---
id: edge-snapcast
area: edge
level: 3
title: "Artefact — Distributed audio · eight endpoints with ducking"
claim: "Eight synchronised endpoints with music ducked under every spoken announcement and restored afterwards — driven by Home Assistant and the voice assistant."
confidence: running
period: "2020–"
tech: [Snapcast, Mopidy, Spotify, Raspberry Pi, Home Assistant]
metrics: [{label: "audio endpoints", value: 8}, {label: "client hardware", value: "Pi 2W"}]
artefacts: []
public: true
last_verified: 2026-10-26
tags: [edge, audio, snapcast, artefact]
---

# Artefact — Distributed audio · eight endpoints with ducking

**Status: stub.** The topology diagram and a short recording of ducking land in Phase 7.

## What the artefact is

A Snapserver with eight Pi clients, Spotify and a local music server as sources, and one behaviour that matters more than the rest: when the house needs to speak, the music drops and the announcement plays everywhere, then the music returns to its previous level. Requests arrive by voice, so the same system that plays music is also the output for every automation and every answer.

## What it proves

Multi-room audio treated as infrastructure with a predictable interruption behaviour — and the difference between "the speakers work" and "the speakers can be interrupted safely". Mains-powered nodes, bandwidth-heavy work, and a state machine for volume: the opposite design constraints to the battery nodes.

## When it is delivered

Phase 7. Source: evidence notes section 1.