unity-technologies/audio-setup-mixers

Audio Mixer Setup

Routing an Audio Source to a mixer group is a scene edit that only a running Editor can make, so this skill needs a live Editor it can execute C# in. Step 0 establishes that before anything else.

What this skill automates, and what it hands back to you. Inspecting mixers and routing Audio Sources into groups is entirely public Unity API, and that is the tedious part — walking dozens of sources and classifying them by what they play. Creating a mixer or a group has no public API; it exists only on types Unity does not commit to keeping stable. So this skill will not create groups behind your back. It inventories what exists, proposes the routing, asks you to add any missing group in the Audio Mixer window, and then does all the routing itself.

That is a deliberate limit, not a gap to work around. Do not reach for reflection to create groups, and do not hand-edit a .mixer file — mixer structure is not safely authorable blind.

Step 0: Confirm you can run C# in the Editor

Every C# step below runs inside a live Editor through the Unity CLI. The unity-cli skill owns getting you there — installing the CLI, confirming a connected Editor, adding the project's com.unity.pipeline package, telling a genuinely absent Editor apart from one stuck in Safe Mode, and discovering the Editor's command catalog. Follow it first; don't re-derive any of it here.

Two things it can't know for you:

• You need eval in particular, not just a reachable Editor. Confirm it appears in the catalog. Its presence depends on the Pipeline package version, not on the CLI, so a healthy install can still lack it — if it's missing, say so and stop.
• Do not fall back to editing .mixer files by hand. Mixer routing is not safely authorable blind, so an unreachable Editor is a stop, not a cue to improvise.

Once eval is available, that is how each C# step below runs.

Run C# through the connected Editor with the eval command. Discover its parameter shape from unity command --format json rather than assuming one — the inline form is unity command eval --code '<snippet>', and some Pipeline versions also register eval_file for running a snippet from a file. Check the catalog before reaching for eval_file; it is frequently absent. unity command defaults to a 30 second timeout.

Passing C# to eval

eval compiles a statement block, not a file. Two consequences, both of which cause a compile error rather than a warning:

• No using directives. The compiler reads using UnityEngine; as a resource-disposal statement and rejects it (CS0210).
• Types must be fully qualified. A bare AssetDatabase or Volume does not resolve (CS0246 / CS0103), and a bare Object is ambiguous with object (CS0104).

Where a snippet below is written as a file — with usings, for readability, or because it is meant to be saved into the project — qualify the types before passing it to eval.

Step 1: Pre-flight

If the user hasn't explicitly asked for Audio Mixers, confirm that they want to proceed with setting them up.

Then inventory what already exists with the mixer-inventory snippet in references/api.md, run through the Editor as described in Step 0. That gives you every mixer in the project and the group names in each.

It returns a flat list of groups, not the parent/child tree. That is enough to route into, and it is all the public API exposes. If the hierarchy matters for the conversation, ask the user to look at the Audio Mixer window and describe it — don't reach for the non-public tree API to find out.

If the project has no mixer at all, say so and stop rather than improvising one: creating a mixer has no public API. Ask the user to create one (Window → Audio → Audio Mixer, then the + next to Mixers), and pick up from here once it exists.

Step 2: Find scene references

Find all Audio Source components, look at their assigned Generator asset names, and generalize a fitting class or category of the sound name, ideally something already existing. Examples for Audio Clip asset names:

• "FootStep4_Sound" -> Foley
• "Dialogue_Female_Scene4" -> Vox/Voice/Dialogue
• "GunShot" -> SFX
• "Menu_Theme_Variation" -> Music

If the assigned asset isn't descriptive or non-existing, try to look at the GameObject name or potential adjacent MonoBehaviour names. Ask to create an Uncategorized group if it seems hard or confidence is low in classifying how an Audio Source is being used.

Step 3: Agree the group list, and get any missing groups created

Present the classification from Step 2 as a proposed routing — each Audio Source and the group you intend to send it to — and revise it with the user.

WAIT for the user to respond before proceeding.

Prefer an existing group when it genuinely covers the category, even if you'd have named it differently. But don't collapse categories that a mixing engineer would keep apart — Foley is a subset of SFX, not another word for it, so a gunshot does not belong in a Foley group just because one exists. When the existing groups only partly cover your categories, say which ones fit and which need a new group, and let the user decide.

For categories with no matching group, you cannot create the group — there is no public API for it. Hand it over precisely, naming the mixer and the exact group names, as shown at the end of references/api.md. Then re-run the inventory snippet to confirm the groups exist and check their spelling before routing. Don't assume the user did it, and don't assume they spelled it the way you asked.

Step 4: Route the Audio Sources

With the group list settled and confirmed present, assign each Audio Source's output group using the routing snippet in references/api.md. It is public API throughout, and it wraps the whole pass in a single undo step so the user can back all of it out at once.

Key the mapping on the identifier you classified by. Step 2 reads the clip asset name first and only falls back to the GameObject name, so the mapping accepts either — the two are different identifiers and keying on the wrong one drops sources.

Three things to report rather than assume:

• Any NO SUCH GROUP entries the snippet returns. That means a group you expected is not in the mixer — usually a spelling difference. Resolve it with the user, don't silently skip the source.
• Any NOT IN THE MAPPING entries. Those are Audio Sources your classification missed. Reporting a successful routing while sources were quietly left unrouted is the worst outcome here, because it reads as success.
• The scene was modified, not the mixer asset. Routing lives on the Audio Source, so it only persists once the scene is saved. Tell the user, and save only with their agreement.

Volume, effects, and re-parenting are out of scope. Those live on non-public API. If the user asks for them, say the routing is done and point them at the Audio Mixer window for the mix itself.

References

See references/api.md