OpenMusic Tutorials

Prev| Chapter 6. Using Musical Objects II| Next

Tutorial 17: Generation of a melodic sequence from harmonic reservoirs

Topics

Generating a melodic sequence with elements of predetermined chords.

Key Modules Used

nth-random, x-append, flat

The Concept:

We will generate a note sequence using four Chord objects as harmonic reservoirs. Each Chord contain a traditional harmonic chord structure. We will use nth-random to randomly choose notes from each reservoir, sequentially. We will concatenate (put together!) the result with x-append, preserving the harmonic order of the reservoirs (I-IV-V-I).

The Patch:

Enter the desired harmonic sequence in the Chords (A). In this example we used the tonal sequence I-IV-V-I in C major scale.

Each nth-random (B) will randomly pick a note in the Chord reservoirs.

We will ‘iterate’ (repeat) this procedure 4 times using repeat-n.

x-append (D) will concatenate these results in harmonic order (i.e first we will have 4 randomly choosen notes from the first reservoir, then 4 from the second one etc…).

In order to have this whole harmonic sequence repeat twice, we will again use the repeat-n function (E). Notice that all these iterations yield different results due to the fact that we are using nth-random function which is evaluated anew at each iteration (on the C and D levels) and therefore returns different results each time.

Try this: evaluate the output of the repeat-n at (E). You should get something like:

? OM->((6400 6700 6700 6700 7200 6000 6500 6500 5900 5900 6500 6700 6000 6000 7200 6000) (6700 6400 6700 7200 6900 7200 6000 6900 6500 5900 6500 5900 6000 6000 7200 7200))

Notice that this is a list of two lists. Plug this directly into the _lmidic_ input of the Chord-seq object. You’ll get two huge chords. This is because the list has multiple levels. When a list has other lists as its elements, we say it is nested. A tree is a nested list. When Chord-seq encounters a nested list, it assumes the sublists are chords. In order to display this as a string of ordered notes, we must ‘flatten’ the list. This is accomplished with the LISP function flat, which removes nesting. Reconnect the output of flat to the Chord-seq and evaluate.

	A note from Mikhail Malt

The old version of this patch (in a patchwork version) was a gift to Camilo Rueda when he was at Ircam as a Patchwork developper. Just in order not to break the Colombian tradition, this OM version is dedicated to Carlos Augusto Agon, another nice Colombian guy working on Computer aided composition environments.

OpenMusic