The Broadcast Bridge: What types of production environments benefit the most from AES67-compatible audio networking?

Greg Shay: There are two broad categories. In a live broadcast facility, the ability to have hundreds or even thousands of channels of audio, all available everywhere in that plant, instantly, without the large cost of a centralized matrix router. This was the solution first filled by Livewire AoIP and now AES67.

The second category is the wide range ability to connect professional audio wherever it is needed, independent of location. Geography doesn’t matter. In the same way we have come to expect our phones, and information on the World Wide Web to work.

I happen to believe for the first category, AoIP was a superior solution to a known problem. For the second category, AES67 AoIP using SIP unicast mode opens possibilities to change our workflows and gives new possibilities we have not even considered doing as of yet.

The Broadcast Bridge: What’s the challenge of implementing an audio network into an existing production environment?

Shay: Since most production environments are already thoroughly computerized, networks and an IT infrastructure are most likely already present. The choice a user has is to understand the demands of the audio networking and configure or upgrade the existing IT infrastructure, or install a new more capable network.

Audio networking does not necessarily require an audio-only separate network, even though many choose to do this. A properly configured converged network can be effectively shared between audio, other media and other duties, many do. What is not possible is to expect flawless audio network operation on an existing network, shall we politely say, cleverly patched together!

A good, solid managed IT infrastructure is required, configured for quality of service (QOS) and multicast routing (IGMP).

There are many other reasons that demand a solid IT infrastructure, and the attention of capable IT personnel, so this often is not too much of a challenge.

The Broadcast Bridge: AES67 was developed for audio over IP applications but it also benefits audio over Ethernet infrastructures. Explain how.

Shay: Ethernet is the physical network we are most used to plugging our cable jacks into. Ethernet does a great job connecting equipment together on the local area network (LAN). However, once you move to applications connecting outside the building, between cities, and around the globe (such as the world wide web), Ethernet needs to be ‘helped along’ or augmented by the use of internet protocol (IP). Ethernet is the wire that connects and carries the IP network information, but IP is really just a larger and more extendable way of addressing a wider reach.

Think of Ethernet as your house number, but IP as your zip code and country code. To reach long distances, you need a coordinated system using a whole address that has global reach, more than your private address. That’s what IP adds.

Audio over Ethernet (which there historically were multiple technologies for) was limited to the local network, in the building, and could not make wide-ranging connections.

Audio over IP has that reach, the ability to connect outside the building, between cities, and globally, all the wide-ranging connections that we have come to expect from using the web and not caring physically where a site actually is located.   

It’s also worth noting that in today’s modern building networks, IP capabilities are regularly used ‘inside the building’ to help segregate a single, building-wide physical network infrastructure in to multiple logical networks for either different purposes (internet, servers, AV, security) or physical locations (main building, annex A, B and C) or by department (users, technicians, security, etc.). In these cases, the use of IP capable technologies offer the ability to traverse the whole building network without requiring legacy network deployment techniques to be used as would be the case should the solution only support Ethernet and not IP technology.

The Broadcast Bridge: The standard also provides interoperability with layer 2 technologies, like Audio Video Bridging (AVB). Explain the difference between layer-2 and layer-3 protocol technologies.

Shay: Layer 2 means Ethernet, and layer 3 means IP. Please see the previous answer for the wide range of answers addressing the connection ability that Layer 3 IP adds.

AVB was a great idea with special features added to Ethernet layer 2, ideally suited to make carrying audio and video without dropouts easier. However, AVB suffered from two issues: it required specially designed Ethernet switches (which are not commonly available and are often more expensive than their non-AVB counterparts), and it suffers from the inability to have the wide range reach of layer 3, IP.

Fast-forward to the present, and the entire world of technology, IT, the worldwide web, global networks are all IP layer 3, with exponentially growing speeds. It makes more sense to harness the IP networks directly and gain all the advantages of connectivity. And this is exactly why AoIP was invented, and why AES67 is audio over IP.

Having said that, there have been some demonstrations carrying AES67 over an AVB link. This certainly is possible and allows the AES67 formatted audio content to take advantage of the improved timing and automatic traffic shaping capabilities inherent with AVB (layer 2 can carry layer 3), but AES67 doesn’t need AVB. At the end what comes out is still AES67 formatted audio. Note that this proof of concept has not yet made it in to any shipping products that we are aware of.

The Broadcast Bridge: Prior to AES67 standardization, there were (and still are) a number of AoIP schemes developed by various manufacturers and tech vendors. Why was the standard developed in the first place?

Shay: Customers like standards. Vendors like monopolies (that they can own and control) but results in a fractured market. At a key point in the history of AoIP (around 2008), enough of the leading vendors combined their momentum to establish a standard for AoIP in order to create a much larger, standard market. It’s the old IBM PC model of an open standard stimulating the industry, resulting in a ‘bigger pie’ from which all vendors (and customers) benefit in the end.   

Steve Church, late founder of Telos, approached Kevin Gross, the inventor of Cobranet, the first successful audio over Ethernet technology, to get the ball rolling within the Audio Engineering Society on an AoIP standard. Other vendors jumped on-board and the rest is AES67 history.

The Broadcast Bridge: Dante is a part of the AES67 standard. How are the two different? How do they work together?

Shay: Strictly speaking, the Dante technology is not part of AES67, but Audinate (the company behind Dante), in reaction to customer demand, has chosen to implement an AES67 mode as part of their interfaces.

The particular way audio data is packed into the network IP data packets is similar but subtly different between native Dante and AES67, as an example. AES67 is entirely open technology, and based on prior, proven standards, nothing was proprietary or newly invented for AES67. For the audio data packing, for instance, AES67 uses Real Time Protocol (RTP) audio streams, which came from Voice Over IP phone calls, from the early 1990’s. It’s a good example of AES67 reusing existing, trusted and proven technology.

A key point, AES67 includes ‘unicast SIP’ mode, which is fundamental to making connections over the wide area network (WAN) outside the building, connectivity independent of location. It enables the singer in Seattle to be recorded in Nashville (for instance), without getting on a plane. This vision of using AES67 as the wide range, studio quality, audio connection, is a genuine innovation in AES67, and was not in any of the prior AoIP technologies (Livewire, Ravenna, Dante or Wheatnet). AES67 took the opportunity to move the ball, and the industry, forward.

There are also differences in that AES67 is a standard for the audio streams and audio connections, but leaves certain choices flexible and open (for control and advertising what audio is around, for example). AES67 is more future proof, adaptable to what the workflow and application need them to be. Vendor proprietary AoIP can be more of a whole top-to-bottom solution including a control application you need to run, but as such is more closed-ended bound and limited to its use cases.

An example of this can be seen in last year’s adoption of AES67 as the ‘audio part’ of the new SMPTE 2110 set of video, audio and metadata over IP for the coming generation of TV broadcast and production ‘facility over IP’. The flexibility and openness of AES67 allowed it to be adopted into the TV infrastructure larger than its own audio domain.

The Broadcast Bridge: It appears there are less AES67-compliant devices (than say, DANTE) in the market. Why is this?

Shay: I would hazard a guess that what you are observing is the difference between a strong motivated sales and marketing effort, and a worldwide collaboration between engineers and companies supporting that collaboration. (Actually, if you count Dante devices as having AES67, then there are more AES67 devices when you add everyone else too.) I personally welcome the embrace of AES67 by the makers of Dante, and applaud them serving their customers and users that way. If they continue and become the largest supplier of AES67 technology and solutions, I say “good job!”

The Broadcast Bridge: Are AES67 infrastructures more difficult to install and operate?

Shay: My answer is with reference to a classic audio facility installation. Far and away, drawing on the know-how of IT professionals for set up and configuration, and given the remarkable reduction in cables, AoIP AES67 infrastructures are much easier to install and operate. The only hurdle has been the changeover for the classic soldering iron and XLR cable audio engineer, to the IT professional. This is pervasive in our modern world, and AES67 lets you tap into this megatrend and benefit from it.

The Broadcast Bridge: In terms of file transport performance and other technical attributes, how does AES67 compare to other networking protocols in the market?

Shay: Boy, this question waves the red cape in front of my inner nerd, but I have a simple yet real answer. The simple answer is that AES67 is completely similar to other standard networking protocols, cut from exactly the same cloth. There is no “gee-whiz-way-out-network- rocket-science” in AES67; it’s almost a let down!

But this was done intentionally on purpose. The ground rules for the AES67 creation committee were that we could only use known, proven, protocols, to ensure success and prevent blue-sky hypothetical things that in the end would not work (or require special network switches). They all had to be standards, all low risk, and all well known.

AES67, at its core, uses RTP, which is the exact same as Voice over IP, which has been around for over 25 years. In fact a good way to think about AES67, is as a “studio quality phone call.” It’s as easy to connect as dialling your phone, with full professional digital audio quality.

The Broadcast Bridge: It's been said that AES67 allows individual items to be connected to a network that primarily uses one protocol. What if a facility is using more than one?

Shay: AES67 is the common meeting ground, for a facility using more than one AoIP vendor or protocol. In other words, as long as you buy vendor equipment that is either AES67 compliant (like our Livewire+AES67 equipment, pardon the plug!), or has an AES67 mode alongside a vendor proprietary mode, you can interconnect using AES67. Making a big investment in equipment that operates only in a vendor proprietary mode is the big risk and what you want to avoid.

The Broadcast Bridge: Manufacturers need a standard to build to, correct? Did the lack of an open standard like AES67 prior to 2013 inhibit product development? Now that AES67 is a standard, is product development advancing faster?

Shay: To answer the last part of the question first, yes! AES67 AoIP products are coming to market much faster now than ever before. AES67 interfaces on all sorts of audio gear are springing up all over, mixing boards, processors, amplifiers, editors, workstations, interfaces to you-name-it prior types of audio interfaces (MADI, AES3, analog), even including microphones and speakers.

While AoIP was proprietary, a vendor of a new audio gadget had to choose and commit into which AoIP type to build for. Now that barrier is taken away and all good ideas can come to market with AES67.

The Broadcast Bridge: What’s the future for AES67? What yet-to-emerge new networking architectures will it facilitate?

Shay: What a great question at the end, to let the future potential of AES67 be heard! Yes, from the conception of audio over IP, (which in my own personal case was in 1996 in a conversation with Steve Church, late founder of Telos) the intent was to hitch our audio wagon to the billions spend on R&D by the giants of the information technology (IT) world.

This is the real key to the vision behind AoIP, and its standardization in AES67. By not inventing something off to the side specific for an audio network, by sticking to standard IT networking technology, and figuring out how to get the audio job done using standard IT equipment, we then get to take advantage of all the future growth of the IT industry. That’s a hell of a thing.

Fiber optics is no problem. 100Gbps, no problem! Future IT networking technology not even invented yet… yes we can plan to use. The IT industry has great inertia; they can’t break their own fundamentals. By getting on board those fundamentals, we are along for the ride. And AES67 puts professional audio on that train.

Some of the most exciting future potentials I have already seen the first demonstrations of, are remote performance and remote production, without any compromise of quality. I saw a string quartet, split two and two between San Diego and San Francisco, play in perfect coordination over a low latency audio over IP link. I can imagine a future where a producer walks into a recording facility, sends a .vcf contact to the console with the ‘sip:[email protected]’ contact for the talent in his home studio, pushes the button and go! At the professional level, there is no time to record and swap files.

It is about people, and performance, in concert together, collaborating as if in the same room. Since the invention of Bell, we have had the ability to reach out and touch with what we all grew up with as ‘phony’ sounding audio. Now with AES67 we will be able to have full professional quality audio with the same convenience and touch.