AES70: puzzling out a network control standard29 January 2016
In audio networking circles the continuing adoption of AES67 – the interoperability standard for IP audio networking technologies – was difficult to overlook during 2015. Audinate (Dante) and ALC NetworX (Ravenna) were among the technology developers to highlight compliance with the standard, while a 22-device demo at AES New York in October firmly underlined the impression that the standard is on course to be a fundamental part of audio networking’s future.
Simultaneously, however, another piece of the networking jigsaw was about to fall into place as a new control standard passed through its final phases of development. Defining a scalable control protocol architecture for the control and monitoring of professional media networks, AES70 is the end-result of five years’ intensive work by the OCA (Open Control Architecture) Alliance.
Two of the prime movers behind the OCA Alliance – Ethan Wetzell, platform strategist at Bosch Communications Systems (pictured), and fellow Bosch staffer, senior scientist Jeff Berryman – confirm that the final standard is “about 95%” unchanged from the OCA architecture as it was submitted to the AES in late 2013. They attribute this relatively smooth journey not just to a well-defined set of goals at the start of the project, but also a more intangible – and unpredictable – quality.
“There was a remarkable level of agreement throughout the development of OCA; in fact, I have never seen so much consensus [during a project of this scale],” says Berryman. “There really was a kind of ‘group magic’ that went on.”
The primary objective of AES70/OCA is to enable the change and monitoring of all operating parameters of a network device, including the creation and deletion of signal paths, parameter adjustments for signal processing objects, network device firmware updates, and management of access control. In addition, control may be limited to facilitate simpler ‘operator’ functionality such as level, mute, power on/off and fault indication.
Operating on commodity Ethernet networking hardware or via standard 802.11 Wi-Fi, the control architecture may be used in conjunction with any available transport protocol, including Dante, AVB, CobraNet and AES67 – although it should be noted that AES70 does not itself provide a means of media transport or define the internal programming of a network device.
Whilst the OCA project has only assumed a high profile in the industry in the last couple of years, its roots run deep. OCA was based on a control protocol, OCP, which was developed by Bosch in 2009. In turn, that technology was informed by an embryonic control protocol standard referred to as AES24.
“A lot of time was spent ensuring that we were not reinventing the wheel” at the beginning of the project, says Wetzell, but it is clear that the stakes were much higher than for any other previous attempt at creating a control standard with mass appeal: “Everything that happens in this area is driven by evolution. When you had the original incarnation of audio transport over a network, the activity focused on getting a bunch of audio signals down a cable – it started and stopped there. But as systems have evolved, the concept of integration has become much more critical for a lot of people. You’re not just transporting audio back and forth anymore now – you are also sending data, intelligence and so forth.
“To support that you need [reliable] audio transport technologies and the means by which these devices can interoperate with each other. And that is where standards like AES67 – and now AES70 – come into the picture.”
Between 2011 and 2013, the members of the Alliance – initially totalling nine companies, including Bosch, but eventually rising to 15 – set about completing primary development of OCA. “It was more a case of refinement and fleshing out of details, rather than massive changes or additions,” says Wetzell.
The prospective standard was turned over to the AES in November 2013 – mere months after the publication of AES67 – for further fine-tuning. The standard public consultation process began in late 2015 and prompted no comments at all, paving the way for the publication of AES70 in the first few days of this year.
“It is not unusual for there to be no comments during the public consultation phase, but it is slightly out of the ordinary for a standard as big as this. I’d like to think that it is because it is very well-written!” says AES standards manager Mark Yonge.
As allowed by AES policy, the standard will be the subject of further amendments in the future. In the meantime, there will be substantial efforts to explain the benefits and practical implementation of AES70/OCA – not least at this month’s ISE show in Amsterdam. Among other features, a live demonstration on the OCA Alliance stand will show products from multiple manufacturers – including Bosch, d&b audiotechnik and Focusrite – operating with different network transport platforms under a single interoperable control system. Control will be provided simultaneously by OCA hardware, an iPad app and Chrome browser-based GUI.
Also on display will be OCA MicroDemo, a new compact and lightweight reference design that was developed between OCA Alliance member companies. This OCA implementation is designed to illustrate how OCA can be implemented efficiently in even the smallest devices, such as wall controllers and hardware designs where software and hardware resources are limited.
AES67 has taken a while to seep into the industry consciousness, and both Wetzell and Berryman agree that educational efforts around the latest standard will need to be extensive. “It’s very much an ongoing process, but we will be keen to emphasise the flexibility that [AES70/OCA] can provide,” says Wetzell. “It will provide a path for integration not just for [network] products, but also for the interaction of the products. The ultimate result will be a far better user experience.”
Process of discovery
Interest in AES70 is also likely to be fuelled by a proposed “certification tool” for compliant device development. “It won’t be a certification scheme along the lines of that established by the AVnu Alliance, but it will provide a programme that can be downloaded and run against the development of an OCA/AES70 device,” says Berryman, who points out that the process of ensuring that existing OCA devices – such as those using Bosch’s OMNEO media networking platform – “will just be the matter of a few days’ work at most, and often none at all.”
News of the completion of both transportation and control interoperability standards inevitably prompts the question: What about network discovery? Fortunately, work is already underway within the OCA Alliance to create what Berryman describes as a “directory standard. It’s the third piece of the puzzle and a very important one. I am hoping that we will have concrete proposals for the standard within about 18-20 months from now.”
Although each of these standards will be implementable in their own right, it is evident that a utopian vision of a comprehensive, fully standards-backed audio networking environment is at work here. “Absolutely, that is the plan,” confirms Wetzell, “and it might not be too far away now.”