Ensemble Software: CDP

CDP SOUND TRANSFORMATION SOFTWARE

The CDP system is one of the most comprehensive and innovative sound design suites available. Largely designed by English electro-acoustic composer Trevor Wishart and reflecting his musical aesthetics in many ways, its processes cover almost every aspect of sound manipulation you've ever heard of and many that will certainly be unfamiliar, and usually from an original and compositional viewpoint.

SOUNDFILE PROCESSES
Traditional areas of sound-processing are covered very fully: for example, there are 45 filtering functions including a user-defined bank with time-variable pitch, amplitude and bandwidth. Many time-domain processes in CDP sound familiar enough, though most are more thoroughly explored than in a typical sound editor and many are unusual and distinctive. Here are some examples:

ENVELOPE
In CDP, the envelope is the the actual time-varying level, rather than a simple percentage gain control. You can extract an envelope and edit it visually or transform it in over 30 different ways, including processes like expand, invert, reverse, timestretch, invert, tremolo and shudder. You can also apply your transformed data to scores of time-varying parameters throughout the CDP system.

EXTEND and GRAIN
Segmenting and restructuring sounds is a strong feature of CDP. You can extend and re-order sounds in at least 18 different ways, exploring functions with names like Drunk, Weave, Scramble, Shred. Processes range from looped segments stepped through the sound, zig-zagging back and forth, and shredding (random segmentation).

CDP's GRAIN programs Brassage and Sausage have full-scale granular segmentation and reconstruction with pitchshift, timestretch, panning etc. and ranges of values for key parameters,. There is also a very comprehensive section for manipulating grainy sounds by reversing, repositioning, shuffling, or duplicating grains.

TEXTURE
TEXTURE is based on the algorithmic repetition of sounds. The TEXTURE suite combines random elements and user-defined constraints which can be defined rhythms, motifs, ornaments, pitch-sets or chords. The output sound may be melodic or densely packed, creating a granular texture. The Texture suite lies somewhere between a sophisticated arpeggiator and a fully-fledged algorithmic composer, and is really a program in its own right.

WAVECYCLE DISTORTION
The DISTORT suite is distinctive in operating on pseudo-wavecycles found in zero-crossings to produce a wide variety of distortions of the original.

PITCH-SYNCHRONOUS GRAINS
PSOW is an experimental grain technique for vocal sounds, allowing manipulation of formants independently of pitch, often with unexpected results.

SEQUENCERS
CDP has various sequencer programs, which are like software samplers, allowing you to realise a sequence of sounds just like a MIDI sequence, using different sound-sources. Soundshaper has a MIDI-Seqeunce facility for converting standard MIDI files to the CDP sequence format.

RETIME (new in CDP 6)
Various programs to alter the timing of silence-separated events.

MULTI-CHANNEL PROGRAMS (new in CDP 6)
Several new programs distribute sound events across multi-channel space: by shredding, iteration, zig-zagging and panning. These programs are highly distinctive in producing channel-separated variants of the original signals: you can create more channels than you need just to access the variants, which often have a hocket-like quality. In addition, there are many support programs for multi-channel work, including multi-channel mixing.

SPECTRAL PROCESSES
In the frequency domain, you can do a lot more than manipulate frequencies. Each time-slice has a loudness contour across the frequency spectrum (rather like a graphic equaliser setting). Many spectral processes transform this "spectral envelope" or other aspects of amplitude: blurring, inverting, exaggerating, stacking, holding, arpeggiating, filtering, freezing, imposing vowel-formants etc. In addition there are the more familiar processes such as vocoding (imposing the characteristics of one sound on another), morphing (making one sound change into another) and timestretching (stretching/shrinking the sound without changing pitch).

On the frequency side, two outstanding processes are TUNE, which retunes the spectrum to any desired pitches and GLIDE, which morphs the frequencies of one sound into another over any time-period. PICK allows you to extract a single pitch which may be in the sound and there are processes which stretch/shrink or shift the spectrum to create inharmonic sounds. There are new processes in CDP6 to clean sounds spectrally or SLICE the spectrum into user-defined bands, which can be distributed spatially or treated separately, for example by transposition or time domain processes such as delay or iteration. There is also an excellent new FFT based CONVOLVER: fast and easy to use.

Pitch and formants can be extracted from the spectral information, with pitch being manipulated in several ways and then combined with formant data to re-synthesize sound. For example, you can extract and quantize pitch visually within Soundshaper's GraphEd editor:

Extracted pitch quantized to exact MIDI values

INFO and DATA MANIPULATION
On the information and data manipulation side, you can view and extract from soundfiles down to sample level, including a useful spectral display, plus pseudo-soundfile displays for pitch and formants. A large proportion of parameters can be time-varying and this data can be manipulated in Soundshaper or CDP's graph editors and applied to other functions. In addition, there are around 100 functions for altering and creating tables of figures: everything from simple mathematical operations to specifically musical ones such as tempering, motivic rotation and change-ringing.

HELP
CDP is backed up by a very detailed HELP in HTML format; every parameter is carefully explained and the underlying concepts and uses for each function are also discussed. Further support is available from Trevor Wishart's book Audible Design, which places the processes he has devised in the wider context of sound composition.

SUMMARY OF KEY FEATURES

CDP SYSTEM (5.01):

Category No. of functions, including:

EDIT / MIX 69 Sample-accurate cut/paste, random cuts, masking, switching, multichannel + ambisonic support; mixfile processing; sequencers

ENVELOPE 38 Extract, reshape, replace, normalise, limit, expand, reverse, timestretch, invert

FILTER 46 Variable, hi-lo, iterated, phasing, bank, varibank [time-variable resonance], trace, suppress, gated, vowels

PITCH / FREQUENCY 20 Transpose, speed, stack, ring, cross-mod, vibrato, stretch/shift/tune spectrum

REVERB / DELAY    6 Reverb, roomverb, fixed, variable, multitap, echo

EXTEND / REORDER 22 Loop, zigzag, drunk, scramble, shred, iterate

GRAIN 16 Brassage; process grains: duplicate, envelope, remotif, repitch, shuffle, reverse, reposition, rerhythm, timewarp

TEXTURE 14 Repeat events algorithmically to create textures, with optional harmonic templates, melodic and rhythmic motifs

DISTORT-CYCLES 22 Average, omit, telescope, reverse, shuffle, pitchwarp, fractals, etc.

SPECTRAL EMPHASIZE    5 Accumulate, arpeggiate, exaggerate, focus, pluck

SPECTRAL RESHAPE    4 Average, invert, noise, spread

MORPH / FORMANTS    7 Morph, bridge, glide, vocode, cross-synthesis, get / put formants

SPECTRAL COMBINE    5 Sum, difference, interleave, maximum, mean

SPECTRAL TIME 10 Blur, drunk, shuffle, weave, expand, freeze, hold, timestretch

SPECTRAL UTILS    6 Bare, clean, cut, gain, grab, gate

PITCH PROCESSING 35 Extract pitch; approx, exaggerate, invert, randomise, shift,smooth, quantise, generate, synth, vowels; utils

SYNTH    7 Wave, noise, spectra, silence, chord, click-track

PROCESS DATA 104 Transform/generate/sort data with musical, mathematical and random functions

INFO / UTILITIES 56 File information, data conversions, view/play sound and spectral files

For further details about CDP see the Composers' Desktop Project website .