What is MIDI? How do DAWs use MIDI? What are some external devices used with MIDI and how do they work? (Must discuss two of the following options MIDI keyboards, retractable, MIDI guitars, samlple pads utilizing MIDI)
History of Midi
Before Midi there were analogue synths that used Control Voltage (CV) and Gate Triggers to send information. With no universal standard to control these methods analogue synthesizers were very complicated. The first Midi standard was created by Dave Smith in 1983, he convinced the music industry to adopt his new technology saying it would allow synthesizers to be controlled by computers or external keyboards.
How it works
Midi is completely digital so no sound is being sent through it. Instead it sends event messages, these can include note on/off, velocity, aftertouch, pitchbend, volume etc. Midi can support up to 16 channels meaning that up to 16 different Midi capable devices can be connected and controlled on a single chain. It also supports SysEx meaning that developers can include features that only their equipment will respond to, for example a unique id is sent along the midi chain and only devices set up to recognize it will respond while other devices simply ignore it. Midi is sent using a 5 pin DIN connector. Only 3 of the 5 pins are used in a Midi connection, one is used as a ground or sheild, one is used as a +5v connection or current source while the other is used as a current sink or signal out. As the signal is sent digitally the pins will either carry voltage or not corresponding to 1's and 0's. Midi supports up to 31,250 bits per second. Midi can be connected by usb but at the cost of higher latency and higher jitter.
Midi Application
Midi can be used in many ways, these include Instrument Control, Composition, Midi file sharing, notation and more. Midi was invented so that instruments could communicate and control one another. For example when a note is played on one instrument it can trigger and play the same note on another. It also allows other parameters to be controlled remotely such as on synthesizers. Midi is also designed to be used with DAWs (Digital Audio Workstations) to compose music. These work in mostly the same way as synthesizers except the computer is doing everything. It is possible to save Midi sequences and transport them to another computer, the computer will save the sequence as a SMF file. This file can then be opened on another computer and played provided the 2nd computer has the appropriate samples. It can also be used to transcribe whats being played on an instrument into sheet music using score writing software.
Midi Inside a DAW
A DAW (Digital Audio Workstation) is an application that is used to create, record and edit songs and audio files. Logic Studio is an example of a DAW, it also takes advantage of Midi when producing music. This has lead to new features being included in the software such as Quantisation, Midi Draw and Region Inspector. Quantisation is a feature that corrects rhythmic errors after a recording from a midi device. It moves notes out of time to the nearest grid position, it also has more advanced options like the ability to shift clusters of notes and change the length of notes to better suit the music style. Midi draw is a feature that shows on screen the characteristics of the midi data such as pitch bend, modulation and volume. The Region Inspector allows the user to "clean up" recordings by smoothing out jittery sections in the recording by changing the velocity settings and the dynamic of notes. It allows the user to change the timing of sections using delay.
External Midi Devices
As you can see in the video Reuben connects an external midi keyboard to his Mac via USB. This allows him to play notes on the midi keyboard and have the DAW he has open translate them into sound that are then played through his monitors in real time. Reuben then opens a project he is working on and records a piano riff into his project by playing on the midi keyboard. The DAW takes these notes he is playing and stores them in its own piano roll so that they can be played back later without Reuben having to play along with the track.
