Re: midi volume single note

[David Kastrup]

Gianmaria Lari <address@hidden> writes:

> On 13 November 2017 at 13:31, Caagr98 <address@hidden> wrote:
>
>> I was thinking of something like this:
>>
>> <<
>>   { c'1 }
>>   { s8 \set Voice.midiExpression=#0.5 s2.. Voice.midiExpression=#1 }
>> >> c'1
>>
>> That is, simultaneously: a) play a note, b) wait a short while, reduce
>> volume, wait until rest of the note is finished (2.. is 7/8 of a measure),
>> then reset to normal.
>>
>
> Thank you, perfect!!!!
>
> In case other people need it, here it is a complete example where c1 note
> is played reducing volume from maximum to minimum in step of 1/32.
>
> \version "2.19.80"
> right = \fixed c'' { c1 }
>
> dynamics = {
> s32 \set Voice.midiExpression=#1
> s32 \set Voice.midiExpression=#0.96774
> s32 \set Voice.midiExpression=#0.93548
> s32 \set Voice.midiExpression=#0.90323
[...]
> }
>
> \score {
>   \new Staff \with { midiInstrument = "accordion"}
>   \new Voice <<\right \dynamics>>
>   \midi {}
>   \layout {}
> }

Well, that calls for something programmatic I think.

\version "2.19.80"

right = \fixed c'' { c1 }

withExpr =
#(define-music-function (steps start end music)
   (index? number? number? ly:music?)
   (let ((len (ly:make-duration 0 0
                                (/ (ly:moment-main (ly:music-length music))
                                   (1+ steps)))))
     #{ \context Bottom
        << #music
           { #@(append
              (map
               (lambda (v)
                 #{ \set midiExpression = #v  \skip #len #})
               (iota steps start (/ (- end start) (1+ steps))))
              (list #{ \set midiExpression = #end #})) }
        >>
     #}))

\score {
  \new Staff \with { midiInstrument = "accordion"}
  \displayLilyMusic \new Voice { \withExpr 32 1 0 \right }
  \midi {}
  \layout {}
}


-- 
David Kastrup