Almost every recording studio has some instruments. And almost every modern electronic instrument has MIDI interface. This is the interface you will use to connect your instruments with computer. You will also need some MIDI software to record, edit and play back your music. Most people recognize the MIDI interface by the three 5-pin ports labeled IN, OUT, and THRU, found on the back of every MIDI device. But what exactly is MIDI? What can MIDI software do?
What Is MIDI?
MIDI (musical instrument digital interface) is a protocol – a standard of communication between devices - musical instruments (and computers). MIDI is useful for recording instruments and then edit your recording: changing tempos, keys, time signatures, and instrument sounds. With MIDI you can also write music that no human could ever perform - you don't have to record anything. The standard is flexible and allows you to manipulate musical notes in any way you see fit.
How MIDI Works
In general, MIDI-enabled device communicates with other MIDI-enabled devices. One device can be a synthesizer, external sequencer or MIDI controller keyboard, the other device can be a computer with some MIDI software. MIDI messages tell an instrument, a computer software, or other MIDI device when to start and stop playing musical notes. MIDI also handles other important musical elements, such as pitch, pan, volume and modulation, when to change instrument sounds, the start and stop points of a song, and tempo. MIDI devices communicate with each other by exchanging data. For example, to play a note, to change pitch, or to change volume.
MIDI is not audio
You should understand that MIDI is not audio. It is only data to control the sound produced by the MIDI device. MIDI does not work the same way as digital audio hard disk recorder. You cannot record live music or singing using MIDI.
MIDI is a protocol – a communication between MIDI devices. On of the important protocol phases is to agree to use the same MIDI channel. MIDI can operate on 16 channels numbered from 0 through 15. MIDI channel is one of the information that is part of messages exchanged.
The MIDI Interface
The MIDI interface has three ports In, Out and Thru. The In port receives messages from other MIDI device and plays the device according to the incoming data. The Out port sends data to other MIDI device. The Thru port outputs the same data as it is received on the In port. It is used to connect multiple MIDI devices.
MIDI devices can be either slave or master. A master is any MIDI device that sends data through an Out port, while a slave is any MIDI device that will generate sound from the data being passed from, or through, the master. Notes played on the master keyboard are sent to all slave keyboards, which will sound when the master is played. You only need to make sure that the channel you set on the slaves is the same as the master channel.
Hooking It All Up
To hook up two MIDI devices, you connect the Out port of the first device to the In port of the second device. When you press a key on the first device, both devices will play. But when you press a key on the second device only the second device will play. This is because the first device is only sending MIDI data, it is not receiving anything from the second device.
MIDI communication contains MIDI messages, which instruct a synthesizer to play sounds by telling it which sounds to use, which notes to play, how loud to play each note, and so on. A synthesizer in this context is any electronic device that contains a set of predetermined sounds that have already been sampled and hard coded into hardware or into software on a computer. The two widely used technologies to generate sound are FM (frequency modulation) synthesis and wave table synthesis. FM synthesis means modulating (controlling the frequency of) a carrier signal with another signal. Wave table synthesis stores sound samples in digital format, allowing you to play those sounds on demand or via MIDI. This is currently the most popular way of generating sound in professional synthesizers and computer sound cards.
Recording in MIDI is generally referred to as sequencing. It is more or less the process of recording all of the note events corresponding to what you play on your instrument. Using an external sequencing device, an onboard sequencer, or, more commonly, sequencing software with your computer, you can record, store, play back, and edit note events.
A computer is an ideal tool for using MIDI, it only needs a MIDI interface and MIDI software. There are many different interfaces available for almost all types of computer systems. For a PC, most standard sound cards have a MIDI interface built into the joystick port, while Apple supports MIDI in most of its current models through a USB port. A computer functions in much the same way as any MIDI device, but it is used a bit differently. A computer works best as the main MIDI data driver, meaning it supplies MIDI data to the rest of your MIDI-enabled instruments. In addition to driving the MIDI data that “plays” your MIDI devices, your computer with appropriate MIDI software can function beautifully as the recording device that will capture your MIDI performances, too. Using MIDI software, you can receive incoming MIDI data, record it, play it back while recording new tracks, save it to your hard drive as a file, re-open it later, or share it with anyone who has the ability to play MIDI files on a computer.
Connecting Your Computer
The easiest setup for connecting your computer to some MIDI device is a simple matter of connecting the In port to the Out port and vice versa. With both the In and Out ports in use, you can use a MIDI-enabled instrument, for example, to input MIDI data into the computer as well as play MIDI data using the computer to control playback.
The MIDI File Format
To store MIDI data MIDI software uses a binary file format with the .mid file extension. The format is not a simple text file, so you cannot open it up and view it directly. You need a MIDI software for viewing, editing or playback. The MIDI file format specification actually sets up three types of MIDI files: MIDI Format 0 (stores all MIDI sequence data in a single track), MIDI Format 1 (stores MIDI data as a collection of tracks), and MIDI Format 2 (generally not used or supported by most MIDI software). For MIDI studio recording, Format 1 is the most useful because you can edit and view individual tracks.
There are many software programs that support virtually anything that can be done with MIDI. In the last several years MIDI software has expanded to include also digital audio recording capabilities. MIDI software price range starts from zero for freeware programs to professional packages that run into thousands of dollars. Some of the most popular MIDI software packages are Cakewalk Sonar
(Windows and Mac sequencer now with integrated MIDI and audio), Logic Audio (Apple's MIDI & audio solution for the Mac), Digital Performer (a complete digital audio and MIDI production environment), Studio Vision Pro (a Mac-only MIDI and digital audio recording and sequencing application), and Cubase VST (a professional-level application that combines MIDI with digital audio recording available for both Windows and Mac).