1394 attributes and pro audio requirements
Realistically, the 1394 interconnect is the only viable solution for the scenario we've just reviewed. The reasons include bandwidth, topology, isochronous capability, timing information carried with the data, and peer-to-peer communications. It's also important that 1394 allows scalability via additional devices that musicians can add to the bus as required.
Professional audio requires significant bandwidth. The I/O boxes capture 24-bit data sampled at rates as fast as 96 kHz. The 1394 interconnect supports data rates as fast as 400 or 800 Mbps. And faster 1.6- and 3.2-Gbps versions are on the way. Generally, the 400-Mbps flavor affords the performance required in a professional audio application.
The story, however, goes well beyond bandwidth. The 1394 interconnect is inherently a peer-to-peer bus. Any device can initiate a data transfer to any other device or to multiple devices. The host PC does not have to be involved. In our concert scenario, the I/O box can transfer data directly to a mixer and the PC.
The 1394 interconnect guarantees QoS (quality of service) via its isochronous capabilities. Essentially, a 1394-based device can reserve the bandwidth it needs. Ad hoc traffic on the interconnect will not impact the real-time audio streams.
Timing information is also carried along with data on the 1394 interface. That timing information is critical for the producers mixing a recording back in the studio - allowing easy synchronization of multiple channels.
The scalability angle allows musicians to buy I/O boxes and mixers with the channels they presently require while knowing that they may need more channels later. It may also allow a band to carry less gear to a performance relative to what they need in a studio.
The 1394 interconnect supports almost any topology including most commonly a daisy chain of devices. That makes it easy to connect a PC, I/O box, and mixer. But device manufacturers such as Presonus also utilize that topology to offer an expandable system. For example, you can link two 16-channel mixers and realize a 32-channel mixer with the 1394 interface proving the real-time connection.
The peer-to-peer and synchronization capabilities also come into play in such daisy-chained scenarios. For example, the second mixer acts as a slave to the first. But the slave mixer can simultaneously transfer its output to the master mixer and the PC.