Many changes, including new names for the commands. Here is an example:
% sf2sound test '|| fundamental:261 f: tempo:120 | stacc: q do re mi fa | leg: p: h sol sol ||'
And here is the audio:
The dynamics f: and p:, for forte and piano, now work thanks to the improved back-end program quad. I have renamed it quad2samp. The command fundamental:261 sets the frequency in Hertz of do. For longer examples, you can take a file as input:
sf2sound -f theme.solfa
The file theme.solfa represents the first 15 measures of a sonatina in C by Muzio Clementi (Op. 36 No. 1). See the code pages. Here is the sound file:
Notice that those terrible popping sounds are gone. Eliminating them turned out to be a problem in waveform shaping, which is accomplished in quad2samp using some nice little quadratic functions. I will discuss these improvements and others in the next few posts, as well as give all the source code.
One of the major changes is a clearer idea of what the input language is and can do. I am dubbing the language SF — for solfa, of course. It has three basic entities: note symbols, rhythm symbols, and commands. The symbols can be accented. Thus do+ is an accented do which is interpreted as C#, while do^ is one of two ways to write C an octave above the given C, the other being do2. An important accent for a rhythm symbol is the dot. Just as in music, it increases the value by one-half. Thus q. is a dotted quarter note.
Commands may or may not take arguments. Thus we have tempo:144 but also allegro:. Some commands take more than one argument. An example is cresc:4:f, which means crescendo over four beats to forte. One can also say cresc:4, which means crescendo over four beats from the current level to whatever level results. The rapidity of the crescendo is a default constant which of course can be adjusted: crescendo-speed:1.2. The commands change the values of the “SF” machine that transforms a stream of tokens in the SF language into quadruples. So far this architecture seems to remarkably easy to extend and maintain.
This little project is more work than I bargained for, but it beats playing video games. I am having fun and learning a lot. The Audio Programming Book by Boualanger and Lazzarini is a fantastic resource.