: command) need to be moved to a '\markup{notes}' section (can be tacked on at the end).
• change the tagline to "the Fumblin' Fingers score version nnnnnnn - Music Engraving by Lilypond".
• include the tune's rhythm description as a 'meter = "rhythm_description"' construct.
• include the tune's 8-bar phrase structure (if available) as a 'piece = "AABBAB" construct (this puts it in the upper left corner of the page, where we expect it...)