MetaSounds Reference Guide in Unreal Engine | Unreal Engine 5.0 Documentation

The MetaSound Editor is where MetaSounds are created, modified, and previewed. The MetaSound Graph, contained within the MetaSound Editor, is composed of a variety of pins and nodes which make up the design of every MetaSound.

The MetaSound Graph functions a bit differently than the graph found in Blueprints. In Blueprints, the graph functions as an execution graph, while in MetaSounds, the graph functions as a flow graph.

The pin and node types listed in this document are built-in types, but you can add your own types by using the C++ API.

Pin Types

MetaSound nodes interact with a variety of data types through pin connections, both individual (circle connector) and array (block connector).

Pin Type	Description
Trigger	Comparable to modular synthesis triggers and are used to execute other nodes, similar to execution pins in Blueprints. They can be connected to multiple (or even zero) other nodes at once.
Audio	Represent an actual audio buffer that can be manipulated by MetaSound nodes. In some instances, these pins may be parameters intended to be consumed at audio-rate, such as for frequency modulation synthesis.
Time	Represent a time value. In most cases, they use seconds as their default time unit in the MetaSound Editor.
String	Provide labeling and debugging functionality. These pins are not directly used during playback, but are useful for relaying information to the audio designer, such as outputting node information to the console log.
UObject	Represent a supported UObject type, such as USoundWave which is commonly used to provide the Wave Player node with a reference to the asset to be played.
Bool	Represent a boolean variable.
Float	Represent a floating-point number variable.
Int32	Represent an integer (4 bytes) variable.
Enum	Represent an enumerated variable.

When Trigger nodes are triggered through timing nodes or through gameplay events, they are sample-accurate and will execute on a precise sample index in the audio rendering block. However, since other node types do not operate at audio rate, a Trigger input may generate a block rate output if it is connected to another node type.

Input and Output Nodes

Input Nodes Output Nodes

Input and Output nodes provide access to pins that typically begin or end a data flow through a MetaSound. For example, every MetaSound starts with an On Play Input node and an On Finished Output node. The On Play Input node has a Trigger pin output used to signal other nodes to begin when the MetaSound plays, and the On Finished Output node has a Trigger pin input used to receive a signal when the MetaSound finishes playing.

Additional Inputs and Outputs can be created in the Members panel of the MetaSound Editor. Afterwards, the desired properties, such as Display Name and Type, can be set in the Details panel. Next, you can create a new node instance by right-clicking an empty space in the graph and selecting the corresponding Get Input or Set Output node option from the context menu. You can also drag the Input or Output from the Members panel into the graph to create the new Input node instance.

Variable Nodes

You can use Variable nodes to access and manipulate variables that support Function nodes in your MetaSound. Three node types exist for each individual variable in your asset: Get Variable, Get Delayed Variable, and Set Variable. Get Variable and Set Variable provide immediate read or write access to the associated variable, whereas Get Delayed Variable delays the read by a block and can be used to mitigate cycles.

Like Inputs and Outputs, Variables can be created in the Members panel of the MetaSound Editor and their properties set in the Details panel. You can create Variable node instances using the right-click context menu in the graph, but only the Get Variable node can be created by dragging from the Members panel.

MetaSound Variables cannot be accessed by Blueprints.

Conversion Nodes

Conversion nodes change one pin type into another supported pin type, similar to Blueprint conversion nodes.

Supported Conversions

From	To
Audio	Float
Bool	Float or Int32
Float	Audio, Bool, Int32, or Time
Frequency Multiplier	Semitone
Int32	Bool, Float, Time, or Enum
Semitone	Frequency Multiplier
String	Transmission:Address
Time	Float or Int32
Enum	Int32

Graph Nodes

Graph nodes allow for composition capability as they provide an access point to the graphs of other MetaSounds in your project. These nodes have connection pins based on the Inputs and Outputs of another MetaSound, so you can use them to influence the design of the MetaSound containing it.

Function Nodes

Function nodes come in a large variety of types and provide the functionality required to play audio files, mix sounds, apply filters and effects, and more.

General

Additive Synth

The Additive Synth node synthesizes audio by adding given sinusoids together.

Additive Synth Inputs

Input	Description
Base Frequency	The sinusoid frequency the harmonics are based on. The value is clamped from 0.0 to the Nyquist frequency.
HarmonicMultipliers	An array of harmonic multipliers applied to the base frequency. The number of sinusoids used depends on the size of this array. The values are clamped from 0.0 to a maximum so the resulting frequency won't go above the Nyquist frequency.
Amplitudes	The array of sinusoid amplitudes. The values are clamped to a range of 0.0 to 1.0
Phases	The array of sinusoid phases (in degrees). The values are clamped to a range of 0.0 to 360.
Pan Amounts	The array of pan amounts (using equal power law). For example, a value of -1.0 is fully left and a value of 1.0 is fully right.

Additive Synth Outputs

Output	Description
Out Left / Right Audio	The synthesized audio output (left / right channels).

BPM To Seconds

The BPM To Seconds node calculates a beat time in seconds from the given beats per minute (BPM), beat multiplier, and divisions of a whole note.

BPM To Seconds Inputs

Input	Description
BPM	The input target BPM.
Beat Multiplier	The multiplier value to apply to the BPM.
Division of Whole Note	The divisions of a whole note.

BPM To Seconds Outputs

Output	Description
Seconds	The output beat time in seconds.

Envelope Follower

The Envelope Follower node outputs an envelope from an input audio signal.

Envelope Follower Inputs

Input	Description
In	The input audio signal.
Attack Time	The attack time (in seconds).
Release Time	The release time (in seconds).
Peak Mode	The following-method of the envelope follower: MS: Envelope follows a running Mean Squared of the audio signal. RMS: Envelope follows a running Root Meat Squared of the audio signal. Peak: Envelope follows the peaks in the audio signal.

Envelope Follower Outputs

Output	Description
Envelope	The output envelope value (block rate).
Audio Envelope	The output envelope value (audio rate).

Flanger

The Flanger node applies a flanger effect to the input audio.

Flanger Inputs

Input	Description
In Audio	The input audio signal to apply the flanger effect to.
Modulation Rate	The Low-Frequency Oscillator (LFO) rate that varies the delay time (in Hz). This value is clamped at block rate.
Modulation Depth	The LFO amplitude (strength) that scales the delay time.
Center Delay	The center delay amount (in milliseconds).
Mix Level	The balance between original and delayed signal. The value should be between 0 and 1.0. For example, a value of 0.5 uses equal amounts of each signal and a value greater than 0.5 uses more delayed signal than non-delayed signal.

Flanger Outputs

Output	Description
Out Audio	The output audio signal with the flanger effect applied.

Get Wave Duration

The Get Wave Duration node returns the duration of an input Wave asset (in seconds).

Get Wave Duration Inputs

Input	Description
Wave	The Wave asset to get the duration of (in seconds).

Get Wave Duration Outputs

Output	Description
Duration	The duration of the Wave asset (in seconds).

InterpTo

The InterpTo node interpolates between the current value and a target value over a specified time.

InterpTo Inputs

Input	Description
Interp Time	The time to interpolate from the current value to the target value.
Target	The value to interpolate to.

InterpTo Outputs

Output	Description
Value	The current value.

Wave Player

The Wave Player node is used to play a Wave asset.

Wave Player Inputs

Input	Description
Play / Stop	The Play and Stop triggers start and stop the Wave Player playback at a sample-accurate moment in time.
Wave Asset	The Wave asset played by the Wave Player during playback. This asset uses the same real-time decoders as all other sound sources in Unreal Engine.
Start Time	The time within the Wave asset to begin playing the audio file. This is also referred to as seek time.
Pitch Shift	The Pitch Shift to use for the Wave Player. This is defined in units of semitones to account for the non-linear nature of frequency scaling.
Loop	Whether the Wave Player will loop the audio file or stop when it's finished. This can be toggled at any time during playback from the graph.
Loop Start	The Loop Start indicates at which point in time the Wave Player will loop the audio file.
Loop Duration	The Loop Duration represents the total time the loop will play. Any value other than -1 sets the end point of the loop to the sum of the Loop Start and Loop Duration values, while a value of -1 loops the entire audio file.

Wave Player Outputs

Output	Description
On Play	Triggers when the Wave Player's Input Play pin is triggered.
On Finished	Triggers when the Wave Player finishes playing the audio file. This pin will trigger on the same sample point where the audio file finishes playing.
On Nearly Finished	Triggers on the audio rendering block before the audio file is expected to finish playback. This is commonly used to loop back and pick a new audio file variation for the Wave Player.
On Looped	Triggers on the sample where a sound looped based on the looping settings.
On Cue Point	Triggers when a cue point has been parsed in the Wave Player. Cue points are metadata embedded in audio wave files on import. Cue points are often used by sound designers to trigger events or loop points in their audio at exact points in time. With this feature, sound designers can procedurally trigger MetaSound behavior based on embedded data in the imported audio wave file. This pin is executed with sample accuracy, but the integer and label associated with the cue point is read at the block rate. Cue points in the audio wave file that are closer together than the block rate of the MetaSound will only trigger on the last cue point in that block.
Cue Point ID	The ID of the cue point as parsed from the imported audio wave file.
Cue Point Label	The label of the cue point as parsed from the imported audio wave file.
Loop Percent	The current location in the audio wave file within the given loop region.
Playback Location	The current location in the audio wave file as a fraction of the total length of the audio wave file.
Out Left / Right	The left and right channel audio of a stereo audio file. In the case of mono file playback, the audio in the right and left channels are up-mixed using mono-channel duplication.

WaveShaper

The WaveShaper node applies a non-linear shaping to the input audio signal.

WaveShaper Inputs

Input	Description
In	The input audio signal to apply the non-linear shaping to.
Amount	The amount of the non-linear wave shaping to apply.
Bias	The DC offset to apply before wave shaping.
OutputGain	The amount of gain to apply after processing.
Type	The type of algorithm to use to process the audio.

WaveShaper Outputs

Output	Description
Out	The output audio signal with the non-linear shaping applied.

Array

Array functions provide options to manipulate arrays within a MetaSound. Each of these functions have different versions which allows them to support arrays of several common data types, including: Bool, Float, Int32, String, Time, Transmission:Address, and WaveAsset.

Concatenate

The Concatenate node concatenates two arrays on a given trigger.

Concatenate Inputs

Input	Description
Trigger	The trigger on which to concatenate the input arrays.
Left / Right Array	The input arrays.

Concatenate Outputs

Output	Description
Array	The concatenated array.

Get

The Get node retrieves an element from an array at the given index.

Get Inputs

Input	Description
Trigger	The trigger on which to retrieve the specified array element.
Array	The array from which to retrieve an element.
Index	The index of the element to retrieve.

Get Outputs

Output	Description
Element	The value of the retrieved element.

Num

The Num node returns the number of elements in the given array.

Num Inputs

Input	Description
Array	The array whose elements will be counted.

Num Outputs

Output	Description
Num	The number of elements in the given array.

Random Get

The Random Get node randomly retrieves elements from an input array. Optionally, an array of weights can be supplied to adjust the randomness.

Random Get Inputs

Input	Description
Next	The trigger on which to get the next random value in the array.
Reset	The trigger on which to reset the randomization seed for the array.
In Array	The input array from which to randomly retrieve elements.
Weights	(Optional) An input array of weights used to define the probability of each entry retrieved. If not provided, an even probability for all elements is assumed. If this array is shorter than the input array, it is repeated to match the size.
Seed	The seed used for the random shuffle. The default value of -1 will use the current time.
No Repeats	The number of elements to track to avoid repeating in a row. For example, a value of 2 prevents this node from repeating the last two selected elements.
Enabled Shared State	If enabled, this node's state is shared across instances of this MetaSound to avoid playing the same exact variations at the same time.

Random Get Outputs

Output	Description
On Next	Triggers when the Next input is triggered.
On Reset	Triggers when the Shuffle input is triggered or if the array is auto-shuffled.
Value	The randomly-selected value from the input array.

Set

The Set node sets the value of a specified index in a given array.

Set Inputs

Input	Description
Trigger	The trigger on which to set value in the array.
Array	The array in which a value will be set.
Index	The index to set in the target array.
Value	The value to which the selected index is set.

Set Outputs

Output	Description
Array	The array after the setting operation is completed.

Shuffle

The Shuffle node outputs elements from a shuffled array.

Shuffle Inputs

Input	Description
Next	The trigger on which to get the next value in the shuffled array.
Shuffle	The trigger on which to shuffle the array manually.
Reset Seed	The trigger on which to reset the random seed stream.
In Array	The array from which to shuffle and output elements.
Seed	The seed used for the random shuffle. The default value of -1 uses the current time.
Auto Shuffle	If enabled, automatically shuffles when the array has been read completely.
Enabled Shared State	If enabled, the state is shared across instances of this MetaSound.

Shuffle Outputs

Output	Description
On Next	Triggers when the Next input is triggered.
On Shuffle	Triggers when the Shuffle input is triggered or if the array is auto-shuffled.
On Reset Seed	Triggers when the Reset Seed input is triggered.
Value	The value of the currently-selected element.

Subset

The Subset node returns a subset of an input array.

Subset Inputs

Input	Description
Trigger	The trigger on which to generate a subset.
Array	The input array from which to get a subset.
Start / End Index	The first and last indices to include in the subset.

Subset Outputs

Output	Description
Array	The subset of the input array.

Debug

Print Log

The Print Log node is used to record values to the Output Log on a given trigger for debugging purposes. There are multiple versions of this node in order to support several common data types, including: Bool, Float, Int32, and String.

Print Log Inputs

Input	Description
Trigger	The trigger on which to write the set value to the log.
Label	The label to attach to the value logged.
Value To Log	The value to record to the log when triggered.

Delays

Delay

The Delay node provides a mono buffer delay that supports dry level, wet level, and feedback. For multi-channel buffer delay, use the Stereo Delay node.

Delay Inputs

Input	Description
In	The audio signal to apply delay to.
Delay Time	The amount of time to delay the audio (in seconds).
Dry Level	The level for the unprocessed (dry) signal
Wet Level	The level for the processed (wet) signal.
Feedback	The amount of feedback to use.

Delay Outputs

Output	Description
Out	The delayed audio signal.

Diffuser

The Diffuser node applies diffusion to the incoming audio.

Diffuser Inputs

Input	Description
Input Audio	The audio to apply diffusion to.
Depth	The number of filters to use to diffuse the audio (between 1 and 5). This will not update while running.
Feedback	The amount of feedback to use on each diffuser (between 0 and 1).

Diffuser Outputs

Output	Description
Output Audio	The diffused audio.

Stereo Delay

The Stereo Delay node provides multi-channel buffer delay. Like the Delay node, which provides mono buffer delay, this node supports dry level, wet level, and feedback, but also supports additional delay modes.

Stereo Delay Inputs

Input	Description
In Left / Right	The input audio signals (left / right channels) to apply delay to.
Delay Mode	The delay method to use: Normal: The left input mixes with the left delay output and feeds to the left output. Cross: The left input mixes with the right delay output and feeds to the right output. Ping Pong: The left input mixes with the left delay output and feeds to the right output.
Delay Time	The amount of time to delay the audio (in seconds).
Delay Ratio	The ratio of delay to apply to the left and right channels. This means channels can have different delay amounts. For example, a value of -1 applies no delay to the left channel while fully delaying the right channel, which can be useful for stereo channel decorrelation.
Dry Level	The level for the unprocessed (dry) signal
Wet Level	The level for the processed (wet) signal.
Feedback	The amount of feedback to use.

Stereo Delay Outputs

Output	Description
Out Left / Right	The output audio signal (left / right channels).

Dynamics

Compressor

The Compressor node lowers the dynamic range of an input audio signal.

Compressor Inputs

Input	Description
Audio	The audio signal to compress.
Ratio	The ratio of gain reduction to apply. For example, a value of 1 produces no gain reduction and a value greater than 1 produces gain reduction.
Threshold dB	The amplitude threshold (in decibels) above which gain will be reduced.
Attack Time	The amount of time it takes for audio above the Threshold (dB) to reach its compressed volume level.
Release Time	The amount of time it takes for audio below the Threshold (dB) to return to its original volume level.
Lookahead Time	The amount of time it takes to delay the compressed signal behind the analyzed input signal.
Knee	A decibel value that determines how hard or soft the gain reduction blends. A value of 0 dB provides no blending.
Sidechain	(Optional) An external audio signal to control the compressor with. If unset, the input audio signal is used.
Envelope Mode	The envelope-following method the compressor will use for gain detection: MS: Envelope follows a running Mean Squared of the audio signal. RMS: Envelope follows a running Root Meat Squared of the audio signal. Peak: Envelope follows the peaks in the audio signal.
Analog Mode	If enabled, use Analog Mode for the compressor's envelope follower.
Upwards Mode	If enabled, an upwards compressor is used instead of the standard downwards compressor.
Wet/Dry	The ratio between the processed (wet) and the unprocessed (dry) signal. For example, a value of 0 is fully dry and a value of 1 is fully wet.

Compressor Outputs

Output	Description
Audio	The output audio signal with the compressor effect applied.
Gain Envelope	The amount of gain applied to the signal.

Decibels to Linear Gain

The Decibels to Linear Gain node converts a logarithmic (dB) gain value to a linear gain value.

Decibels to Linear Gain Inputs

Input	Description
Decibels	The input logarithmic (dB) gain value.

Decibels to Linear Gain Outputs

Output	Description
Linear Gain	The output linear gain value.

Limiter

The Limiter node prevents a signal from going above a given threshold.

Limiter Inputs

Input	Description
Audio	The input audio signal to be limited.
Input Gain dB	The amount of gain (in decibels) to apply to the input before limiting.
Threshold dB	The amplitude threshold (in decibels) above which gain will be reduced.
Release Time	The time it takes for audio below the threshold to return to its original volume level.
Knee	The knee mode determines if the gain reduction blends are hard or soft.

Limiter Outputs

Output	Description
Audio	The limited audio signal.

Linear Gain to Decibels

The Linear Gain to Decibels node converts a linear gain value to a logarithmic (dB) gain value.

Linear Gain to Decibels Inputs

Input	Description
Linear Gain	The input linear gain value.

Linear Gain to Decibels Outputs

Output	Description
Decibels	The output logarithmic (dB) gain value.

Envelopes

MetaSounds provide Envelope nodes so audio designers can change aspects of their sounds over time. Each type of Envelope node has two different versions to support Audio (audio-rate) and Float (block-rate) data types.

Audio designers can customize their curve values using the various curve values contained within the nodes. For attack-time values, a curve value of less than 1.0 is a logarithmic curve (which rises quickly at first and slower near the end), and a value greater than 1.0 is an exponential curve (rises slower at first and more quickly near the end). Decay and release curves have the opposite behavior. Values of 1.0 for these curves are linear curves.

AD Envelope

The AD Envelope node generates an attack-decay envelope value output when triggered.

This node provides an additional option for looping the Attack-Decay curve similarly to a Low Frequency Oscillator (LFO) or Wave Generator. When paired with a Map Range node, this can be used to great effect in a variety of applications.

AD Envelope Inputs

Input	Description
Trigger	The trigger on which to start the attack phase of the envelope generator.
Attack Time	The amount of time (in seconds) to reach the maximum envelope value (1.0).
Delay Time	The amount of time (in seconds) to reach the minimum envelope value (0.0).
Attack Curve	The exponential curve factor of the attack phase. For example, a value of 1.0 produces linear growth, a value less than 1.0 produces logarithmic growth, and a value greater than 1.0 produces exponential growth.
Decay Curve	The exponential curve factor of the decay phase. For example, a value of 1.0 produces linear decay, a value greater than 1.0 produces logarithmic decay, and a value less than 1.0 produces exponential decay.
Looping	If enabled, the envelope will loop.

AD Envelope Outputs

Output	Description
On Trigger	Triggers when the envelope is triggered.
On Done	Triggers when the envelope finishes or loops back if looping is enabled.
Out Envelope	The output value of the envelope.

ADSR Envelope

The ADSR Envelope node generates an attack-decay-sustain-release envelope value output when triggered. This node is similar to the AD Envelope node, but it requires a separate release trigger for the release phase of the envelope to begin.

ADSR Envelope Inputs

Input	Description
Trigger Attack	The trigger on which to start the attack phase of the envelope generator.
Trigger Release	The trigger on which to start the release phase of the envelope generator.
Attack Time	The amount of time (in seconds) to reach the maximum envelope value (1.0).
Delay Time	The amount of time (in seconds) to reach the minimum envelope value (0.0).
Sustain Level	The sustain level of the envelope.
Release Time	The release time of the envelope.
Attack Curve	The exponential curve factor of the attack phase. For example, a value of 1.0 produces linear growth, a value less than 1.0 produces logarithmic growth, and a value greater than 1.0 produces exponential growth.
Decay Curve	The exponential curve factor of the decay phase. For example, a value of 1.0 produces linear decay, a value greater than 1.0 produces logarithmic decay, and a value less than 1.0 produces exponential decay.
Release Curve	The exponential curve factor of the release phase. For example, a value of 1.0 produces linear release, a value greater than 1.0 produces logarithmic release, and a value less than 1.0 produces exponential release.

ADSR Envelope Outputs

Output	Description
On Attack Triggered	Triggers when the envelope attack phase is triggered.
On Decay Triggered	Triggers when the envelope decay phase is triggered.
On Sustain Triggered	Triggers when the envelope sustain phase is triggered.
On Release Triggered	Triggers when the envelope release phase is triggered.
On Done	Triggers when the envelope is finished.
Out Envelope	The output value of the envelope.

Crossfade

The Crossfade node blends between inputs linearly using a provided block-rate float parameter. There are multiple versions of this node to support different input counts (between 2 and 8).

Crossfade Inputs

Input	Description
Crossfade Value	The value which represents the current blend between the provided inputs. For example, a value of 0.5 for input values of 2 and 4 will result in an output of 3.
In X	The input corresponding with position X.

Crossfade Outputs

Output	Description
Out	The value produced from the crossfade.

External IO

Wave Writer

The Wave Writer node writes audio signals to disk. There are multiple versions of this node to support different channel amounts (between 1 and 8).

The file is rendered at 48,000 Hz and is saved to the Saved > AudioCaptures folder.

Wave Writer Inputs

Input	Description
Filename Prefix	The filename prefix used for the output file.
Enabled	If enabled, this node will write audio signals to disk.
In X	The audio input corresponding with channel X.

Filters

Biquad Filter

The Biquad Filter node provides a simple two-pole biquad filter that supports a variety of configurations.

Biquad Filter Inputs

Input	Description
In	The audio to be biquad filtered.
Cutoff Frequency	The value of the cutoff frequency.
Bandwidth	When applicable, controls the bandwidth value of the current filter type.
Gain (dB)	The gain (in decibels) applied to the band when in Parametric mode.
Type	The type of biquad filter to use.

Biquad Filter Outputs

Output	Description
Out	The biquad-filtered audio.

Bitcrusher

The Bitcrusher node downsamples and lowers the bit-depth of an incoming audio signal.

Bitcrusher Inputs

Input	Description
Audio	The audio signal to bitcrush.
Sample Rate	The sampling frequency to downsample the audio to.
Bit Depth	The bit resolution to reduce the audio to.

Bitcrusher Outputs

Output	Description
Audio	The bitcrushed audio signal.

Dynamic Filter

The Dynamic Filter node filters a band of audio based on the strength of the input signal.

Dynamic Filter Inputs

Input	Description
Audio	The audio signal to filter.
Sidechain	(Optional) An external audio signal to control the filter with. If not set, the input audio signal is used.
FilterType	The filter shape to use.
Frequency	The center frequency of the filter.
Q	The filter's Q, or resonance, which controls the steepness of the filter.
Threshold dB	The amplitude threshold (dB) above which gain is reduced.
Ratio	The amount of gain reduction to apply. A value of 1 applies no reduction and a higher value provides more reduction.
Knee	A decibel value that determines how hard or soft the gain reduction blends. A value of 0 dB provides no blending.
Range	The maximum gain reduction allowed (in decibels). A negative value applies compression and a positive value flips it into an expander.
Gain (dB)	The amount of make-up gain (in decibels) to apply.
AttackTime	The amount of time (in seconds) it takes the audio above the threshold to reach its compressed volume level.
ReleaseTime	The amount of time (in seconds) it takes for the audio below the threshold to return to its original volume level.
EnvelopeMode	The envelope-following method the compressor uses for gain detection.
AnalogMode	If enabled, analog mode is used for the compressor's envelope follower.

Dynamic Filter Outputs

Output	Description
Audio	The filtered audio signal.

Ladder Filter

The Ladder Filter node provides a virtual analog filter that has a pleasing and classic rolloff and resonance.

Ladder Filter Inputs

Input	Description
In	The audio to be processed by the ladder filter.
Cutoff Frequency	The value of the cutoff frequency.
Resonance	The value of the filter resonance.

Ladder Filter Outputs

Output	Description
Out	The ladder filtered audio.

Mono Band Splitter

The Mono Band Splitter node splits incoming audio into separate frequency bands. There are multiple versions of this node to support different input and output counts (between 2 and 5).

Mono Band Splitter Inputs

Input	Description
In	The base audio input channel.
Filter Order	The steepness of the crossover filters.
Phase Compensate	If enabled, each band is phase-compensated so they can be summed back together correctly.
Crossover X	An additional audio input corresponding to channel X.

Mono Band Splitter Outputs

Output	Description
Band X Out	The audio output corresponding to channel X.

One-Pole High Pass Filter

The One-Pole High Pass Filter node is a computationally cheap filter useful for a number of simple applications, such as simulating occlusion.

One-Pole High Pass Filter Inputs

Input	Description
In	The audio signal to be filtered.
Cutoff Frequency	The value of the cutoff frequency.

One-Pole High Pass Filter Outputs

Output	Description
Out	The filtered audio signal.

One-Pole Low Pass Filter

The One-Pole Low Pass Filter node is a computationally cheap filter useful for a number of simple applications, such as simulating air absorption

One-Pole Low Pass Filter Inputs

Input	Description
In	The audio signal to be filtered.
Cutoff Frequency	The value of the cutoff frequency.

One-Pole Low Pass Filter Outputs

Output	Description
Out	The filtered audio signal.

Sample And Hold

The Sample And Hold node outputs a single value of the input audio signal when triggered.

Sample And Hold Inputs

Input	Description
Sample And Hold	The trigger on which to sample and hold the input audio.
In	The audio signal to sample.

Sample And Hold Outputs

Output	Description
On Sample And Hold	Triggers when the Sample and Hold input is triggered.
Out	The sampled audio signal.

State Variable Filter

The State Variable Filter node provides a virtual analog filter used in many synthesis applications.

State Variable Filter Inputs

Input	Description
In	The audio to be processed by the filter.
Cutoff Frequency	The value of the cutoff frequency.
Resonance	The value of the filter resonance.
Band Stop Control	The control value applied to the band stop output.

State Variable Filter Outputs

Output	Description
Low Pass Filter	The low pass filter output.
High Pass Filter	The high pass filter output.
Band Pass	The band pass filter output.
Band Stop	The band stop filter output.

Stereo Band Splitter

The Stereo Band Splitter node splits incoming audio into separate frequency bands. There are multiple versions of this node to support different input and output counts (between 2 and 5).

Stereo Band Splitter Inputs

Input	Description
In L / R	The base audio input channels.
Filter Order	The steepness of the crossover filters.
Phase Compensate	If enabled, each band is phase-compensated so that they can be summed back together correctly.
Crossover X	An additional audio input corresponding to channel X.

Stereo Band Splitter Outputs

Output	Description
Band X L / R	The audio output corresponding to channel X (in the left / right channel).

Generators

MetaSounds have several audio-rate generators which provide options for frequency modulation.

With the exception of the Noise node, all of these nodes support sync triggering which resets their phase. When combined with an audio-rate trigger repeat or a threshold trigger, this can create many unique synthesis effects.

Low-Frequency Oscillator (LFO)

The LFO node provides a low-frequency oscillator which you can use to create a variety of audio effects, such as phasing, vibrato, and tremolo.

LFO Inputs

Input	Description
Frequency	The frequency (Hz) of the LFO (clamped at block rate).
Shape	The wave shape of the LFO.
Min / Max Value	The minimum / maximum output values.
Sync	Resets the phase of the generator. You can use this in conjunction with other nodes to get audio-rate phase synced generators.
Phase Offset	The phase offset (in degrees, between 0 and 360).
Pulse Width	The pulse width (between 0 and 1).

LFO Outputs

Output	Description
Out	The output value of the LFO (clamped at block rate).

Noise

The Noise node generates either pink or white noise.

Noise Inputs

Input	Description
Seed	The seed for the random number generator. The default value of -1 uses the current time.
Type	The type of noise to generate.

Noise Outputs

Output	Description
Audio	The generated noise output.

Saw

The Saw node emits an audio signal of a saw wave with the given properties.

Saw Inputs

Input	Description
Enabled	If enabled, the oscillator produces a signal.
Bi Polar	If enabled, the output is bi-polar (-1, 1). Otherwise, the output is uni-polar (0, 1).
Frequency	The base frequency of the oscillator (in Hz).
Modulation	An audio-rate input to modulate the base frequency.
Sync	Resets the phase of the generator. You can use this in conjunction with other nodes to get audio-rate phase synced generators.
Phase Offset	The phase offset (in degrees, between 0 and 360).
Glide	The amount of glide (smooth interpolation over time) used when changing frequencies. For example, a value of 0.0 will produce no glide and a value of 1.0 produces lots of glide.
Type	The generator type used to make the saw wave: Poly Smooth: Generates a smooth version of the saw wave. Trivial: Uses a basic implementation to generate a saw wave.

Saw Outputs

Output	Description
Audio	The saw wave audio signal.

Sine

The Sine node emits an audio signal of a sinusoid with the given properties.

Sine Inputs

Input	Description
Enabled	If enabled, the oscillator produces a signal.
Bi Polar	If enabled, the output is bi-polar (-1, 1). Otherwise, the output is uni-polar (0, 1).
Frequency	The base frequency of the oscillator (in Hz).
Modulation	An audio-rate input to modulate the base frequency.
Sync	Resets the phase of the generator. You can use this in conjunction with other nodes to get audio-rate phase synced generators.
Phase Offset	The phase offset (in degrees, between 0 and 360).
Glide	The amount of glide (smooth interpolation over time) used when changing frequencies. For example, a value of 0.0 will produce no glide and a value of 1.0 produces lots of glide.
Type	The generator type used to make the sinusoid: 2D Rotation: Rotates around the unit circle to generate the sine wave. Pure Math: Uses the standard math library to generate the sine wave (most expensive method). Bhaskara: Uses the Bhaskara technique to approximate the sine wave. Wave Table: Uses a wave table to generate the sine wave.

Sine Outputs

Output	Description
Audio	The sinusoid audio signal.

Square

The Square node emits an audio signal of a square wave with the given properties.

Square Inputs

Input	Description
Enabled	If enabled, the oscillator produces a signal.
Bi Polar	If enabled, the output is bi-polar (-1, 1). Otherwise, the output is uni-polar (0, 1).
Frequency	The base frequency of the oscillator (in Hz).
Modulation	An audio-rate input to modulate the base frequency.
Sync	Resets the phase of the generator. You can use this in conjunction with other nodes to get audio-rate phase synced generators.
Phase Offset	The phase offset (in degrees, between 0 and 360).
Glide	The amount of glide (smooth interpolation over time) used when changing frequencies. For example, a value of 0.0 will produce no glide and a value of 1.0 produces lots of glide.
Type	The generator type used to make the square wave: Poly Smooth: Generates a smooth version of the Square wave. Trivial: Uses a basic implementation to generate a Square wave.
Pulse Width	The relative pulse width of the square wave.

Square Outputs

Output	Description
Audio	The square wave audio signal.

Triangle

The Triangle node emits an audio signal of a triangle wave with the given properties.

Triangle Inputs

Input	Description
Enabled	If enabled, the oscillator produces a signal.
Bi Polar	If enabled, the output will be bi-polar (-1, 1). Otherwise, the output will be uni-polar (0, 1).
Frequency	The base frequency of the oscillator (in Hz).
Modulation	An audio-rate input to modulate the base frequency.
Sync	Resets the phase of the generator. You can use this in conjunction with other nodes to get audio-rate phase synced generators.
Phase Offset	The phase offset (in degrees, between 0 and 360).
Glide	The amount of glide (smooth interpolation over time) used when changing frequencies. For example, a value of 0.0 will produce no glide and a value of 1.0 produces lots of glide.
Type	The generator type used to make the triangle wave: Poly Smooth: Generates a smooth version of the Triangle wave. Trivial: Uses a basic implementation to generate a Triangle wave.

Triangle Outputs

Output	Description
Audio	The triangle wave audio signal.

Math

MetaSounds come with a variety of nodes that perform basic math operations on the given inputs.

Operations on Audio data types are executed at a per-sample level.

Add

The Add node performs addition operations on provided inputs. This node has different versions which support several common data types, including: Audio, Float to Audio, Float, Int32, and Time.

Clamp

The Clamp node returns the clamped value of the input within the given value range. This node has different versions which support several common data types, including: Audio, Float, and Int32.

Clamp Inputs

Input	Description
In	The input value to clamp.
Min / Max	The min / max value to clamp the input value to.

Clamp Outputs

Output	Description
Value	The clamped value.

Divide

The Divide node performs division operations on provided inputs. This node has different versions which support several common data types, including: Float, Int32, and Time by Float.

Linear To Log Frequency

The Linear To Log Frequency node converts a linear space input value to a log-frequency output.

Linear To Log Frequency Inputs

Input	Description
Value	The linear input value to map to a log frequency output.
Min / Max Domain	The min / max domain for the input value. The input and output values are clamped to this domain.
Min / Max Range	The min / max positive range for the output frequency (Hz) value. The input and output values are clamped to this range.

Linear To Log Frequency Outputs

Output	Description
Frequency	The output frequency (Hz) that is the log frequency of the input value.

Log

The Log node calculates the float-base logarithm of another float.

Map Range

The Map Range node maps an input value in a given input range to a given output range. The results can also be clamped. This node has different versions which support several common data types, including: Audio, Float, and Int32. These nodes are analogous to the Blueprint Map Range nodes.

The Audio version of this node does a per-sample mapping. This is useful when mapping audio-rate signals to audio-rate modulation parameters, such as Frequency Modulator in FM synthesis.

Map Range Inputs

Input	Description
In	The input value to map.
In Range A / B	The minimum and maximum input value range.
Out Range A / B	The minimum and maximum output value range.
Clamped	If enabled, the input will be clamped to the specified input range.

Map Range Outputs

Output	Description
Out Value	The mapped output value.

Max

The Max node returns the higher value (max) of A and B. This node has different versions which to support several common data types, including: Audio, Float, and Int32.

Max Inputs

Input	Description
A / B	The input values to compare.

Max Outputs

Output	Description
Value	The higher value (max) of A and B.

Min

The Min node returns the lower value (min) of A and B. This node has different versions which support several common data types, including: Audio, Float, and Int32.

MinInputs

Input	Description
A / B	The input values to compare.

Min Outputs

Output	Description
Value	The lower value (min) of A and B.

Modulo

The Modulo node returns the remainder of a division operation of two given Int32 values.

Multiply

The Multiply node performs multiplication operations on provided inputs. This node has different versions which support several common data types, including: Audio by Float, Audio, Float, Int32, and Time by Float.

This node can be used to provide ring-modulation type effects and audio-rate amplitude modulation.

Power

The Power node raises a given Float to the power of another Float.

Subtract

The Subtract node performs subtraction operations on provided inputs. This node has different versions which support several common data types, including: Audio, Float, Int32, and Time.

Mix

MetaSounds provide two node types to create audio mixes, the Mono Mixer node and the Stereo Mixer node. These nodes have different versions which support between 2 and 8 input audio buffers, which are combined into a single buffer by using the input channel's corresponding gain values and summing them together.

The gain values are not clamped so they can be used for attenuating and inverting the audio signal.

These nodes are useful for mapping audio-rate buffers to different ranges for modulating various audio-rate-capable parameters.

Mono Mixer

Stereo Mixer

Music

Frequency To MIDI

The Frequency To MIDI node converts a frequency value (in Hz) to a standard MIDI scale note value (where middle C is 60).

Frequency To MIDI Inputs

Input	Description
Frequency In	The input frequency value (in Hz).

Frequency To MIDI Outputs

Output	Description
Out MIDI	The output MIDI note value.

MIDI Note Quantizer

The MIDI Note Quantizer node quantizes a MIDI note to the nearest note that matches the provided criteria.

MIDI Note Quantizer Inputs

Input	Description
Note In	The MIDI note to quantize.
Root Note	The MIDI note to treat as the root. For example, a value of 0 equals C, a value of 1 equals D, and so on. The octave does not matter. Additionally, all values less than 0 clamp to 0.
Scale Degrees	An array containing a set of notes (in ascending order) representing half steps. The array must start with 0.0 to represent the root note and the highest value in the array must represent the root note in a higher octave, such as 12.0 for a single octave range or 24.0 for a two octave range.

MIDI Note Quantizer Outputs

Output	Description
Note Out	The quantized note.

MIDI To Frequency

The Frequency to MIDI node converts a standard MIDI scale note value (where middle C is 60) to a frequency value (in Hz). This node has two different versions which support Float and Int32 data types respectively.

You can use this node to musically control generators that take frequencies (in Hz) as an input. Additionally, the Float version can take fractional MIDI note values, which can be useful for microtonality and custom tuning.

MIDI To Frequency Inputs

Input	Description
MIDI In	The input value which represents a MIDI note value.

MIDI To Frequency Outputs

Output	Description
Out Frequency	The output frequency value (in Hz).

Scale to Note Array

The Scale to Note Array node returns an array of floating-point numbers representing notes of the selected scale.

This node can be useful when creating procedural music by using the Chord Tones Only toggle to switch between full scale and chord tones.

Scale to Note Array Inputs

Input	Description
Scale Degrees	The preset scale to get the notes for.
Chord Tones Only	If enabled, a subset of the scale representing chord tones is returned. For example, scale degrees of 1, 3, 5, and 7.

Scale to Note Array Outputs

Output	Description
Scale Array Out	The array representation of the scale as half-steps above the root. The set is inclusive at both ends (starting at 0.0f and ending at 12.0f).

Random

MetaSounds provide several Random nodes categorized by their output value type, including Bool, Float, Int, and Time. These nodes output a random value from their input type and a seed.

Using the Reset trigger with an identical seed will produce the same results. This is useful to get randomized repetition.

Random Inputs

Input	Description
Next	The trigger on which to generate the next random value.
Reset	The trigger on which to reset the random sequence with the supplied seed.
Seed	The seed value to use for the randomization. The default value of -1 uses a random seed.
Min / Max	The inclusive range of the random value.

Random Outputs

Output	Description
On Next	Triggers when the Next input is triggered.
On Reset	Triggers when the Reset input is triggered.
Value	The randomly generated value.

Spatialization

ITD Panner

The ITD Panner node pans an input audio signal using an interaural time delay method.

ITD Panner Inputs

Input	Description
In	The input audio to spatialize.
Angle	The sound source angle (in degrees). A value of 90 degrees is front, 0 degrees is right, 270 degrees is behind, and 180 degrees is left.
Distance Factor	The normalized distance factor (0.0 to 1.0) to use for Interaural Level Difference (ILD) calculations. A value of 0.0 is near and a value of 1.0 is far. The further away the input audio is, the less difference in levels (gain) between the ears.
Head Width	The width (in centimeters) of the listener's head.

ITD Panner Outputs

Output	Description
Out Left / Right	The audio output (left / right channel).

Mid-Side Decode

The Mid-Side Decode node converts a stereo signal with mid and side channels to left and right channels.

Mid-Side Decode Inputs

Input	Description
In Mid / Side	The audio channels to convert.
Spread Amount	The amount of stereo spread. A value of 0.0 is no spread, a value of 0.5 is the original signal, and a value of 1.0 is fully wide.
Equal Power	If enabled, an equal power relationship between the input audio channels will be maintained.

Mid-Side Decode Outputs

Output	Description
Out Left / Right	The output audio channels.

Mid-Side Encode

The Mid-Side Encode node converts a stereo signal with left and right channels to mid and side channels.

Mid-Side Encode Inputs

Input	Description
In Left / Right	The audio channels to convert.
Spread Amount	The amount of stereo spread. A value of 0.0 is no spread, a value of 0.5 is the original signal, and a value of 1.0 is fully wide.
Equal Power	If enabled, an equal power relationship between the input audio channels is maintained.

Mid-Side Encode Outputs

Output	Description
Out Mid / Side	The output audio channels.

Stereo Panner

The Stereo Panner node pans an input audio signal to left and right outputs.

Stereo Panner Inputs

Input	Description
In	The input audio signal to pan.
Pan Amount	The amount to pan the audio signal (-1.0 is fully left, 1.0 is fully right).
Panning Law	The panning law to use: Equal Power: The power of the audio signal is constant while panning. Linear: The amplitude of the audio signal is constant while panning.

Stereo Panner Outputs

Output	Description
Out Left / Right	The output audio signal (left / right channels).

Triggers

Trigger Accumulate

The Trigger Accumulate node triggers once all connected input triggers have been triggered at least once. There are multiple versions of this node in order to support different input counts (between 1 and 8).

This node is can be useful to detect when multiple Wave Player nodes to finish before triggering the On Finished Output trigger.

Trigger Accumulate Inputs

Input	Description
In X	The trigger input(s).
Auto Reset	The trigger on which the accumulation on this node is reset.

Trigger Accumulate Outputs

Output	Description
Out	Triggers when all input triggers have been accumulated.

Trigger Any

The Trigger Any node triggers once any of the connected input triggers activate. This node has different versions which support different input counts (between 2 and 8).

This is a useful node when you want to have many different trigger sources execute another node's input.

Trigger Any Inputs

Input	Description
In X	The trigger input(s).

Trigger Any Outputs

Output	Description
Out	Triggers when any input trigger is triggered.

Trigger Compare

The Trigger Compare node triggers either true or false based on comparing connected inputs. This node has different versions which support several common data types, including: Bool, Float, and Int32.

Trigger Compare Inputs

Input	Description
Compare	The trigger on which to compare A and B.
A / B	The values to compare.
Type	The type of comparison to make.

Trigger Compare Outputs

Output	Description
True / False	Triggers with the resulting trigger after making the comparison.

Trigger Control

The Trigger Control node provides controls to allow or block trigger signals from passing through to the output.

Trigger Control Inputs

Input	Description
Trigger In	The input trigger to control.
Open	The trigger on which to allow the input trigger to pass through.
Close	The trigger on which to block the input trigger to pass through.
Toggle	The trigger on which to toggle the open/closed state of this node.
Start Closed	If enabled, the node will start in a closed state.

Trigger Control Outputs

Output	Description
Trigger Out	The output trigger that passes through if the node is open.

Trigger Counter

The Trigger Counter node counts the connected input trigger activations.

This node is useful for sequencing array inputs and a large number of other procedural use cases.

Trigger Counter Inputs

Input	Description
In	The input trigger for which to count activations.
Reset	The trigger on which to reset the counter to zero and the value back to the start value.
Start Value	The value to start with on initialization and when reset.
Step Size	The value to add to the current value for each input trigger. This can be negative.
Reset Count	The number of input triggers to count before automatically resetting. If the value is set to 0, the node won't automatically reset.

Trigger Counter Outputs

Output	Description
On Trigger	Triggers when the input trigger is triggered and the count is updated.
On Reset	Triggers when the input reset is triggered or if the counter automatically resets.
Count	The current trigger count.
Value	The current value.

Trigger Delay

The Trigger Delay node executes a trigger after a given delay time from the most recent execution of the input trigger.

This node is similar to the Trigger Pipe node, but differs by only considering the most recent trigger execution. This means that additional triggers that happen within the delay time will reset the timer and cause the output trigger to be delayed again.

Trigger Delay Inputs

Input	Description
In	The input trigger to delay.
Reset	The trigger on which to reset the delay and clear the execution task, if it is pending.
Delay Time	The amount of time to delay the trigger (in seconds).

Trigger Delay Outputs

Output	Description
Out	The delayed output trigger.

Trigger Filter

The Trigger Filter node responds to a trigger by randomly activating one of the two output triggers.

Trigger Filter Inputs

Input	Description
Trigger	The trigger on which to randomly activate an output trigger.
Reset	The trigger on which to reset the random sequence with the provided seed.
Seed	The seed value to use for the randomization. A value of -1 will use a random seed.
Probability	The probability that a particular output trigger will get activated. For example, a value of 0.0 is always heads, a value of 1.0 is always tails, and 0.5 is equal odds.

Trigger Filter Outputs

Output	Description
Heads / Tails	The possible output triggers.

Trigger On Threshold

The Trigger On Threshold node operates as an edge detector and triggers when the input audio crosses a given threshold value while moving in the specified direction.

If set to Rising Edge, a trigger is output when the signal crosses the threshold with a positive slope. This is useful when paired with a generator node and connected to another generator's sync trigger input.

Trigger On Threshold Inputs

Input	Description
In	The input audio signal.
Threshold	The threshold at which to trigger output.
Type	The type of trigger threshold.

Trigger On Threshold Outputs

Output	Description
Out	The output threshold trigger.

Trigger On Value Change

The Trigger On Value Change node triggers when a given value changes. This node has different versions which support several common data types, including: Bool, Float, and Int32.

Trigger On Value Change Inputs

Input	Description
Value	The input value to watch.

Trigger On Value Change Outputs

Output	Description
Trigger	The output trigger.

Trigger Once

The Trigger Once node triggers the first time an input trigger is activated and ignores all other occurrences, unless reset.

Trigger Once Inputs

Input	Description
Trigger In	The input trigger.
Reset	The trigger on which to open the node and allow another trigger through.
Start Closed	If enabled, the node is closed when playback begins.

Trigger Once Outputs

Output	Description
Trigger Out	The output trigger.

Trigger Pipe

The Trigger Pipe node delays execution of all input trigger signals by the given delay.

This node is similar to the Trigger Delay node, but does not reset the timer upon receiving additional triggers.

Trigger Pipe Inputs

Input	Description
In	The input trigger to delay.
Reset	The trigger on which to reset the trigger delay and clear any pending execution tasks.
Delay Time	The time to delay the input trigger (in seconds).

Trigger Pipe Outputs

Output	Description
Out	The delayed output trigger.

Trigger Repeat

The Trigger Repeat node emits a trigger periodically at a given sample-accurate and arbitrarily-precise rate.

Trigger Repeat Inputs

Input	Description
Start / Stop	The triggers on which to start or stop executing periodic output triggers.
Period	The period to trigger (in seconds).

Trigger Repeat Outputs

Output	Description
RepeatOut	The periodically generated output trigger.

Trigger Route

The Trigger Route node routes different input values to a single output value. This node has multiple versions for different input counts (between 2 and 8) and for each supported data type, including: Audio, Bool, Float, Int32, and Time.

Trigger Route Inputs

Input	Description
Set X	The input triggers which initialize the routing. The default option is 0.
Value X	The input value to route to the output when triggered by its corresponding trigger.

Trigger Route Outputs

Output	Description
On Set	Triggers when any of the input triggers are set.
Value	The output value set by an activated input trigger.

Trigger Sequence

The Trigger Sequence node responds to input triggers by sending the next output trigger in a sequence. This node has multiple versions which provide different numbers of output triggers (between 2 and 8).

Trigger Sequence Inputs

Input	Description
In	The input trigger.
Reset	The trigger on which to reset the sequence back to 0.
Loop	If enabled, the sequence automatically loops back to 0 once all triggers have been activated.

Trigger Sequence Outputs

Output	Description
Out X	The trigger outputs in sequence.

Trigger Toggle

The Trigger Toggle node toggles a Bool value on or off.

Trigger Toggle Inputs

Input	Description
On / Off	The trigger on which to toggle the Bool output on or off.
Init	The initial states of the Bool.

Trigger Toggle Outputs

Output	Description
Out	Triggers when the Bool is toggled.
Value	The current Bool value.

Value

The Value node sets a variable value on a trigger. This node has different versions for each of the supported data types, including: Bool, Float, Int32, and String.

Value Inputs

Input	Description
Set	The trigger on which to write the set value to the output.
Reset	The trigger on which to reset the value to the initial value.
Init Value	The value to initialize the output value to.
Target Value	The value to set the output to when triggered.

Value Outputs

Output	Description
On Set	Triggers when the value is set.
On Reset	Triggers when the value is reset.
Output Value	The current output value.