Square One: Into the Ether

Sep 1, 2008 12:00 PM, By Brian Smithers

           
 

HOW ETHERNET AND OSC IMPROVE ON MIDI

Musicians and engineers are always connecting one gadget to another, and as a result tend to develop a refined understanding of wiring standards, connectors, and, in the digital age, communication protocols. One such protocol, Ethernet, is showing up in an increasing number of audio devices. That fat telephone-style plug once used only for hooking up to a local area network is finding new and interesting uses.

The Lay of the LAN

Ethernet is the most common protocol for interconnecting devices on a network. It's a slight but useful oversimplification to say that the term refers to the RJ-45 (technically 8P8C) connector, Cat-5 cable, and packetized data format with which we're all familiar. Developed in the mid-1970s at Xerox, Ethernet offers speed, simplicity, and reliability. It also offers adaptability, as it is capable of carrying any sort of data, MIDI included. Although USB 2.0 and FireWire offer similar speed, availability, and flexibility, Ethernet allows longer cable runs.

Ethernet comes in three major types, defined by their bandwidth. 10Base-T offers 10 megabits per second of throughput, whereas 100Base-T and 1000Base-T offer 100 Mbps and 1,000 Mbps, respectively. 1000Base-T is also known as gigabit Ethernet. Ten-gigabit Ethernet is also defined, but it has not yet become commonplace. For comparison, FireWire 400 (IEEE-1394a) has a bandwidth of 400 Mbps, and USB 2.0 has a bandwidth of 480 Mbps.

It wasn't that long ago that conventional wisdom led the savvy DAW builder to remove any network devices from an audio computer. Since that time, however, network functionality has become ever more deeply integrated into the OS, and Ethernet ports have become ubiquitous on motherboards, including those in notebooks. Although one might still choose to keep a DAW disconnected from the Internet, local area networking has become an essential part of file and session management. Special servers can even allow streaming of audio and video assets across a network in real time.

Seizing Control

With a fast and proven data pipeline built into virtually every PC and Mac, it was inevitable that developers would start writing audio applications and creating devices to take advantage of it. Since the introduction of its first major control surface, the Pro Control, Digidesign has used Ethernet to exchange control gestures with Pro Tools. Even 10Base-T Ethernet, the stated minimum requirement for all Digidesign control surfaces, provides several times the 31.25-kilobaud bandwidth of MIDI, which is common in less expensive controllers.

This increased bandwidth allows the Pro Control, C|24, D-Control, and other Digidesign work surfaces to provide real-time metering, expansion to include dozens of faders, and reporting of track names and other information to the work surface. More speed allows more simultaneous control of level, pan, and plug-in parameters along with more-responsive writing of automation than is typical with MIDI controllers.

FIG. 1: The Euphonix MC Mix uses a protocol called EuCon to communicate with host applications via Ethernet more quickly and precisely than MIDI would allow.

Similarly, Euphonix takes advantage of Ethernet's speed in its control surfaces, including the MC Pro and System 5 MC. A special protocol called EuCon translates the control surface's gestures into messages that can be understood by various host DAWs and that provide greater resolution than MIDI. This same arrangement has also been implemented in the more affordable MC Mix (see Fig. 1) and MC Control.

Either-net

Ethernet is also being used extensively to move MIDI and digital audio signals between audio devices. Distributed audio-playback systems in convention centers, theme parks, and other large installations often use one of various networking protocols — Cirrus Logic's CobraNet or Digigram's EtherSound, to name just two — to deliver dozens of streams of high-quality digital audio from centralized servers to background music systems. Performance venues are using these same protocols to replace multicore analog cabling in sound-reinforcement systems.

Roland's REAC recording system lets audio signals be digitized onstage and sent via standard Ethernet to a PC running Cakewalk Sonar to be recorded. An audio interface is required on the PC only for confidence monitoring.

FIG. 2: This screen shot shows the configuration of a network MIDI port on a Mac. Since OS X 10.4, support for MIDI over LAN has been standard.

Various products allow MIDI control of soft synths and synchronization of DAWs over Ethernet. Apple's Mac OS X has had this capability built in since 10.4 (Tiger) was released (see Fig. 2). MusicLab's MIDIoverLAN CP extends this concept to include both Macs and PCs in any combination.

Digital audio connections such as S/PDIF and AES3 let audio be shared between DAWs, but they require some sort of audio interface. Plasq Wormhole2 offers an open-source cross-platform way to send a stream of audio from one machine to another and back through a 100Base-T or gigabit Ethernet connection for processing on the remote machine. FX-Max offers FX Teleport, a Windows-only application that off-loads the processing of a VST plug-in running on the host DAW to a remote computer.