OpenMusic Tutorials

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Tutorial 20: Using BPFs II: Sampling a sequence

of notes

Topics

Sampling a melodic contour to produce a sequence of notes.

Key Modules Used

Chord, Chord-seq, BPF, bpf-sample, list- max

The Concept:

Here we sort of reverse the last tutorial: we take a melody, turn it into a graphic melodic contour, then use bpf-sample to take that shape and turn it back into values. When converting it back to values, we can take more or fewer samples than the original sequence, creating a “smoother” melody.

The Patch:

Enter a sequence of notes in “order” mode in the Chord and lock it:

The BPF box converts the midicents coming out of the Chord box (A) into a break-point function, a melodic contour.

The bpf-sample takes a number of ‘pictures’ of the height of the graph between the x-axis values specified at the inputs _xmin_ and _xmax_ and returns them as a list. In our example, there are 13 elements in the chord. We tell bpf-sample to sample the BPF 13 times, so the values we get back will be the same ones we put in. However, we are sampling the height of the graph. If we enter a number other than 13, we will take that many samples of the graph, and they’ll no longer line up with the original elements. This will create a new melody starting in the same place and having the same shape but with a different number of elements. Try replacing the 13 with 26.

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