[LAU] sending random midi notes from a bash script

[Pedro Lopez-Cabanillas]

On Sunday, February 7, 2010, james morris wrote:
> On 6/2/2010, "Pedro Lopez-Cabanillas"
>
> <pedro.lopez.cabanillas at gmail.com> wrote:
> >> The tool would just be required to send a single midi note to some port.
> >> The note to be sent should be specifiable on command line, along with
> >> length/velocity ... probably would be enough.
> >>
> >> Any ideas?
> >
> >As an example, here is a bash script that can be used with cron, to play
> >hourly a tune and some strokes.
>
> Thanks Pedro, that's quite useful.
>
> I'm using the playnote function from your script. I see you make a
> translation of note names to other ascii chars using tr (before you call
> playnote), and it's this latter "scale" string I'm interested in, as
> my script does not need to deal with note names at this stage.
>
> I've used an expansion of the string "<>@ACEGHJLMOQS" to
> "<>@ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz" which does

This translation requires a bit of explanation. The first set of characters 
("cdefgabCDEFGAB") are two octaves, the lower one represented  by the 
symbols "cdefgab" and the upper one by the symbols "CDEFGAB". The two sets 
are note names used in the tune, declared at the top:

tune="C 4, E 4, D 4, g 2, C 4, D 4, E 4, C 2, \
      E 4, C 4, D 4, g 2, g 4, D 4, E 4, C 2,"

But the MIDI devices expect MIDI note numbers instead of symbolic names, so a 
translation is needed. The symbol "c" is translated into the character "<" 
(character code 0x3C, decimal 60), and the symbol "C" into the character "H" 
(code 0x48, decimal 72). The character codes are the MIDI note numbers, and 
we are writting them to character devices (/dev/midi*).

The MIDI note numbers and their corresponding musical notes can be seen in 
this nice graphic:
http://en.wikipedia.org/wiki/File:NoteNamesFrequenciesAndMidiNumbers.svg

If you don't need to deal with note names, I suggest you to use the MIDI note 
numbers directly. This gives you the widest possible range of notes.

> give me a wider range of notes, but is very middly, there's no bass
> notes nor anything from the high octaves.
>
> How might I get the bass and high end?

Another example is attached. In this case, the script plays a more complex 
tune for two voices codified without using symbolic note names. Using this 
technique you can even specify different velocities for each note (although 
this example uses 0x64, dec.100 for all notes). The sample also uses running 
status and knows how to cope with silences.

Regards,
Pedro
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