As audio production professionals continue to implement hybrid systems that incorporate equipment from a variety of vendors, the need for an industry-standard way to connect it all together to work seamlessly has been lacking for some time.
Recognizing this need for reliable interoperability, manufacturers of audio equipment for television broadcast and production are increasingly leveraging an already established AES standard protocol, called the Multichannel Audio Digital Interface (MADI) format, to help streamline the workflow of staff using audio consoles, digital audio workstations, audio signal routers and other products.
MADI is not a new format, but one that is now showing up more and more in new product offerings from makers of digital audio consoles, audio routers and digital intercom systems, allowing these devices to be easily interconnected. For users, interfacing directly to their digital audio streams through the MADI standard has become highly desirable.
“There have been many alternative multiple audio transports over Ethernet, each with a noncompatible and different propriety coding and encapsulation,” said Simon Browne, senior product manager at Clear-Com. The company is developing a MADI interface for its Eclipse Voice intercom system. “For some time the industry has been waiting for an emerging winning standard but this has not happened. This lack of an alternative standard built on IT techniques has kept the older and quite usable Audio Engineering Society-specified MADI standard alive.”
Indeed, apart from the advantage of shortening the workflow when an intercom is required to mix or route over audio consoles and station routers, the use of the single MADI cable or fiber to carry up to 64 channels of full audio bandwidth digital audio between devices saves significant time and effort during installation. The alternative might be to run 64 cables between an audio mixing console and its router ports.
In addition, keeping the audio in a recognized digital AES audio standard prevents degradation and allows user metadata to travel seamlessly along with the program and intercom material. The metadata might carry the source name label or normalized audio level so that intercoms and audio consoles can show the label on their user panel or fader displays automatically.
“MADI has always been a perfect solution for multichannel audio transport between devices of different manufacturers, since it was a standard and it transparently transported AES audio,” said Andreas Hilmer, director of marketing and communications for Riedel. “The reason why it’s becoming really popular now has nothing to do with changes in the MADI technology but with the trend of more integration between the various manufacturers and also technologies. Today it is quite common to integrate the intercom system with a digital audio router system, and with MADI as a standard, this can be easily established between various brands supporting this standard.”
Hilmer explained that if we take the integration between a digital intercom system and a digital audio router via MADI, for example, this allows us to route intercom panels, which are usually connected to the intercom matrix via an AES3/EBU signal, via the audio router environment and/or to transport broadcast-quality audio via the intercom system. This reduces infrastructure costs, because you don’t need to establish both infrastructures in every place.
Riedel’s MediorNet, a fiber-optic-based intercom system, offers built-in MADI interfacing as a standard feature. Hilmer said that the product might be primarily seen as a solution to transport video signals, but using the MADI format, users can combine their audio and intercom infrastructures into a single integrated backbone. The company’s Artist digital matrix intercom platform uses a dedicated MADI client card, while the Riedel RockNet digital audio network product line features a dedicated MADI interface device.
Niall Feldman, director of new products at Solid State Logic (SSL), said the newfound attraction of the MADI format is due to the ever-changing requirements of the broadcast industry.
“The move to 5.1 HD transmission has encouraged broadcasters to upgrade their production infrastructure, and moving to 5.1 audio production capability has been a part of that,” Feldman said. “Broadcasters have been upgrading from analog to digital audio consoles and looking for I/O, audio asset distribution and sharing solutions to accompany them. MADI is an open standard and as such it is a solution supported by a wide range of manufacturers, which for technical directors and systems integrators, makes combining technology from various manufacturers a simple, practical option.”
Among the benefits for broadcasters: MADI provides up to 64 channels of audio transmitted down a single optical cable for many miles without the need for repeaters; it is synchronous and has “near zero latency;” and it delivers fully transparent audio distribution without any degradation of the audio signal. In addition, MADI supports the remote control data protocols used by several manufacturers.
At the recent IBC Show, SSL showed its new MADI-X8 router that that takes full advantage of the MADI format. The router offers simple point-to-point bulk routing as well as source distribution (one source to many destinations), device splitting (any combination of individual channels to any destination) and source aggregation (a single 64-channel output consists of any combination of channels from various inputs). The MADI-X8 router also accommodates multiroom studio complexes that require real-time asset sharing and live sound.
NTP Technology, based in Denmark, also showed a MADI-compatible range of digital audio routing and processing equipment at IBC2010. The new NTP 625 MADI router features a 2048 x 2048 crosspoint matrix (in a 5RU frame) that can accept up to 18 MADI cards with four MADI input and output interfaces. Each frame has a TDM bus capacity of 2048 channels at 48kHz sampling rate, and two frames can be interconnected using the NTP XBus connection for a total of 3072 channels. The company’s QUAD MADI box can interface up to four bidirectional MADI connections on optical fiber or Cat 6 electrical cables.
Euphonix, now owned by Avid, offers its StudioHub MADI router, which can handle up to 12 MADI inputs and outputs (at 24-bit, 48kHz) and is used to connect various devices, such as audio consoles, digital audio workstations and signal processing modules. The StudioHub comes with a stand-alone PC program for making patches between the individual signal connections.
Until a more secure IT-friendly audio signal distribution format emerges, MADI will continue to provide a low-cost way to ensure equipment interoperability between devices from different manufacturers.
“As yet, no IP-based audio routing infrastructure has emerged as an open format, with each of the many IP-based solutions available today requiring installation of a proprietary network infrastructure,” said SSL’s Feldman. “Many broadcasters are somewhat reluctant to tie themselves to a proprietary solution and a single manufacturer.”
