Audio over IP (AoIP)

Ravi Kiran Padmasolala, Manager, Technical - IMEA Bose Professional

Analog devices for professional audio applications was very popular for many years; audio engineers, system integrators and others in professional audio have developed a comfort level with these analog devices in their day to day activities like designing, installation, testing & commissioning, troubleshooting or any other support. Analog audio needs a separate physical circuit for each channel and routing of signals is inflexible. All of us have heard various terms in this pro audio industry like grounding, electromagnetic interference (EMI), radio frequency interference (RFI), signal loss, distortion, cable length limitations, etc. which were all the check points for ensuring good performance from a well-designed sound re-inforcement system in the analog domain. For years, system integrators had no option than to live with these limitations from analog systems. Let it be an auditorium or a large distributed audio network for PA-BGM, system integrators always had a tough time in identifying the right cable, cable lengths and laying cables without getting effected by EMI or RFI. Audio signal cables, microphone cables, speaker cables and electrical cables (for DC and AC power) of right choice was one of the main criteria for delivering good sound. System integrators have to work with many makes of audio interfaces to deliver the right sound reinforcement system, and every connection between two makes of audio interfaces is always a challenge due to difference in signal sensitivities and drop in signal levels.

Digital audio has an advantage of sending multiple channels of audio on a single physical circuit, but like analog audio is also inflexible in routing when relocation of equipment happens. Networked audio gives this flexibility of communicating with any device on the network irrespective of the device location / changes in physical location. Information technology, as all of us know has advanced to such a level where “Internet of Things” has become very common. Data exchange among devices has become very easy and super-fast. Analog audio though still popular has started looking towards digital due to various benefits over analog. Many proprietary digital audio networking devices and protocols have emerged to support Audio over IP and replace various analog devices. Audio over IP has overcome many of the limitations of analog signal transmission / distribution, like signal drop, EMI, RFI and also replaced bunch of cables with one single in-expensive cat5e cable. CobraNet was one protocol available for AoIP which supported digital audio networking for years but had some limitations like latency, compatibility or interoperability.

Many digital audio interfaces have been in the market to meet specific requirements, and some of the interfaces like ADAT, AES3, and SPDIF are well known in the industry. For digital audio over Ethernet, the common protocols used are Layer 1, 2 or 3:

Layer 1 protocols use Ethernet cables and switches but primarily employ proprietary media access control instead of the native Ethernet MAC. Examples include Riedel RockNet, Aviom A-Net, and Roland Pro A/V REAC.

Layer 2 protocols process audio by using the standard Ethernet packet approach. Two of the most well-known digital transfer approaches, CobraNet and EtherSound, use Layer 2, and it’s been adopted by numerous manufacturers.

Layer 3 protocols use IP packets for transmitting audio data over Ethernet cables. QSC Q-LAN, Axia Livewire, and Audinate Dante are a few of the transfer approaches that use Layer 3.

Recently we have seen Dante becoming popular in the digital network domain overcoming the limitations of earlier AoIP protocols available, with very low latency and excellent interoperability and supporting over 1000 channels of audio over a single in-expensive cat 5e cable. Today more than 300 manufactures have adopted this technology making the life of system integrators much easier in handling complex audio projects.

Bose Professional also adopted this technology quite early to meet the expectations of digital audio networking professionals with a huge range of products supporting Dante. Bose Professional has come up with Dante Endpoints which can convert most analog sources into Dante digital network signals. These Endpoints are small, convenient, cost-effective with Power over Ethernet (PoE) and Bose custom software allows them to be fully integrated and controlled with other Dante devices.

Bose Engineered Sound Processors (ESP) supporting various input output configurations and flexibility of controlling and getting controlled by third party controllers available in the market, through RS232 and serial commands over Ethernet, support Dante. Bose also came up with Dante enabled Under Table Boxes (UTB) for digital conferencing systems.

The ControlSpace EX Conferencing solution from Bose simplifies audio conferencing design and installation for large meeting areas by offering direct connection of Dante microphones, simple and elegant analog to Dante microphone convertors, interfaces for all types of audio conferencing, and time-saving algorithms.

Bose PowerMatch, multi-channel amplifiers are also Dante enabled with remote control and monitoring feature making the complete audio chain from source to speaker Dante compatible, supporting system integrators with complete package of digital networking devices. This product range gives system integrators the benefit of interacting with single OEM for the complete sound reinforcement solutions.

Further development in digital audio is from the Audio Engineering Society (AES), which came up with an open standard for Audio over IP (AoIP), AES67. AES67 is a standard to enable high-performance audio-over-IP streaming interoperability between the various IP based audio networking products currently available, based on existing standards such as Dante, Livewire, Q-LAN and Ravenna. It is not a new technology but a bridging compliance mode common to all IP-Networks; an interoperability mode you can put an AES67 compliant device into, on any participating network. AES67 operates over standard layer 3 Ethernet networks and, as such, is routable and fully scalable. AES67 does not eliminate existing networking systems but allows manufactures to build bridges between systems by also implementing the AES67 interoperability mode. Audinate has released AES67 support for the Brooklyn II module to Dante licensees. Products utilizing the Brooklyn II module will support AES67 once the product manufacturer releases product containing the required Audinate firmware, or releases an AES67 firmware update for existing products. Lot is happening on AoIP and we might see exciting technologies and products in this domain, in future.