5 important MIDI facts that's worth knowing
1 - MIDI Definition
MIDI stands for Musical Instrument Digital Interface. It is a digital communication language (a protocol) developed to send and receive music performance data to and from electronic musical instruments.
It is important though to note that MIDI does not transmit audio, so MIDI is NOT DIGITAL AUDIO!!
2 - MIDI Connections
The MIDI standard uses a DIN (Deutsches Industrie Norm) connector, with five pins distributed over an angle of 180º.
From the five pins only two are used so far to convey information.
One is reserved for the shield and the other two for a future expansion.
Every MIDI instrument will have at least two connectors:
- MIDI In: where MIDI information is received by the device
- MIDI Out: where performance data generated in the device is sent out
In case MIDI information needs to be passed from the first receiving module to the third another type of connector is needed:
MIDI Thru: retransmits the information received at the input, making it available to the next device in the chain.
MIDI devices are connected in a daisy chain fashion, where the output of one device is connected to the input of the next.
In such a configuration, there can be two types of devices:
master: sends controlling messages
slave: receives those messages and executes them
Note that the information isn't passed along the chain via the MIDI Out socket which only transmits information that is originated by the instrument to which it belongs. This method of connecting MIDI devices is called Daisy Chaining.
3 - MIDI Messages
Globally, messages sent by MIDI devices can be divided into two types:
Channel Messages: are addressed to a specific MIDI channel, so only devices set to react to that channel will respond to it. The others will ignore it completely.
System Messages: are addressed to all channels and contain general commands such as reset, MIDI tempo, etc. All device in the chain prepared to recognise them will respond.
4 - MIDI Quantisation
Refers to the act of forcing events played to fall on the nearest beat specified. It shifts events (like note-on) to an exact rhythmic position, correcting inaccuracies during the performance. Examples of MIDI quantisation are 4th note, 8th note, triplet, etc. Care should be taken though, since over-quantisation will make a performance sound “robotic”. To reduce the mechanical feel of quantisation, some devices provide a “progressive” quantisation (i.e. 40%, 50%, etc.)
5 - MIDI Implementation Chart
It is a chart that describes all MIDI commands recognised and transmitted by a given MIDI Device.
It is useful if you want to program a MIDI controller to manage certain parameters of your synth, like the cutoff or the LFO rate for example.
Normally you can find it at the end of the manual of your synth.
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