BlackMatrix

An ATEM has no single thing called a router, so this treats every bus that takes one source at a time as a destination: the aux outputs, program and preview per ME, upstream and downstream keyer fill and key, every SuperSource box plus art fill and key, and every multiviewer window. On a Mini Extreme ISO that is 29 sources by 39 destinations, across as many switchers as you point it at.

Which sources are legal on which destination is read off the switcher rather than from a per-model table — every input reports an availability mask, and the app draws illegal cells hatched and refuses them server-side. That is what stops an aux output being routed back onto an aux bus, or ME 1's own output onto ME 1, without anyone maintaining a compatibility matrix.

The second half is protocol emulation. Each switcher also gets a Videohub Ethernet Protocol v2.3 server, so a hardware router panel, Companion's Videohub surface or Blackmagic's own software can drive the crosspoints without knowing an ATEM is on the other end.

An ATEM already serves that protocol itself, on TCP 9990 — and read back to back the two agree on every destination they share. What Blackmagic's own server offers is five outputs: Output 1, Output 2, Webcam Out, Program and Preview. This offers the other thirty-four. Use the switcher's own if five is what you need.

The third half is redundancy. A failover watch polls a machine — a TCP port, a URL, or a heartbeat it must be sent — and fires an ordinary salvo when it stops answering, which is the whole safety argument: the failover is the same button an operator can press by hand, so it can be rehearsed before the show rather than discovered during it. It will not fire until it has seen the machine working once, it starts disarmed, and it does not switch back unless you say what back means. For rigs where the media server drives the router itself — disguise's understudy sends matrix routing on failover, PIXERA fires a control action at a matrix switcher — the Videohub emulation is the target, and there is a plain-text line protocol on TCP and UDP for everything that can send a string but not speak Videohub.

There is a browser simulator with a device library, a mock fleet of three deliberately different switchers for development, desktop builds that bundle their own Node runtime, a container, and native iOS and Android shells that find the server for you — neither of which has yet run on a physical device. A real Blackmagic Videohub can sit in the same fleet as a device rather than only as a client, so one grid spans both.