AV over IP

AV over IP (SVSI)

The AVoIP system distributes video around the building over standard Ethernet using AMX SVSI (NMX) encoders and decoders, instead of a matrix switch and dedicated video cabling. An encoder turns an HDMI source into a multicast stream; any decoder that subscribes to that stream shows the source, so switching a destination is just changing which multicast group a decoder listens to.

The fleet is AMX N-series Gen 2 — 53 endpoints as of 2026-09-18, in five models: N1122A (12) and N1115A (7) encoders (SVSI_TXGEN2), N1222A (30) and N1233A (1) decoders (SVSI_RXGEN2), and 3 × N432A audio transceivers. Every signage TV — and the Atrium and Legato projectors — has an N1222A decoder behind it. The full live inventory is on the network map.

Network

  • VLAN 25, subnet 10.0.25.0/24, DHCP from the EdgeRouter, authoritative. See Networks.
  • AVoIP Switch — a Cisco SG-500X (10.0.25.207), in the AV room left rack (green cabling). It only assigns the AVoIP VLAN but trunks the others.
  • The VLAN is extended across the AV M4250s (Core, Stage, Control Room, M21, Atrium) so decoders can live behind any TV in the building.
  • The signage distribution end lives in the server room: the AVoIP-DS M4250, the DS source encoders (in SVSI sleds), the DS playback PCs, and a RackLink that powers the PCs and sleds — laid out port by port on the network map.
  • Video multicast; each endpoint’s getStatus (TCP 50002) reports its name, subscribed stream, DVI status and input resolution — that’s how the network map is built. SVSI audio can also ride AES67.

How signage flows

The digital-signage source PCs (in the server room) feed N1122A encoders named DS1 – General Slides, DS2 – Kids Min, DS3 – SCS and Digital Signage 4. Those streams are subscribed to by the N1222A decoders behind each TV around the building — Atrium, Legato, Kids Min, Green Room, Balcony, Treehouse Preschool, SCS, and more. Room-facing displays and the Atrium/Legato projectors are all just decoders picking a stream.

Notes

  • A decoder shows black when its source encoder isn’t producing a picture (e.g. a signage PC sitting at a login screen). The source, not the decoder, is usually at fault.
  • Decoders run in auto or a fixed mode (e.g. 1080p60) with optional scaler bypass; a resolution/scaling mismatch is a common cause of a blank output. Encoders have the same setting, and it changes what every subscriber gets: an encoder with its scaler engaged streams at its output mode, not its input. The signage encoders all bypass it.
  • “Legato” and “Atrium” are rooms/spaces, not devices.

Where the config lives

Switch configs under Networking/ (AVoIP Switch, AVoIP DS Switch) and the EdgeRouter reservations in Networking/Router/. The SVSI endpoint config lives on the devices themselves (read live via getStatus). Changes are logged in the AVoIP changelog.