Channel nodes create, filter, and manipulate channel data.
Nodes
 | Acoustic | Design audio filters and sound materials for the spatial audio system. |
 | Area | Calculates the area under a channel’s graph, which is the same as calculating the “integral” of a channel, or “integrating” the channel. |
 | Attribute | Adds, removes or updates attributes of the input chop. |
 | Audio In | Receives audio input from the analog audio ports or the digital port. |
 | Band EQ | A 14-band equalizer which filters audio input channels in the same way that a conventional band equalizer uses a bank of sliders to filter fixed-frequency bands of sound. |
 | Beat | Manually tap the beat of a piece of music, and automatically generate a repeating ramp or pulse that continues to keep time with the music after the taps stop. |
 | Blend | Combines two or more chops in input 2, 3 and so on, by using a set of blending channels in input 1. |
 | BlendPose | Performs multi-dimensional, example-based interpolation of channels. |
 | Channel | Creates channels from the value of its parameters. |
 | Composite | Layers (blends) the channels of one CHOP on the channels of another CHOP. |
 | Constant | Create up to forty new channels. |
 | Copy | Produces multiple copies of the second input along the timeline of the first input. |
 | Count | Counts the number of times a channel crosses a trigger or release threshold. |
 | Cycle | Creates cycles. |
 | Delay | Delays the input, and can be run in normal or time-sliced mode. |
 | Delete | Removes channels coming from its input. |
 | Dynamics | Extracts any information from a DOP simulation that is accessible through the dopfield expression function. |
 | Envelope | Outputs the maximum amplitude in the vicinity of each sample of the input. |
 | Export | A convenient tool for exporting channels. |
 | Expression | Modify input channels by using expressions. |
 | Extend | Only sets the “extend conditions” of a chop, which determines what values you get when sampling the CHOP before or after its interval. |
 | Fan | Used for controlling other CHOPs. |
 | Feedback | Get the state of a chop as it was one frame or time slice ago. |
 | Fetch | Imports channels from other OPs. |
 | File | Reads in channel and audio files for use by chops. |
 | Filter | Smooths or sharpens the input channels. |
 | For | Internal node used by the Foreach CHOP |
 | Foreach | Divides the input channels into groups, cooking the contained network for each group. |
 | Function | Provides more complicated math functions than found in the Math CHOP: trigonometic functions, logarithmic functions and exponential functions. |
 | Geometry | Uses a geometry object to choose a sop from which the channels will be created. |
 | Gesture | |
 | Handle | The “engine” which drives Inverse Kinematic solutions using the Handle object. |
| Hold | Sample and hold the value of the first input. |
 | IKSolver | Solves inverse kinematics rotations for bone chains. |
 | Image | Converts rows and/or columns of pixels in an image to CHOP channels. |
 | Interpolate | Treats its multiple-inputs as keyframes and interpolates between them. |
| InverseKin | Generates channels for bone objects based on a bone chain and an end affector. |
 | Jiggle | Creates a jiggling effect in the translate channels passed in. |
 | Keyboard | Turns key presses into channel output. |
 | Lag | Adds lag and overshoot to channels. |
 | Limit | Provides a variety of functions to limit and quantize the input channels. |
 | Logic | Converts channels of all its input chops into binary channels and combines them using a... |
 | Lookup | Uses a channel in the first input to index into a lookup table in the second input, and output values from the lookup table. |
 | MIDI In | The MIDI In CHOP reads Note events, Controller events, Program Change events, and Timing events from both midi devices and files. |
 | MIDI Out | The MIDI Out CHOP sends MIDI events to any available MIDI devices. |
 | Math | Perform a variety of arithmetic operations on and between channels. |
 | Merge | Takes multiple inputs and merges them into the output. |
 | Mouse | Outputs X and Y screen values for the mouse device. |
 | Network | Similar to the Pipe In/Out CHOPs in Network mode. |
 | Noise | Makes an irregular wave that never repeats, with values approximately in the range -1 to +1. |
 | Null | Used a place-holder and does not have a function of its own. |
 | Object | Compares two objects and returns information on their relative positions and orientations. |
| ObjectChain | Creates channels representing the transforms for a chain of objects. |
 | Oscillator | Generates sounds in two ways. |
 | Parametric EQ | Filters an audio clip, and then applies other audio effects. |
 | Particle | Produces translate and rotate channels to move Objects according to the positions of particles in a POP Network. |
 | Pass Filter | Filters audio input using one of four different filter types. |
 | Phoneme | Translates english text into a series of phonetic values. |
 | Pipe In | Pipes data from custom devices into a CHOP, without needing the Houdini Developers' Kit or knowledge of Houdini internals. |
 | Pipe Out | Transmit data out of Houdini to other processes. |
 | Pitch | Attempts to extract the fundamental pitch of a musical tone from the input audio. |
 | Pretransform | Takes translate, rotate, and/or scale channels and transforms them using the pretransform of the given object. |
 | Pulse | Generates pulses at regular intervals of one channel. |
 | Puppet | Interface to a variety of PuppetWorks devices through a serial port connection. |
 | Record | |
 | Rename | Renames channels. |
 | Reorder | Reorders the first input CHOP’s channels by numeric or alphabetic patterns. |
 | Resample | Resamples an input’s channels to a new rate and/or start/end interval. |
 | Sequence | Takes all its inputs and appends one chop after another. |
 | Shift | This time-shifts a CHOP, changing the start and end of the CHOP’s interval. |
 | Shuffle | Reorganizes a list of channels. |
 | Slope | Calculates the slope (or derivative) of the input channels. |
 | Spatial Audio | The rendering engine for producing 3D audio. |
 | Spectrum | Calculates the frequency spectrum of the input channels, or a portion of the channels. |
 | Spline | Edit the channel data by using direct manipulation of cubic or Bezier handles in the graph of the CHOP. |
 | Spring | Creates vibrations influenced by the input channels, as if a mass was attached to a spring. |
 | Stretch | Preserves the shape of channels and the sampling rate, but resamples the channels into a new interval. |
 | Subnetwork | Allows for the simplification of complex networks by collapsing several CHOPs into one. |
 | Switch | Control the flow of channels through a CHOPnet. |
 | Transform | Takes translate, rotate, and/or scale channels and transforms them. |
| TransformChain | Combines a chain of translate, rotate, and/or scale channels. |
 | Trigger | Adds an audio-style attack/decay/sustain/release (ADSR) envelope to all trigger points in the input channels. |
 | Trim | Shortens or lengthens the input’s channels. |
 | VEX CHOP | References a VEX program that can manipulate channel data. |
 | VEX Waveform | This function is a sub-set of the waveform CHOP. |
 | VOP CHOP | Contains a VOP network that can manipulate channel data. |
 | Vector | Performs vector operations on a set or sets of channels. |
 | Voice Split | The Voice Split CHOP takes an audio track and separates “words” out into different channels. |
 | Voice Sync | The Voice Sync CHOP detects phonemes in an audio channel given some audio phoneme samples and pro... |
 | Warp | Time-warps the channels of the first input (the Pre-Warp Channels) using one warping channel in the second input. |
 | Wave | Creates a waveform that is repeated. |