(sonicArts) granular synthesis tools, cecilia and paulstretch


Outside readers will look at the title of this post and tell me, correctly, that Paulstretch isn’t a granular synthesis program. True, but we will still use it as part of our added toolbox. Paulstretch is an effect available to use in Audacity. It has only two controls: one for specifying the duration factor (5 means “5 times the original duration”), and one for specifying time resolution. Smaller time values give you better rhythmic resolution (time) but worse frequency resolution. You can experiment with this setting. If you have a very active sound (changes a lot, quickly), then try a smaller time resolution to capture that activity. For sounds that don’t change that quickly, you can use a long time resolution and better frequency resolution. You should experiment by trying medium to longer time resolutions on active sounds, and vice versa, to hear how this parameter affects the output sound.

Paulstretch uses a processing algorithm that is optimized for extreme time stretching of a sound, 8x and above, and for use on pitched input.


You can download Cecilia4 for Mac and Windows from Google Code. There is a version 5 of the software, but it does not include the Filter Warper, which is central to a lot of granular processing. Cecilia is written in Python, and looks almost identical on Mac and Windows. It can be a little clunky in some areas.

To hear audio in Cecilia, you should go to Cecilia > Preferences… and click on the speaker icon. Choose “PortAudio” for your audio driver, and whatever interface device you want to use for listening (builtin, MOTU, AudioBox, etc.). I know that I always tell you to use Core Audio on a Mac, but Cecilia is the exception.


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