Audio Distribution and Control Using the IEEE 1394 Serial Bus

This paper describes a system for transmitting hundreds of channels of high quality digital audio, control & monitoring protocols, and digital video over an IEEE 1394 serial bus. The paper provides a brief tutorial on the IEEE 1394 standard, paying specific attention to digital audio formats and synchronization methodologies. Recommendations are made for the audio industry to standardize audio protocols above the IEEE 1394 standard to enable future interoperability between a variety of devices. Introduction The world needs a multichannel digital audio interconnect standard. The majority of today’s digital audio systems are connected using the AES3 and IEC958 (a.k.a. “AES/EBU” and “SPDIF”) interfaces. These standards were designed to carry a single stereo audio stream in a fixed point-to-point connection between two devices, and were optimized for the Red Book CD audio format. Each pair of audio channels must be transferred over an individual cable, adding significant cost and complexity to multichannel systems. Their asynchronous nature complicates the process of synchronizing multiple interfaces, generally requiring expensive sample rate conversion. Control information is typically passed along separate proprietary paths, such as MIDI (via System Exclusive commands), RS-232/422, or infrared transmission. These standards lack the data-carrying capacity and flexibility to support tomorrow’s sophisticated digital media systems comprised of multichannel digital audio, digital video, sophisticated control & monitoring protocols, and TCP/IP. Because of the inherent limitations of AES/EBU and SPDIF interfaces, developers of multichannel digital audio equipment have invented a number of proprietary interconnects for exchanging digital audio data between multiple devices. For example, the Alesis ADAT Optical