This chapter covers need to know basics about building a MIDI-Setup and the necessary hardware involved

MIDI Jacks

The visual interface of MIDI to the outside world is usually a trio of female 5-pin jacks (see this link for technical details) There are separate jacks for incoming MIDI signals (received from another instrument that is sending MIDI signals), and outgoing MIDI signals (i.e., MIDI signals that the instrument creates and sends to another device). The THRU port also sends data out to the MIDI system, but not in the same manner as the OUT port. The data coming from the THRU port is an exact copy of the data received at the synthesizer's IN port. There is no change made to the data from the time it arrives at the IN port to the time is leaves the THRU port (which is a very, VERY small amount of time).

PC to MIDI Connection

Controlling Visuals via MIDI is usually done by using different flavours of MIDI-Hardware controllers (you'll find some commonly used brands at hardware section at vjcentral) controlling a computer unit running a MIDI interface. There are a number of MIDI interface products for PCs. The most common types of MIDI interfaces for IBM compatibles are add-in cards that plug into an expansion slot on the PC bus, but there are also serial port MIDI interfaces (connects to a serial or joystick port on the PC) and parallel port MIDI interfaces (connects to the PC printer port). Nevertheless it's a better idea nowadays following the USB Route, cause these interfaces are more flexible switching computer platforms and are usually equipped with multiple I/O-Ports if u're willing to pay a small amount of money more than for a single port version (only 1 IN/OUT/TRHU Connector). Great for using multiple Midi-Hardware-Units controlling one computer-Unit. However, it's possible to achieve the same effect using a midi-merger unit like the Phil Rees MIDI Merge Units

Connecting MIDI-Devices

You use MIDI cables (with male DIN connectors) to connect the MIDI jacks of various devices together, so that those instruments can pass MIDI signals to each other. You connect the MIDI OUT of one unit to the MIDI IN of another instrument, and vice versa. Many devices may be chained together using a series of single links to connect the units. In this case, the OUT of the first unit is connected to the second, the THRU of the second is connected to the IN of a third, and so on. Using this connection method it's possible to route midi-events from one MIDI-controller to multiple other units (e.g. controlling an computer and a midi-sound module or multiple computer at the same time). Sending the right midi controller codes still requires some basic knowledge of the midi protocol and will be covered in the next part of the Workshop entitled The MIDI Protocol: Messages and Events under Control.