Acronyms in the Ether
I’m a creative by nature. Computer science, math’s and physics don’t spark a flame in me and fill my daily cup with ‘joie de vivre’. However, there are times in my daily existence when acronyms such as IEEE-802.3, RJ45, AES67 and AOIP rear their monstrously academic heads and I’m expected to understand what they mean and how to apply them in my day-to-day life in studio.
Whether you identify as an audio producer, sound designer, or sound engineer, at the very core of your role is knowing how to get sound from point A-B without any quality degradation. In a world dominated by computers and the internet, networking audio devices has long since moved away from traditional analogue connections and has positioned itself squarely in the heart of computer science. The words ‘computer’ and ‘science’ may already offend the creatively spirited but bear with me for a minute while I simplify the most utilized audio networking process today and break down a few of the garbled acronyms associated there-with.
1. What is IEEE-802.3?
Simply put, it’s the recommendation standard (defined by some really smart people at the Institute of Electrical and Electronics Engineers) for which Ethernet is built upon. We use an Ethernet cable to link multiple devices in an audio network. Why? Because it transfers our precious audio data in a fast, secure, and reliable way. Radio interference? Nope. Ground hum? Nope. Transfer speeds of up to 100Gbits/s? Yip.
Most audio networks will adopt the use of twisted-pair copper-wired, Cat-5e or 6 ethernet cables with RJ45-8pin connectors. When your boss asks you to go out and buy new ethernet cables for the Focusrite Red Pre, go get the cat 5e or 6 version.
Side note* The different cable categories apply to their transmission speeds, whether cables are shielded or unshielded and their maximum bandwidth.
Twisted-pair, copper-wired Ethernet cable with RJ45-8pin connector
2. Audio Over Ethernet (AOE)
In AOE networks, we can physically connect devices via a Point to Point, Daisy Chain or Star topology. In audio, ‘topology’ is just a fancy word used to describe the structure and routing of your audio network.
A star topology is the most common type of ethernet topology found in an AOE networks today. It utilizes ethernet switches that allow for a smoother data transfer compared to a bus topology, where all the devices share the same path. Stars are pretty neat shapes huh?
Presonus AVB AOE Star Topology. Image courtesy of www.presonus.com
The trouble within the Ether…
When AOE networks first came into use, they were spread out as standalone networks between analogue devices. You could connect networks together through existing point to point analogue and digital connections but as AOE networks grew in popularity, they incorporated more audio infrastructure. The problem was that each time you needed to bridge a network to another, you would add more hardware, complexity, and cost. You would ultimately lose the advantage of what an audio network was intended to offer in the first place - namely, higher channel counts, more flexible signal routing and a consolidated clocking architecture. Enter AES67…
3. What is AES67?
Our academic friends at the Audio Engineering Society needed to solve a problem. As Audio networks were growing in popularity, the interoperability between different existing networks became an issue. How does a Ravenna based network talk to a Dante, Livewire or Q-Sys based network without costly additional hardware and excessively increased latency? AES67 was design to address these issues. It’s the standard that defines the requirements for high performance Audio-over-Internet-Protocol (AoIP) interoperability.
Why do we need to know about this? Whether you work in broadcast, live audio or a commercial production studio, by buying AES67 compliant products you know that, whoever those products are made by, they will be compatible and thus you will able to stream audio between them. This is one of those instances when reading the fine print could save you money and heartache. Check the compliance before splurging on a neat piece of gear you'd like to make use of in your network.
AES67 Interoperability. The 'compliance glue' that bridges AOE networks together.
To conclude, AOE networking is a vast topic and I could keep going to the depths of an academic acronym abyss with it all, but the chances are, the fundamentals that I’ve outlined above are enough to get you started in understanding the basic requirements for sending audio around an AoIP Ethernet based network, and how to build your own basic network.
What will your star topology look like? Well, thankfully that’s a creative decision. And it's left entirely up to you.