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Media Link

What happens after MIDI? The question has often been asked but never answered. Scott "Compatibility" Wilkinson looks into a system that incorporates MIDI and a whole lot more.


MEDIALINK COULD DO FOR MIDI, SMPTE, VIDEO, AND AUDIO SYSTEMS WHAT MIDI DID FOR MUSICAL INSTRUMENTS. HERE'S A PEEK AT WHAT MAY WELL BE THE FUTURE OF MEDIA SYSTEM INTEGRATION.

WHEN YOU STOP and think about it, the very existence of MIDI is astonishing. With unprecedented co-operation between competing synth manufacturers, MIDI equipment can be connected and used together - at last. Although the first use of MIDI was merely playing one synthesiser from another keyboard, creatlve minds everywhere soon expanded its application and large, integrated music systems began to appear.

As musicians were incorporating MIDI into their activities, other media systems were also being developed. The world of film and video had been using SMPTE for synchronising dialogue and sound effects to picture for some time. Digital audio was born with the promise of superior fidelity, microscopic editing and no generational loss. However, although these systems have been integrated to a certain degree (particularly SMPTE and MIDI), they have remained essentially separate entities with little that they can actually say to each other.

All these developments have one thing in common: they all require a relatively high degree of technical sophistication of their users. This requirement leads many musicians into a quandary. They find that complex technology, which was developed to help them be more productive, actually ends up inhibiting their creativity. It's hard to be spontaneous when you have to look for the cause of a stuck note or the reason why a synth isn't responding. Of course, this isn't true of all musicians. But for others, technology throws cold water on the creative spark.

Enter MediaLink. Like MIDI, MediaLink defines hardware and software protocols that third party manufacturers can implement in their equipment. While MIDI was developed specifically for electronic musical instruments, MediaLink is designed to carry simultaneous signals from any digital media system, including MIDI, digital audio, and SMPTE with equal ease.

MediaLink is the brainchild of two Americans, Mark Lacas and David Warman. Both are avid musicians who have been working in the computer network and data communications industries for the last ten years. MediaLink was inspired by a desire to simplify their life in the MIDI studio.

Lacas explains: "We were having trouble making an album over the last couple of years because of all the technology getting in the way. The technology was necessary because of the complexity of the musical arrangements, but was too distracting to deal with when I was in creative mode."

Lacas and Warman formed their own company, Lone Wolf Inc. in order to develop an entirely integrated, transparent system with which musicians, film-makers and other media artists can concentrate on their craft without worrying about the supporting technology. While this is a worthy goal sought by many in the past, it has rarely if ever been fully achieved.

THE VISION



THE DEVELOPMENT OF MediaLink is driven by a simple vision ("One button, one cables"). Of course, the simpler the vision, the more complex the underlying processes that support it. MediaLink is no exception. Even so, Lacas guarantees that "the end user will be entirely shielded from everything that we do."

Of course, no technology yet developed can read minds. So part of the Lone Wolf philosophy became "Everything that can be configured, must be - no more than once." Lacas continues this train of thought, "Rembrandt didn't mind painting a picture once, but he'd never go back and do it again. In fact, electronics have allowed us to approach music more like an artist approaches a canvas. We can go back and paint over sections that we don't like. But we want to do the whole thing only once. Then we want to capture the essence of what it took to get there, all the aspects involved in making it what it is. To get there a second time should involve pushing one button at most.

Lacas and Warman have spent a lot of time considering the way in which musicians and other artists operate. One conclusion that they have come to is that creative people tend to prefer names over numbers. So songs, equipment configurations, and individual devices will be addressable by user-defined names in Lone Wolf MediaLink devices. As an alternative, they can also be numbered by the user and addressed in that way if so desired.

THE AWARENESS



FOR LONE WOLF, the goal is to run a single cable that will connect all parts of a system. All of the information handled by the system will be directed along this cable in any direction (this is called bidirectionality because a signal can flow in either one of two directions within a single cable). A MediaLink compatible device will require only a single connector and cable to tap into the network - no MediaLink In and Out. Lone Wolf devices will include two functionally identical connectors to facilitate buss and ring topologies, but it won't matter which one you use.

For a device to be "MediaLink aware it must contain a piece of software code called an agent. The agent stores a template of configurable data for a device - how many voices are available, their MIDI channel and patch assignments, how to set all user-definable parameters, and any other data that a developer wants to include. When connected to a MediaLink network, the agent makes this information available to any device on the network that requests it. With the touch of a single button, the complete settings (not just the patch data) for every device in even the most complicated MIDI system become available and can be recorded into a sequencer or printed out to provide a hard copy record of a session. For the artist, pushing a single button will configure the whole system, including patches, signal routings, sequence selection, and every other aspect of the project at hand.

Figure 1. The four basic network topologies: ring, star, buss, and tree.


LAN BASICS



TO UNDERSTAND THE potential of MediaLink, it helps to know a little bit about computer networks. But don't worry, this is not as formidable as it may sound. You may even have heard the term "LAN" bandied about. LAN stands for Local Area Network, the most common means of connecting several personal computers together into a larger system. This allows users to share information and resources.



"PUSHING A SINGLE BUTTON WILL CONFIGURE THE WHOLE SYSTEM: PATCHES, SIGNAL ROUTINGS, SEQUENCE SELECTION, AND EVERY OTHER ASPECT OF THE PROJECT AT HAND."


One of the most basic aspects of any LAN is its physical configuration (how the individual members of the network are physically connected). This is called the "topology" of the network. There are four basic configurations: ring, star, buss and tree (see Figure 1 for a diagram of each type of topology).

In a ring topology, the members are connected to a closed loop of cable. A star network consists of a central hub (usually a governing computer) to which all the other members are attached. In a buss topology, each member taps into a cable that doesn't close on itself as a ring does. A tree network is an expanded version of the buss topology in which several buss networks are connected to a central "trunk" (called the backbone in LAN terminology), forming the "branches" of the tree. This topology is used in large buildings in which the backbone of the computer network runs up and down between floors with connected branches on each floor.

Another important aspect of LANs is their protocol. This is the way in which the network manages the flow of information from the "talkers" (members that send information into the network) to the "listeners" (members that receive information from the network). Again, there are four basic types of protocol: simplex, token, polling and CSMA (Carrier Sense Multiple Access). These protocols are often likened to human conversations.

As the name implies, a simplex system is the simplest protocol. (As you'll see, MIDI is an example of a simplex system.) Information flows in only one direction along a given cable and there is generally only one talker at a time. This is somewhat like a dictator who talks while his subjects listen without the ability to respond. In the token protocol, a specific message (called the token) is passed from one member of the network to the next, typically in a ring topology. If a member has the token, it is allowed to talk, sending information into the network. When it's finished talking, it passes the token to the next member. If that member has something to say, it takes the token, says its piece, and passes the token on.

The CSMA protocol is like using a party line or having an undirected conversation within a small group. When you hear a gap in the conversation you can jump in and talk. If two people jump in at the same time, whoever's idea is more important will probably be more persistent. That's how CSMA works. Each member of the network senses when another member is talking and jumps in if they have something to say when there is a lull in network activity. The AppleTalk protocol built into the Macintosh is an example of this scheme.

A polling protocol is generally implemented in a star network. In this protocol, a central computer directs the "conversation" on the network, telling the members when they can talk. If the central computer goes down, the network grinds to a halt. This system works like a large meeting directed by a chairman.

THE MIDI LAN



IF YOU HAVE two MIDI devices connected together, you have established a simplex LAN. MIDI systems use the simplex protocol in which information flows along a given cable in only one direction. This is why a separate cable is required for MIDI In and Out. There is generally one talker (typically the mother keyboard or sequencer) and several listeners. You can manually specify which component is the talker by switching cables or changing the connections in a MIDI patchbay. Of course, a MIDI merger allows more than one device to talk at the same time, but this is quite limited, typically allowing no more than two instruments to talk simultaneously. Daisy-chaining MIDI devices together with their Thru ports forms a buss topology. Using a MIDI patchbay or Thru box forms a star topology.

Even with its inherent benefits, the MIDI LAN has become the subject of some controversy in the world of music. As MIDI systems grew larger and more complicated, many people began to complain about the speed of MIDI, delayed signals and the limitations of 16 channels. In addition, MIDI began to be used in applications never envisaged by its designers. It's currently being pushed to the limit, even though there's plenty of room in the MIDI spec for expansion and definition of new messages.

It must be said that many of these complaints are unwarranted. For example, MIDI rarely causes perceptible delays. Delays are usually a result of the time it takes for an instrument's microprocessor to deal with incoming MIDI data.

As with all systems, there's a limit to the amount of information that MIDI can handle. At a data transmission rate (Or bandwidth) of 31,250 bits per second, no more than about 500 Note On/Off events per second can be sent down a MIDI cable. However, the practical note limit is much smaller than this, due to the presence of other performance data such as pitchbend or aftertouch. This can lead to delays in massive synthesiser orchestrations with many notes and other continuous controllers, particularly when multitimbral sound modules are used.

In the beginning, 16 MIDI channels seemed plenty, but MIDI systems grew to be quite large and the capabilities of instruments improved. These days, just two multitimbral synths can use up all 16 channels. This limitation can be overcome by using several independent MIDI systems being controlled by a computer with multiple MIDI Ins and Outs. A MIDI interface with four sets of MIDI ports can control a system of up to 64 separate channels. But this doesn't provide a true 64-channel system; it's four 16-channel systems tied to a common computer in a sort of star/tree topology. MIDI does what it's supposed to do and is likely to be in use for a long time to come. However, in order for MIDI to expand far beyond its current boundaries and interface seamlessly with other media systems, a protocol like MediaLink is necessary.

MEDIALINK LAN



IT WAS OUT of frustration and the limitations of MIDI systems that MediaLink was born. Its purpose is not to replace MIDI, SMPTE or any other media system. Rather, it was conceived to connect these systems together and provide a level of integration and transparency that has up until now been unavailable.



"OTHER THAN COMPLETELY CONFIGURING A SYSTEM, THE MOST OBVIOUS APPLICATION OF THE MIDITAP IS THE EXPANSION OF MIDI SYSTEMS INTO MUCH LARGER ENTITIES."


One of the hallmarks of MediaLink is its flexibility. It can be run on a ring, star, buss or tree topology. It uses a hybrid protocol that combines the best aspects of token, polling and CSMA. While virtually all other networks use copper wires in their cables, MediaLink uses fibre optics. Aside from allowing a much higher bandwidth than copper wire, fibre optic cable has the advantage of being impervious to stray electromagnetic fields and other noise. The cost of this cabling has started to drop dramatically as well.

The MediaLink bandwidth can vary from 1 Megabit per second (Mb/s) to 100 Mb/s. Even at its lowest bandwidth, MediaLink can accommodate 30 times the amount of data that MIDI can (with its bandwidth of 0.03125 Mb/s). At its highest bandwidth, this factor jumps to 3000 times the amount of information that MIDI can handle. The bandwidth also depends on the devices in the system. No device yet devised can run at 100 Mb/s. However, MediaLink is capable of running at this bandwidth in order to accommodate such devices as they become available in the future.

The MediaLink specification defines over 65,000 "groups" that are analogous to MIDI channels, although each one can carry a fully loaded MIDI data stream on all 16 channels simultaneously. Each group can include any number of devices and media systems that will respond to messages intended for that group. In addition, each group can include any number of talkers, unlike MIDI. Of these groups, half are user-definable. The other half are manufacturer-specific and addressed with a manufacturer ID number.

MediaLink messages are called "datagrams." These are packets of information much like MIDI messages. In fact, MIDIgrams are a specific example of MediaLInk datagrams. These messages can Include any valid MIDI message. Other datagrams include SMPTEgrams, videograms, audiograms, and so on.

Enough about MediaLink itself, what about its applications? As mentioned in the introduction of this article, one of the primary applications of MediaLink is the integration of various media systems. For example, a MIDI system, video system, digital audio system, and lighting system could be connected together and send each of their respective types of data along a single cable. In live performance, this would mean a single cable running from the stage to the mix island, from which the sound, visuals and lights are all controlled in an integrated fashion. In a professional studio environment, a single cable could connect the control room with systems located throughout an entire complex. Any device in the facility, regardless of which system it's physically connected to, can be accessed from any other system in the studio. Instant reconfiguration is possible without moving or repatching a thing. With network management software already under development for Macintosh and PC compatible computers, the possibilities seem virtually endless.

THE MIDITAP



THE FIRST DEVICE to embody these concepts is the MIDITap from, strangely enough, Lone Wolf. This unit, which can run at bandwidths up to 2Mb/s, forms the interface between a MIDI system and MediaLink. With it, you can connect several separate MIDI systems and integrate them into one large but entirely manageable system.

The MIDITap includes four MIDI Ins, four MIDI Outs, an RS422/232 serial port for connection to a computer, and two MediaLink fibre optic connectors. Each MIDI port includes its own MediaLink agent which can be programmed with configuration data for any MIDI instrument. Imagine a new market for "plug-in software modules" preset with configuration data that can be downloaded to an agent, providing MediaLink compatibility for existing synths, which, of course, are non-MediaLink aware devices.

The MIDI ports are entirely independent and can be mapped in any way you wish, including full merging capabilities on all four inputs. They can also filter MIDI data in any way and send various MIDI messages in response to an incoming message. For example, if you select a program change on your master keyboard, the MIDITap can configure itself and any other device in the system in response to the program change. The serial port can be used to control the MIDITap with a computer or can be connected directly to a modem for communication with a remote system without using a computer at all.

The front panel of the MIDITap illustrates the user interface that will be common to all Lone Wolf devices. There are four buttons labelled Exit, Edit, Enter, and Command, a two-line LCD, and a parameter knob. The buttons provide access to any function in a series of menus. At the topmost level, the parameter knob scrolls through the menu choices. Pressing Enter takes you down into the selected menu. Whenever you reach a parameter that you wish to edit, press Edit and use the parameter knob to change the value. This knob is veIocity sensitive, so that the faster you turn it, the faster the value changes. After changing a parameter, pressing Enter registers the new value, while pressing Exit deletes the changed value. The Command button brings up context-sensitive commands at any menu level. The use of these buttons will be optional if you're using a computer to control the box.

The LCD serves several functions. It displays the parameters and their values as well as the names of the devices and configurations that you have defined. It can also indicate the level of MediaLink activity on the network and in the box itself with bar graph meters.

One of the best aspects of this device is the fact that you can control any MIDITap from any other in the system. The front panel is actually independent of the box to which it is attached. You can dial up the name of any device in the system on the front panel with the parameter knob, press Enter, and be in full control of that device. In addition, there's provision for future hardware modules to be added to MIDITap.

Apart from completely configuring a system with the touch of one button, the most evident application of the MIDITap is the expansion of MIDI systems into much larger entities. With full group and channel mapping, any MIDI message on any channel in any MediaLink group can be converted into any other message and sent to any other channel(s) in any other group(s). This eliminates the limitations of 16 channels and parallel MIDI systems. Merging and stacking are rendered almost trivial. To merge, simply send data to the same group. To stack sounds, configure a port on the MIDITap to listen to the same group. Each MIDI port is fully independent and communicates with the other ports internally via the MediaLink protocol. Another interesting possibility is system reconfiguration. If you have created a piece of music in one MediaLink-equipped studio, you could take a disk with your musical data and system configuration to another MediaLink-equipped studio. The computer would then modify your configuration to match the new studio or modify the studio's configuration to match your music.

THE FUTURE



LONE WOLF'S PLANNED developments include taps into other media systems such as SMPTETaps, VideoTaps, AudioTaps, and even SCSITaps. With them, media systems will be integrated and controllable like never before. The Lone Wolf vision could well represent a bold step towards a future in which technology won't inhibit musicians and other media artists, but instead help them achieve their aims.

(Contact Details)



Previous Article in this issue

Microillusions Music-X

Next article in this issue

Casio VZ8M


Music Technology - Copyright: Music Maker Publications (UK), Future Publishing.

 

Music Technology - Oct 1989

Topic:

MIDI


Gear in this article:

Connectivity > Lone Wolf > MIDITap

Feature by Scott Wilkinson

Previous article in this issue:

> Microillusions Music-X

Next article in this issue:

> Casio VZ8M


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