{"id":962,"date":"2015-08-22T17:47:44","date_gmt":"2015-08-22T21:47:44","guid":{"rendered":"http:\/\/christophertrapani.com\/wordpresssite\/?page_id=962"},"modified":"2021-05-25T08:56:25","modified_gmt":"2021-05-25T12:56:25","slug":"catart-tools","status":"publish","type":"page","link":"http:\/\/christophertrapani.com\/wordpresssite\/catart-tools\/","title":{"rendered":"CataRT Tools"},"content":{"rendered":"
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CataRT TOOLS<\/span><\/strong><\/h3>\n

A nearly constant presence\u00a0in my electroacoustic work since 2012 has been CataRT<\/a>, a tool for concatenative synthesis developed by Diemo Schwarz at IRCAM.\u00a0<\/span><\/p>\n

In concatenative synthesis,\u00a0a database of prerecorded or live-recorded sound is created by\u00a0segmenting it into units, usually of the size of a note, grain, phoneme, or beat. Each grain\u00a0is analyzed for a number of sound descriptors which describe sonic characteristics, such as loudness, spectral centroid (a measure of brightness), or periodicity. These values are stored and are\u00a0recalled at the moment of synthesis, when one or more\u00a0target values is sent to the synthesis engine, and the closest unit to those given target values\u00a0(usually in the sense of minimizing a weighted Euclidean distance) is selected. The selected units are then concatenated and played, possibly after further\u00a0transformations.<\/span><\/p>\n

CataRT, available as a standalone application or a modular series of Max patches and abstractions, contains an LCD display that charts descriptors in two or more\u00a0dimensions, allowing one to visualize a descriptor space and navigate through with a mouse or other type of external controller. Introductory\u00a0videos on the\u00a0CataRT\u00a0homepage<\/a> demonstrate\u00a0the basics.<\/span><\/p>\n

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TARGETED TRANSPOSITION<\/span><\/strong><\/h3>\n

In 2011 Aaron Einbond<\/a> and I began the joint project of integrating feature modulation synthesis into\u00a0CataRT. In between the selection and synthesis stages\u2014in other words, just before the chosen grain is played back\u2014its values can be altered according to external\u00a0parameters. A basic example is loudness modulation, where an independent mixer gives levels for subsets of the corpus. Before a grain is played, its stored loudness value is recalled, then a lookup function finds the mixer coefficient to\u00a0be applied, and the resulting level is sent to CataRT in lieu of the original level.<\/span><\/p>\n

Targeted Transposition applies this same principle to pitch.\u00a0Using the bach<\/a> library developed by Andrea Agostini and Daniele Ghisi,\u00a0a \u201ctarget pitches\u201d interface has been implemented to combine with existing CataRT modules; one or more target pitches are defined before playback in this window. As grains are selected from the corpus by proximity to target descriptors, which may include pitch itself and\/or other descriptors, their note number content is examined, and a transposition value equivalent to the difference between the estimated note number and the target pitch is sent to CataRT before playback. If more than one target pitch is defined, for example a harmonic field of possible pitches, the pitch of each sample can be either drawn at random (with or without replacement) or chosen based on the shortest distance to the original pitch of the unit.<\/span><\/p>\n