Some of you will already know the rm…

Some of you will already know the rm-repeated-pitches method. This finds repeating pitches in any or all voices of a slippery-chicken object and replaces them with other pitches from the current set. Of course what this is doing is ironing out some of the problems inherent to algorithmic pitch selection, and slippery chicken’s in particular.

For the Goldsmith’s project next month I’ve developed a related method called add-auxiliary-notes. This tries to deal with some of the static pitch structures that arise out of limited but extended harmonic fields. It analyses slippery-chicken voices phrase by phrase to find the most frequently used notes, then changes some of them (according to an activity-levels object) to auxiliary notes (up a semitone by default but any and varied intervals are possible). It’s already available on the SVN server so those of you who want it will find it along with documentation in the file slippery-chicken-edit.lsp after doing (update-app-src …)

If you who read facebook slippery chicken group…


If you who read facebook slippery chicken group posts you may remember this one about pedalling:

“Those of you working on piano pieces: as of yesterday, if you add one of the three pedal marks ‘ped, ‘ped-up, or ‘ped^ you’ll get the correct controller information written to your MIDI files for free—in other words, during MIDI playback the sustain pedal should work.

If you want to set the controller message of an event yourself, just e.g.
(push '(1 64 127) (midi-control-changes event))
where the first 3-element list there is (midi-channel controller-number value). 64 is the sustain pedal controller number; 127 will depress and 0 will release.

If you need this functionality do (update-app-src …)”

Just wanted to update this to mention that this will also work with the ‘uc and ‘tc marks (una corda / tre corde) and the ‘sost and ‘sost-up marks (middle / sostenuto pedal), i.e. not only will the pedal marking appear in the score but the MIDI controller data will be written when you call midi-play.

Some of you might be interested in the…

Some of you might be interested in the following bit of code to get bass notes to play louder (not at all Fletcher-Munson curve correction but that could be implemented too by using the a-weighting function).

:force-velocity can either be a fixed number or a function. If the latter then each consecutive event is passed to the function automatically by midi-play. Below we subtract the degree (equivalent to MIDI note number when using the chromatic scale) from 127 to make lower notes louder than higher notes, but we do restrict this to between 70 and 110, so there’ll be a hard cut-off—notes above MIDI 55 will have a velocity of 70 and those < 18 will have 110. Note that we do randomise/humanise the velocities by 10% for a less mechanical feeling (assuming your synth/sampler will distinguish significantly there); also that get-degree will return an average for chords.

(midi-play +jitterbug+ :force-velocity
           #'(lambda (event)
               (let* ((d (get-degree event :average t))
                      (v (when d
                             (min 110 (max 70 (- 127 d)))
                 (format t “~&~a –> ~a” d v)

I have never quite been able to separate…

I have never quite been able to separate my sadness at the loss of Luigi Nono from a feeling of greater awareness, of happiness and gratitude that he ever existed—and ever existed in our proximity. And despite the loneliness which I share with so many others who loved him, I feel, when I think of him, a unique sense of the triumph of art and a hope that its restless force will endure in times of apparent hopelessness.

Helmut Lachenmann