Node Types

LLMMetaSound supports all MetaSound node types discovered from the INodeClassRegistry.

Schema File: Plugins/LLMMetaSound/Config/Schemas/LLMMetaSoundSchema.llmmetasoundschema

---

Asset Types

The top-level AssetType field ("Source" or "Patch") is authoritative — when present it takes precedence over the legacy Metadata.NodeType. Both spellings work; new authoring should use AssetType.

Source (UMetaSoundSource)

UMetaSoundSource with transport (OnPlay trigger, auto-connected).

{
  "AssetType": "Source",
  "Metadata": {
    "NodeName": "MySound",
    "MetasoundDescription": "My custom sound"
  }
}

Patch (UMetaSoundPatch)

UMetaSoundPatch — pure DSP patch / subgraph without transport.

{
  "AssetType": "Patch"
}

Channel Layout (OutputFormat)

OutputFormat declares the source's channel layout: "Mono" (default), "Stereo", "Quad", "5dot1", "7dot1". Set it when a node publishes more than one audio output (e.g. a stereo mixer's Out L / Out R) — otherwise a stereo graph on a mono source silently drops a channel.

---

Graph Structure

{
  "AssetType": "Source",
  "Metadata": {
    "NodeName": "TriangleSub",
    "MetasoundDescription": "Triangle wave with sub-octave"
  },
  "Inputs": [
    { "Name": "Gain", "TypeName": "Primitive:Float" },
    { "Name": "Frequency", "TypeName": "Primitive:Float" }
  ],
  "Outputs": [
    { "Name": "Audio", "TypeName": "Primitive:Float" }
  ],
  "Nodes": [
    { "NodeID": 1, "ClassName": "Triangle", "ClassPath": "UE.Triangle.Audio", "Name": "MainOsc", "InputDefaults": {} },
    { "NodeID": 2, "ClassName": "Envelope Follower", "ClassPath": "UE.Envelope Follower", "Name": "AmpEnv", "InputDefaults": {} }
  ],
  "Edges": [
    { "FromNodeID": 1, "FromPinName": "Audio", "ToNodeID": 2, "ToPinName": "In" }
  ]
}

---

Node Fields

Field	Type	Description
NodeID	int	Unique integer ID referenced by edges
ClassName	string	MetaSound node class (e.g., "Oscillator", "Triangle")
Name	string	Display name for the node
Location	object	X, Y position in graph editor
InputDefaults	object	Default values for input pins

---

Input Default Format

"InputDefaults": {
  "Frequency": { "LiteralType": "Float", "AsFloat": 440.0 },
  "Enable": { "LiteralType": "Boolean", "AsBool": true }
}

Literal Types

LiteralType	Field	Description
Float	AsFloat	Float value
Boolean	AsBool	Boolean value
Int	AsInt	Integer value
String	AsString	String value

---

Edge Format

"Edges": [
  { "FromNodeID": 1, "FromPinName": "Audio", "ToNodeID": 2, "ToPinName": "In" }
]

Field	Type	Description
FromNodeID	int	Source node ID
FromPinName	string	Source pin name, resolved against the engine's live vertex list
ToNodeID	int	Target node ID
ToPinName	string	Target pin name, resolved against the engine's live vertex list
FromVertexID / ToVertexID	int	Deprecated legacy pin indices — used only when the corresponding *PinName is empty

Pin names are stable across UE versions and self-document intent (e.g. Audio, In, Out, Audio Envelope). Prefer them for new authoring.

---

Node Categories

Generators

ClassName	Description
Triangle	Triangle wave oscillator
Saw	Sawtooth wave oscillator
Square	Square wave oscillator
Noise	White noise generator
LFO	Low frequency oscillator

Filters

ClassName	Description
Ladder Filter	Ladder filter (LP/HP/BP)
Biquad	Biquad filter
OnePole	One-pole filter

Envelopes

ClassName	Description
Envelope Follower	Amplitude envelope
ADSR	Attack-Decay-Sustain-Release envelope

Effects

ClassName	Description
Delay	Delay effect
Reverb	Reverb effect
Chorus	Chorus effect
Compressor	Dynamics compressor

Mix

ClassName	Description
Gain	Volume/gain control
Mixer	Multi-channel mixer
MonoToStereo	Mono to stereo conversion
StereoToMono	Stereo to mono conversion

Utility

ClassName	Description
Output	Graph output node
Split	Signal splitter
Merge	Signal merger

---

Common Patterns

Simple Oscillator with Envelope

{
  "AssetType": "Source",
  "Metadata": {
    "NodeName": "TriangleSub",
    "MetasoundDescription": "Triangle wave with envelope"
  },
  "Inputs": [],
  "Outputs": [],
  "Nodes": [
    { "NodeID": 1, "ClassName": "Triangle", "ClassPath": "UE.Triangle.Audio", "Name": "MainOsc", "InputDefaults": { "Frequency": { "LiteralType": "Float", "AsFloat": 110.0 } } },
    { "NodeID": 2, "ClassName": "Envelope Follower", "ClassPath": "UE.Envelope Follower", "Name": "AmpEnv", "InputDefaults": { "Enable": { "LiteralType": "Boolean", "AsBool": true } } }
  ],
  "Edges": [
    { "FromNodeID": 1, "FromPinName": "Audio", "ToNodeID": 2, "ToPinName": "In" }
  ]
}

Oscillator → Filter → Envelope

{
  "AssetType": "Source",
  "Metadata": {
    "NodeName": "SawDiscord",
    "MetasoundDescription": "Sawtooth with filter"
  },
  "Inputs": [],
  "Outputs": [],
  "Nodes": [
    { "NodeID": 1, "ClassName": "Saw", "ClassPath": "UE.Saw.Audio", "Name": "SawOsc", "InputDefaults": { "Frequency": { "LiteralType": "Float", "AsFloat": 175.0 } } },
    { "NodeID": 2, "ClassName": "Ladder Filter", "ClassPath": "UE.Ladder Filter.Audio", "Name": "HPF", "InputDefaults": {} },
    { "NodeID": 3, "ClassName": "Envelope Follower", "ClassPath": "UE.Envelope Follower", "Name": "AmpEnv", "InputDefaults": { "Enable": { "LiteralType": "Boolean", "AsBool": true } } }
  ],
  "Edges": [
    { "FromNodeID": 1, "FromPinName": "Audio", "ToNodeID": 2, "ToPinName": "In" },
    { "FromNodeID": 2, "FromPinName": "Out", "ToNodeID": 3, "ToPinName": "In" }
  ]
}

Graph Interface (with Inputs/Outputs)

{
  "AssetType": "Source",
  "Metadata": {
    "NodeName": "ModularSynth"
  },
  "Inputs": [
    { "Name": "Gain", "TypeName": "Primitive:Float" },
    { "Name": "Frequency", "TypeName": "Primitive:Float" }
  ],
  "Outputs": [
    { "Name": "Audio", "TypeName": "Primitive:Float" }
  ],
  "Nodes": [
    { "NodeID": 1, "ClassName": "Triangle", "Name": "Osc", "InputDefaults": {} }
  ],
  "Edges": []
}