Generate Time Track with Nyquist or Python

Programming and Development Nyquist
1

I’m posting this in the Nyquist board because it seems to be where this functionality might live, but please move it to the scripting board if it is more appropriate.

I would like to be able to generate a “Rhythm skew” effect where I rhythmically change the tempo of audio at a particular bpm, as if it’s playing on a tape that isn’t moving at a constant speed. The easiest way I can find is to generate control points on the envelope of a time track, since this is non-destructive and I can sync it up with my track. How can I do this either with Nyquist or Python Scripting?

2

Unfortunately, time tracks are not yet available to either Nyquist or Python, other than simply creating an empty time track.

3

I see. Is there a way for me to “import” a time track that is composed of pairs of (time, value)?

4

Time tracks are currently mouse powered only. No import / export or scripting.

If you are really determined to make this work, you could manually modify the Audacity “.aup” project file (but be warned, if you make a mistake the project could become unusable).
The .aup file is XML format, and a Time track looks like this:

	<timetrack name="Time Track" isSelected="1" height="100" minimized="0" rangelower="0.900000000000" rangeupper="1.100000000000" displaylog="0" interpolatelog="1">
		<envelope numpoints="3">
			<controlpoint t="0.987261146497" val="1.000000000000"/>
			<controlpoint t="14.904458598726" val="1.078260898590"/>
			<controlpoint t="21.719745222930" val="1.015217423439"/>
		</envelope>
	</timetrack>