Cervello

What it is. "Intelligent dance music" was a name nobody making it liked. Warp's Artificial Intelligencecompilation (1992) gave it a shelf, and Rephlex called it braindance. What the records share is a way of working more than a sound: rhythm treated as material to be cut, rolled and redrawn; melody that is wistful, detuned or out of tune on purpose; and machines asked to make choices. Cervello takes those habits one at a time and makes each one a control.

The voices. Kick, snare and an 808-style hat of six square waves; a two-operator FM voice for metal and glass (Chowning, 1973); a break slicer; a TB-303 line with slide and accent through a saturating four-pole ladder (Huovilainen, DAFx 2004); FM bells; detuned saw pads that drift like a worn tape; and a microsound voice that throws clouds of grains from whatever is playing, from the break, or from noise (Roads, Microsound, 2001), or skips like a scratched CD, as Oval made them do.

The steps. Up to 64 per track, each with its own length (polymeter) and rate, including triplets, quintuplets and septuplets (polyrhythm). Every step has velocity, probability, a ratchet of up to 16 repeats with a shape that speeds up or slows down (the drill'n'bass snare roll), microtiming of half a step either way, a note or slice, a trig condition after the Elektron machines (1:2, 3:4, fill, first…), slide, accent, reverse and a parameter lock. Eight patterns per song, and a chain to play them in order.

The generators. Each one comes from a paper or a record:

• Euclidean. Toussaint, "The Euclidean algorithm generates traditional musical rhythms" (BRIDGES, 2005)
• Indispensability. Barlow, "Two Essays on Theory" (Computer Music Journal 11/1, 1987)
• Markov chain. Ames, "The Markov process as a compositional model" (Leonardo 22/2, 1989); the evolving patterns of Autechre
• Cellular automaton. Wolfram, "Statistical mechanics of cellular automata" (Rev. Mod. Phys. 55, 1983); Miranda, "Cellular automata music" (Interface 22, 1993)
• Drill 'n' bass rolls. Aphex Twin, "Come to Daddy" (1997) and Squarepusher, "Hard Normal Daddy" (1997); Collins' SQPusher cut procedure in BBCut (ICMC 2002)
• Syncopate. Sioros & Guedes, "Complexity driven recombination of MIDI loops" (ISMIR 2011); Longuet-Higgins & Lee (1984)
• Ghost notes. Butler, "Unlocking the Groove: Rhythm, Meter, and Musical Design in Electronic Dance Music" (2006): the breakbeat's ghosted snares
• Microtiming. Frühauf, Kopiez & Platz, "Music on the timing grid" (Musicae Scientiae 17/2, 2013): microtiming as a colour, not a groove fix
• Probability field. The probabilistic step sequencing of Autechre's Max patches (Confield, 2001); Xenakis' stochastic laws
• Acid line. Roland TB-303 (1981); Aphex Twin, "Analogue Bubblebath" (1991); the slide and accent of Phuture, "Acid Tracks" (1987)
• 1/f melody. Voss & Clarke, "1/f noise in music: Music from 1/f noise" (J. Acoust. Soc. Am. 63, 1978)
• L-system. Prusinkiewicz, "Score generation with L-systems" (ICMC 1986)
• Arpeggio. Plaid, "Not for Threes" (1997); Boards of Canada, "Music Has the Right to Children" (1998)
• Chord changes. Boards of Canada, "Roygbiv" (1998): slow changes on the bar line
• Glitch scatter. Cascone, "The aesthetics of failure: post-digital tendencies in contemporary computer music" (Computer Music Journal 24/4, 2000); Oval, "94diskont" (1995)
• Odd-metre breakcore. Venetian Snares, who often sets the Amen break in seven ("Rossz Csillag Alatt Született", 2005)
• Cut: straight. The break as recorded, one slice per step
• Cut: warp. Collins, WarpCutProc1 in BBCut (2002): blocks of one, two or four slices, repeated, after the Warp Records sound
• Cut: sqpusher. Collins, SQPusher1 in BBCut (2002): straight playing broken by rolls of ever shorter repeats into the bar line, after Squarepusher
• Cut: campanology. Collins, "Generative music and laptop performance" (Contemporary Music Review 22/4, 2003): CampCut, slice order by change ringing (plain hunt)
• Cut: permute. Random permutation of eighth-note blocks: the jungle edit
• Cut: stutter. Stutters: one slice repeated at doubling speed, after Ableton Beat Repeat and BT's Stutter Edit
• Cut: breakcore. Venetian Snares and the Amen in breakcore: short blocks, reversals, rate jumps, constant rolls

Breaks. The break track plays slices of a break, either one rendered here from the drum voices or your own file, which never leaves your browser. The cut procedures (straight, warp, sqpusher, campanology, permute, stutter, breakcore) follow Nick Collins' BBCut library, which modelled breakbeat cutting as algorithms (Music Without Walls 2001; ICMC 2002). They write ordinary steps that you can edit afterwards, and with recut per bar the break is cut again live, every bar.

Time. Swing in the MPC sense; humanising jitter; and time warp, which bends the tempo with a slow wave and a drunk walk, for the rubato of Autechre's later records. Mutation lets every pattern edit itself a little at the end of each cycle: shift a hit, roll it, nudge it, change a note. Played long enough, a loop becomes a piece.

Pitch. Scales are written in cents and snapped onto the chosen tuning: 12-TET, just 5-limit, Pythagorean, quarter-tone 24-TET, 19-TET, 31-TET, Bohlen–Pierce, Carlos alpha, slendro, pelog, aged tape. Dorian in 19-TET becomes the meantone dorian; maqam rast in quarter tones keeps its neutral thirds. Over MIDI, microtones go out as pitch bend (±2 semitones). After Sethares, Tuning, Timbre, Spectrum, Scale (2005), and Carlos (1987).

Tape and grit. A bit crusher and sample-rate divider, the sound of early samplers and of failure as an aesthetic (Cascone, 2000); a tape with wow, flutter, saturation, hiss and age; a beat-repeat stutter that drops in pitch; a feedback-delay-network reverb (Jot and Chaigne, 1991); a ping-pong delay; and a glue compressor.

Presets. Each is a recipe built from the generators, so loading one twice gives two takes on the same idea:

• Drill 'n' bass, after Aphex Twin, "Come to Daddy" (1997); Squarepusher, "Feed Me Weird Things" (1996). Fast breaks cut into shrinking rolls, snare ratchets, a rubbery acid bass.
• Selected ambient, after Aphex Twin, "Selected Ambient Works 85–92" (1992). A soft four-to-the-floor under slow chords and a bell that wanders by 1/f steps.
• Hexagon sun, after Boards of Canada, "Music Has the Right to Children" (1998). A crushed hip-hop beat, swung, under detuned chords on a worn tape with an unsteady pitch.
• Gantz graf, after Autechre, "Gantz Graf" (2002) and "Confield" (2001). Polymeter (16, 13, 11, 7), FM metal, a time that warps, patterns that rewrite themselves every cycle.
• Breakcore in 7/8, after Venetian Snares, who often sets the Amen in seven ("Rossz Csillag Alatt Született", 2005). A bar of fourteen sixteenths, the break recut every bar: reversals, rate jumps, rolls.
• Not for threes, after Plaid, "Not for Threes" (1997) and "Double Figure" (2001). Bells in triplets against sixteenths, Euclidean percussion, a dotted delay.
• 94diskont, after Oval, "94diskont" (1995); Markus Popp's skipping CDs. Grains from whatever is playing, a CD that skips, soft chords, little else.
• Analogue bubblebath, after Aphex Twin, "Analogue Bubblebath" (1991); Phuture, "Acid Tracks" (1987). Four to the floor and a 303 line with slides and accents, sent into a delay.
• Hard normal daddy, after Squarepusher, "Hard Normal Daddy" (1997). Jazz-fusion bass by 1/f steps over warped breaks and snare rolls; bells on top.
• Aesthetics of failure, after Kim Cascone, "The Aesthetics of Failure" (Computer Music Journal, 2000); the clicks & cuts of Mille Plateaux. Clicks, crushed to a few bits, microtiming instead of a grid, stutters at the bar line.
• Quarter-tone acid, after Aphex Twin, "Syro" (2014), and his microtuning work for the Korg monologue (2016). Maqam rast in quarter tones: an acid line and a bell that fall between the piano keys.

Listening list. Aphex Twin, Selected Ambient Works 85–92 (1992), Richard D. James Album (1996),Drukqs (2001), Syro (2014); Autechre, Amber (1994), Tri Repetae (1995),Confield (2001); Squarepusher, Hard Normal Daddy (1997); Boards of Canada, Music Has the Right to Children (1998), Geogaddi (2002); µ-Ziq, Lunatic Harness (1997); Plaid, Not for Threes(1997); Venetian Snares, Rossz Csillag Alatt Született (2005); Oval, 94diskont (1995); The Black Dog,Bytes (1993); B12, Electro-Soma (1993); Mouse on Mars, Iaora Tahiti (1995); Funkstörung,Appetite for Disctruction (2000); Clark, Body Riddle (2006); Richard Devine, Lipswitch (2001).

Out of the browser. MIDI out on a channel per track (drums on 10 with General MIDI notes, break slices on 11 from C1), with clock; live recording to WAV; offline rendering of any number of bars or the whole chain to WAV and to a Standard MIDI File; patches as JSON. The engine runs sample by sample in an AudioWorklet and is checked inscripts/check-cervello.mts.

The stamp says PSPACE: with mutation on, whether the machine ever plays a given bar again is a reachability question over its state space, the kind of question that lives in polynomial space.