LLM MetaSound

DSL-driven MetaSound audio generation for Unreal Engine 5. The agent writes .llmmetasound JSON, the editor turns it into a real UMetaSoundSource or UMetaSoundPatch — generators, filters, envelopes, mixers, bus I/O, with type-safe edges.

Skill file: skills/llm-metasound/SKILL.md

---

When the Agent Loads It

The agent loads this skill when the user asks to:

• Create or design a UE5 MetaSound graph (UMetaSoundSource or UMetaSoundPatch)
• Convert an audio description into a .llmmetasound file
• Inspect or modify an existing MetaSound JSON
• Look up a MetaSound node type (Oscillators, Filters, Envelopes, Mixers, etc.)
• Query node input/output ports, types, and default values

Triggers: .llmmetasound, MetaSound, audio, sound, oscillator, filter, envelope, mixer, UMetaSoundSource, UMetaSoundPatch.

---

Prerequisites

Requirement	Notes
UE 5.7+	Engine version
LLM MetaSound plugin	Distributed via this repository (Fab listing coming soon)
Enabled in editor	Edit → Plugins → AI → LLM MetaSound → restart editor
MetaSound engine plugin	Built into UE 5.7; no extra install

---

Quick Example

Ask the agent:

"Give me a triangle wave at 440Hz with a short attack-release envelope."

The agent produces a .llmmetasound file:

{
  "Metadata": {
    "NodeName": "MyTriangle",
    "NodeType": "MetasoundSource",
    "MetasoundDescription": "Triangle wave with AR envelope"
  },
  "Inputs": [],
  "Outputs": [],
  "Nodes": [
    {
      "NodeID": 1,
      "ClassName": "Triangle",
      "Name": "Osc1",
      "InputDefaults": {
        "Frequency": { "LiteralType": "Float", "AsFloat": 440.0 }
      }
    },
    {
      "NodeID": 2,
      "ClassName": "Envelope Follower",
      "Name": "AmpEnv",
      "InputDefaults": {
        "Enable":   { "LiteralType": "Boolean", "AsBool": true },
        "Attack":   { "LiteralType": "Float",   "AsFloat": 0.01 },
        "Release":  { "LiteralType": "Float",   "AsFloat": 0.20 }
      }
    }
  ],
  "Edges": [
    { "FromNodeID": 1, "FromVertexID": 0, "ToNodeID": 2, "ToVertexID": 1 }
  ]
}

Save it, open the LLM MetaSound panel, click Generate — the UMetaSoundSource is on disk.

---

What the Skill Knows

The full skill body contains:

• All node types — Oscillators (Sine, Triangle, Saw, Square, Noise), Filters, Envelopes, Mixers, Bus I/O
• Edge types — type-safe vertex connections (auto, audio, trigger, float, int)
• UMetaSoundSource vs UMetaSoundPatch — source = playable sound; patch = reusable audio graph referenced by sources
• Input / Output declarations — exposed parameters, bus bindings
• 6 example files — TriangleSub, SawDiscord, SquareBass, SquareLead, TrianglePad, NoiseBurst
• Builder subsystem — uses UE5's MetaSound Builder Subsystem for robust asset creation

---

Compiling the JSON into an Asset

# Manual: editor panel
Tools → LLM MetaSound Panel → select .llmmetasound file → Generate

# CLI (with llm-easy-shell installed)
metasound generate /Game/Audio/MyTriangle --from MyTriangle.llmmetasound

The MetaSound asset opens in the MetaSound editor.

---

Round-Trip

Already have a MetaSound? Use Export to JSON in the editor panel to dump it to a .llmmetasound file. The agent edits it, you re-generate.

---

Related Skills

• llm-easy-shell → — drive the editor from the CLI.
• llm-easy-shell-lite → — read-only exploration.