Audio Over CAT5: Other approaches, Part II

Continued from 'Audio Over CAT5: Other approaches'….

IEEE-1394 is another common audio interconnect scheme, employed by TC Applied Technologies and its exclusive distributor, Wavefront Semiconductor, with their DICE-II chip, and in audio-enhanced form by companies such as MOTO (Audio Wire) and Yamaha (mLAN). Broadcom's Michael Johas Teener also points out that the IEEE-1394b and 1394c variants also specify CAT5-like 100m drive distance capabilities. However, in his mind, it won't be the dominant networking scheme, at least in residential environments.

“There is really only one difficulty in using 1394 as the backbone of an A/V network,” he writes. “1394 is not Ethernet. For almost all existing computer applications, the existing and planned wired network is (or will be) Ethernet. If a home already has a wired digital network, it is almost surely Ethernet; very few 1394 home networks are yet deployed. If a consumer buys a computer, it almost surely has an Ethernet port, while it only has a roughly 50% chance of having a 1394 port. So, although 1394 is a perfectly adequate (arguably, even superior) A/V interconnect, Ethernet’s market leadership makes it unlikely for 1394 to become the primary network in the home”.

Fibre Channel is yet another potential audio carrier, according to Great River Technology's Director of Marketing, Tim Keller. "FC-AV stands for Fibre Channel Audio Video and is a protocol that is growing in popularity for both commercial and military aerospace programs that use uncompressed, real-time digital video.FC-AV has been used for over 5 years by many to the larger OEMs and suppliers for connecting displays, cam-eras, sensors, and mission processors on a dedicated, point-to-point video bus.In the last several years, an of-ficial specification was adopted: ANSI INCITS 356-220. An ARINC committee is writing standard 818, called Avi-onics Digital Video Bus, and the current proposal draws heavily from the ANSI standard for FC-AV.Additionally, a high-speed version of MIL-STD-1760 is in develop-ment, and they have adopted FC-AV as the protocol for digital video. In a nutshell, both commercial and military standards covering high-speed digital video have adopted FC-AV".

USB 1.1's incomplete isochronous implementation and limited bandwidth restricted its use in quality- and latency-sensitive audio applications, particularly those requiring greater than two audio channel support or simultaneous playback and recording. USB2 made tangible improvements in these areas and is beginning to be widely adopted as a computer-to-peripheral interconnect scheme as it becomes pervasive in computers; see, for example, Edirol's UA-101 and UA-1000 audio recording and mixing devices. However, its limited 5m drive distance precludes its use in the types of audio distribution applications that this article highlights, unless it's supplemented by USB-to-CAT5 or USB-to-fiber optic bridge devices.