02 · CHANNEL OPERATORS
CHOP Network Explorer
Channel Operators (CHOPs) process one-dimensional time-based data streams: audio waveforms, LFO signals, sensor data, MIDI streams. CHOPs connect left-to-right, each transforming the channel data passing through its core. Audio and control signals share the same operator paradigm.
03 · AUDIO REACTIVITY
Audio-Reactive Visual Systems
Audio analysis CHOPs extract amplitude, spectrum, beat, and onset data from an audio signal. These numeric streams route to visual parameters — geometry scale, shader uniforms, material properties — creating visual systems that breathe with the music.
220 Hz
0.60
LOW
50%
04 · PROCEDURAL AUDIO
Audio Modulation Pipelines
CHOPs chain LFO, Envelope, Math, and Filter operators into modulation pipelines that drive audio synthesis parameters in realtime. Unlike fixed automation, CHOP modulation is live — tempo-synced, audio-derived, or driven by external sensors.
2.0 Hz
Sine
0.05s
0.40s
05 · OPERATOR FAMILIES
Signal Conversion Pipelines
TouchDesigner's operator families communicate through defined conversion paths. CHOP audio analysis exports to SOP geometry (wave mesh, particle systems), to MAT shader uniforms (colour, intensity), and to Texture via TOP — audio becomes light, geometry, texture.
06 · REALTIME SYNC
Ableton Link / OSC Sync
TouchDesigner integrates with Ableton Link for tempo/phase synchronisation and receives Open Sound Control (OSC) for realtime parameter control. MIDI and Ableton Link CHOPs make TD a first-class participant in any networked performance environment.
128 BPM
30 Hz
2 ms
07 · PRACTITIONERS
TD Audio Artists
Elburuz Fidan
Derivative TD · Audio Systems
Bileam Tschepe
TouchDesigner Tutorial · Elekktronaut
Paketa-Paketa
Audio-Reactive AV · Japan
Matthew Ragan
Obscura Digital · TD Pipeline
Natan Sinigaglia
Data Visualisation · AV Installation
noio (Thomas Sanchez)
TD Generative · AV Systems Design
Daito Manabe
Rhizomatiks · Realtime AV Art
Zach Lieberman
School for Poetic Computation · NYC
08 · REFERENCE
TouchDesigner Lexicon
CHOP (Channel Operator)
Operator family processing one-dimensional time-based channel data — audio waveforms, LFO signals, MIDI streams, sensor data. CHOPs are the bridge between audio analysis and visual control in TouchDesigner.
TOP (Texture Operator)
Operator family processing 2D image data — video, rendered frames, generative textures. TOPs perform compositing, colour correction, and GLSL shader operations in realtime at the GPU level.
SOP (Surface Operator)
Operator family processing 3D geometry — point clouds, meshes, particles. Audio-driven SOPs create geometry whose vertex positions, normals, or attributes respond to CHOP channels extracted from audio analysis.
MAT (Material Operator)
Operator family defining surface appearance — GLSL shaders, physically-based materials. MAT shader uniforms can be driven by CHOP audio analysis values, making visual materials respond to audio in realtime.
COMP (Component)
Self-contained sub-networks in TouchDesigner. COMPs include Geometry, Camera, Light, and Container types. Components create hierarchical project structure and can be reused across performance environments.
Audio Analysis CHOP
Built-in CHOP that analyses incoming audio and outputs derived channels: RMS level, spectrum bins, onset detection, beat detection, and per-band energy. The primary bridge between audio and visual control.
Spectrum CHOP
Performs FFT analysis on incoming audio, outputting N channels representing frequency-band energy. Resolution and window type configurable. Output channels route to any visual parameter — geometry scale, colour, particle emission.
LFO CHOP
Generates periodic waveforms (sine, triangle, square, sawtooth, random) at configurable rates. Syncs to project FPS, an external clock, or Ableton Link beat clock. The core modulation source for procedural animation.
Ableton Link CHOP
Synchronises TD's timeline to Ableton Link network session. Outputs beat position, bar position, and phase channels at sub-frame accuracy. Enables pixel-perfect beat-sync without MIDI clock jitter.
OSC In CHOP
Receives Open Sound Control messages over UDP network. Parses OSC address patterns to named channels — remote parameter control from any OSC-compatible device (phone, Ableton, Max/MSP, custom hardware).
GLSL CHOP
Custom GPU-accelerated CHOP executed as GLSL compute shader. Processes thousands of channels in parallel — particle physics, custom synthesis algorithms, signal processing operations in real GPU time.
CHOP to SOP
Conversion operator reading CHOP channels as point attribute data and injecting them into SOP geometry — amplitude → vertex Y position, frequency content → particle velocity, beat → geometry scale pulse.
Envelope CHOP
Tracks amplitude envelope of an audio signal with configurable attack, decay, sustain, and release times. Attack/release ballistics determine how quickly the envelope follows signal changes — critical for smooth visual motion.
Filter CHOP
Low-pass, high-pass, band-pass, and notch filter for CHOP channel data. Smooths noisy sensor or analysis data before routing to visual parameters — prevents jittery visual response from audio transients.
Timeline CHOP
Records and plays back CHOP channel data across the TD timeline — captured automation that can be looped, triggered, or blended with live input. Combines composed structure with live improvisation.
Beat CHOP
Beat detection from audio or external clock source. Outputs onset detection, beat confidence, and current beat/bar position. Phase can be manually nudged for beat-sync correction in live performance.
Phaser CHOP
Phases one CHOP in time relative to another — delay, advance, or offset. Used to stagger synchronized modulation across multiple channels, creating wave-like cascades in multi-element visual systems.
Math CHOP
Arithmetic operations on CHOP channels: multiply, add, clamp, remap range. Scales, inverts, and maps analysis values to target parameter ranges — bridge between raw analysis output and visual parameter space.
Python in TD
Every operator in TouchDesigner is accessible via Python scripting. Parameter values, CHOP channel reads, event callbacks, OSC parsing, and complex procedural logic can be implemented in TD's embedded Python runtime.
Realtime Performance
TD runs at fixed frame rates (30/60 fps). All processing — CHOP analysis, SOP geometry, TOP compositing — must complete within one frame budget. Performance optimisation and GPU utilisation are core TD design skills.
Perform Mode
TD's full-screen output mode, hiding the network editor. The performance window uses the full GPU budget — CHOP analysis, SOP rendering, and TOP compositing drive the output with no editor overhead.
Multi-Output
TD can drive multiple display outputs simultaneously — LED walls, projectors, DeckLink SDI outputs. Window COMPs define output regions; Output TOP operators manage signal processing for each display surface independently.