Understanding MIDI

MIDI stands for Musical Interface Digital Instrument.  It is used to connect devices such as MIDI controllers, sound modules and a PC together so they can send MIDI data back and forth, MIDI data consists of the values 0-127, 128 values in total.

midi-cable

MIDI data sends information such as the pitch of a note, the velocity of a note or any type of a parameter value of a virtual instrument such as filter cut off or modulation (via a modulation wheel on a MIDI controller).  It is important to understand that MIDI cannot send audio or any other type of data but MIDI data (0-127).

MIDI data is sent back and forth between each device using a usb, a fire wire cable or in some cases with older equipment a 5 pin din cable although most new equipment will still have a 5 pin din connection so it is still compatible with older keyboards and sound modules.

MIDI connection

There are three different types of ports a MIDI cable can go into, MIDI In, MIDI Out and MIDI Thru.  A MIDI In is used to receive MIDI data from another device; MIDI Out is to send MIDI data to another device and MIDI Thru just re sends the incoming data to another MIDI device.

MIDI channels

MIDI channels are important to consider if you are planning to use a different number of sound modules or controls in your setup.  Standard MIDI can use up to 16 different channels; this can be useful for controlling several parameters at the same time.

It is important to make sure to assign the MIDI channels between different devices, some devices will do this automatically, but some will not, and if you don’t assign them correctly the data will simply be ignored by the receiving device.

Connecting to a PC

When connecting a MIDI device to a computer you will have three options of doing so, as computers do not have direct MIDI ports you either need to use a usb cable, a MIDI to usb cable, or an interface with MIDI in connection(s) on it, this will then connect to a computer via usb.

For larger setups it is recommended to have an interface with multiple MIDI inputs & outputs, or simply get past this problem by using usb or MIDI to usb cables.

Using MIDI inside a PC

MIDI data is especially useful inside of a DAW application, using a MIDI controller or keyboard to trigger notes or record automation of a parameter inside the DAW or inside a VST (Virtual Studio Technology) just like on a hardware device.

The software equivalent also uses MIDI data 0-127, a piano roll inside a DAW will have 128 keys, and parameters such as note velocity, filter cut off and modulation will all be recorded at a scale of 0-127.