Re: [Denemo-devel] MIDI events for shortcuts

[Richard Shann]

On Tue, 2014-09-30 at 23:05 +0200, Andreas Schneider wrote:
> I see, thank you. Now that I know how it works, I can see the MIDI
> messages. I can translate the numbers to hexadecimal with a calculator.
> But with my sparse scheme skills, one large number is not easy to handle
> . You offered to extend d-GetMidi to return a list of bytes. That would
> make things much easier (though I need to learn how to handle several
> return values).
OK, I have done that: (d-GetMidi #f) now returns a list of four numbers.
for example

(list-ref (d-GetMidi #f) 0)

returns 144 for the note on and 128 for the note off. It would have a
channel number included as well, but this is 0 on my controller.

(list-ref (d-GetMidi #f) 2) returns the velocity

Of course you would assign (d-GetMidi #f) first

(set! midi (d-GetMidi #f))

otherwise each call would get a different midi event.

> 
> I will try to write some scheme filter next weekend, using AngryDelete
ok - there is a call to d-SetMidiCapture in that code, which I don't
remember the details of, but I see that it is to do with the situation
where you have more than one score open at once. Other than that the
code doesn't look too terrible, though I wouldn't use the verbose lambda
form nowadays, (let loop () ... is much neater.

> as a template. In this context, I have another question: What is the
> scheme command to toggle the link to the MIDI keyboard (what the caps
> lock key does)?
there isn't one - I'm not sure why.
>  Will it work to use it, as I don't know if the message
> to turn the link back on will be received? Maybe it is better to
> implement the keyboard link functionality in the scheme filter directly,
> i.e. set a variable whether to evaluate the MIDI messages or not (and
> wait for the "turn the link back on" message).

if you want to switch to hearing the notes set a switch to cause playing
the note received in response to receiving one in the loop getting MIDI
events. (Besides d-PutMidi, which needs the midi bytes, there are actual
commands to play a note passing the note number, velocity, channel etc).

HTH

Richard