Saturday, 17 April 2010

The OpenMusic OMalea library - Random Walk

In our last post we had a look at some of the functions in the omalea OpenMusic library.

In the last post we looked at mapping some different probability distributions to pitch. Using other omalea functions, we can explore a number of random walk functions to generate pitch sequences:

Random walks
Imagine a drunk walking home. When he reaches a junction he can turn left, right or carry straight on, being quite drunk he randomly chooses a direction, then he reaches another junction and repeats the process.

Using a random walk process for deciding pitches with algorithmic composition, we choose a start note and then randomly choose between the same note, a note above or a note below, we can usually choose how big a steps our 'drunk' can take.

These two random walks brownian1 and randwalk1 set a start point, upper and lower boundaries, a sequence length and a bandwidth or maximum step.

brownian1:

rand-walk1:

The layout of both examples if fairly straightforward with the random walk function and a rhythm-tree, feeding into a voice object.

In a future post we'll look at some of the remaining omalea functions, including using markov chains in OpenMusic.

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