AXIA-LUFS

An EBU R128 loudness meter for Axia Livewire streams with a short-term (3 sec.) and/or momentary (100ms) loudness readouts. 100ms Resolution.

What is Axia Livewire?

Axia Livewire is an IP networked audio protocol used in broadcast. Among other things, it allows for 32767 channels of raw multicast PCM audio distributed over a standard IP network. Axia nodes are connected to the network and provide audio I/O.

What does a Livewire audio stream consist of?

Raw PCM (big endian, 24-bit signed, 48000 kHz, stereo interleaved) delivered in the form of multicast IP/UDP/RTP packets.

How does this work?

PCM from each packet is buffered and handed to libebur128 for loudness measurement.

To Do

Buffer input / confirm packet sequence. (UDP does not guarantee packets arrive in order; xNodes buffer 15-100ms the recieve side.)

Setup and Use

• Get libebur128, and then compile axialufs.c.
• Update index.js to point to the axialufs binary & supply an Axia multicast address.
• Lauch the node server: node index.js
• Visit localhost:3000 in your browser.