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The world of MIDI

Oct 25, 2002 - by Synthetic
    Midi is the ying and the yang of electronic music. Some rejoice in its presence while others loathe its latency-ridden timing and flaky implementation in some devices. So depending on the day and whom you ask, many different opinions on midi can be found among musicians. Many performing musicians will keep their distance from midi, as they don't feel it has the accuracy and reliability to be integrated into their live performances. Studio musicians see that midi has opened up many new creative possibilities for their music, and they can no longer live without it.

    So just what is this midi protocol that is both so hated and also loved and embraced? Midi in a nutshell is simply code that is sent digitally between devices and carries information that it shares with computers, drum machines, keyboards, sound modules, controllers and more. Midi alone cannot produce sound for it has no actual audio data. Midi can however tell a synth module what notes to play to create sound. For instance, if you use a midi controller such as a keyboard, you can send midi messages to another device such as a desktop synth module (???do you mean an expander or a virtual synth on a computer???) telling it what note to play as well as information such as volume, panning, aftertouch (an expressive way of manipulating a sound by holding down the keys and pressing harder), note length and velocity. Basically, you can think of it as remotely controlling the sound module which provides the instrument sounds.

    So, looking back at what midi really represents... coded information and no audio... then how do we convert that midi into an audio file that can be recorded on a CD or used in a mix with other instruments? There are a few different ways to go about this. Which method to use is determined by what software and hardware a person has access to, and how important sound quality is to that person.

    The most general and easiest method for creating audio files (.aiff or .wav files) is to get a hold of a program such as the RolandED VSC-88H3 also know as Virtual Sound Canvas. It is a midi software synth capable of producing .wav files from midi files using its library of sounds. This may be the easiest option for those who have midi files and want to transfer them to a CD for listening on regular CD players. However, the sound quality will neither be up to par with most commercial audio CDs, nor even as good as most indie artists due to its lack of sound appeal and limited audio dynamics. Also, keep in mind a midi file will only sound as good as the person who created it. Some midi files are very crude with little articulation and sometimes even off-key, while others are very detailed and add lots of expression.

    The best method for getting audio from midi files involves a bit more work and more investment in software or hardware, but the results are worth it in the long run especially for anyone creating music and who wants control over the sounds used. Most commonly, midi files are loaded into a software sequencer on a computer and used to send note information to external hardware sound modules such as samplers, synthesisers and expanders.

    Now one must wonder how it is possible to get so many different instrument sounds from one midi file. The solution is to use what is known as channels. In its simplest form, a midi setup with one input and one output will have 16 channels that it uses to send the information. Think of this connection physically as a thick cable housing 16 smaller cables inside.

    Technically this is not how the midi cables are made (MIDI transmission is serial, not parallel). Itís just a way to visualise midi channels. Each channel of this midi cable may carry note information for up to 16 different instruments in a musical score or composition. Here lies the magic of midi... we are now able to use one midi cable to send note messages to one multi-timbral sound generator such as a synth or sampler, and have it create audio playback of up to 16 instruments. This audio is then routed from the sound module back into the sequencing program or to whatever recording medium a person has to create the audio file of that midi file.

    It is also possible to use multiple hardware modules to create the different instruments but then the setup becomes a bit more complex. Most midi devices come with 3 MIDI connections these days. You should find at least an input and output port and maybe even a thru port. The input would be through the midi cable coming from either your midi interface connected to a computer and sequencer software, or from a hardware sequencer. The input may also come from a controller such as a keyboard if you intend to record a performance. The output is needed only if the user desires to record the midi data of a performance for editing purposes and composition in a sequencer (software or hardware). The thru port is the least important port unless you have multiple sound modules to use with midi, and only one midi port coming from the sequencer. Ideally, if you have more than one midi sound module that you wish to use, its best to have a separate port for each module unless you record one module at a time, but then this will require mixing and editing of the files later, after audio has been recorded. The reason to avoid using the thru port is latency for the most part. The thru port will allow you to send midi channels to another midi device creating a chain of sorts but latency might make the devices seem a bit out of time depending on the device and midi sequencer. This has led to the development of new midi interfaces with four and more ports to support multiple midi devices.

    Midi can open a whole new world of options when working with computer and electronic music devices when you consider all the possibilities. Ideally, using midi... a person can create a studio environment that is totally controlled from one central location using a computer, a keyboard, or sequencer or any combination of the three. Example, a recent article from Keyboard magazine describes the home studio of Moby. He has a PowerMac G4 computer running ProTools for recording the audio for all of his tracks, and another computer running Cubase as a sequencer. Midi is routed from the computer running Cubase to several locations. One location is a rack of synths, and fx units connected via Emagic Unitor8 8-port midi interface. That's not all, he also has a nice collection of keyboards that are housed in a cabinet on pull-out shelves that are also connected to another Emagic Unitor8 interface (you can use multiple interfaces). Moby claims that he normally relies on a weighted Kurzweil keyboard to control his other keyboards and synth modules.

    So how does midi communicate with your computer? As mentioned above, first it starts with a midi interface. Some electronic music devices have been developed that allow computer users to bypass the interface by incorporating the technology into the device itself and allowing the user to connect, send and receive midi using serial connection and just recently USB directly from device to computer. This is a nice feature (Yamaha CS6x synth keyboard uses this feature as well as providing regular midi ports), because it eliminates the need for the interface. A surge in midi controllers has recently made use of this convenience as well offering small keyboards that will communicate midi to computers via the ever-so-popular USB protocol. However, if you are not lucky enough to use or own a device with this new trend, then you will need to obtain an actual midi interface that will connect using your computer's USB, modem, or printer port. Many of these are available at most online retailers and maybe at your local retailer.

    Once you have got your midi device connected... it most likely will need to have drivers for either your device (if connecting directly) or for your midi interface (if connecting using actual midi cables). Most likely you will also need to install an app such as OMS by Opcode or Freemidi to allow your midi interface to communicate with your computer software. There are two exceptions to this however. If you are planning to use Logic Audio from Emagic... Logic has its own protocol for handling midi so you donít have to use OMS or Freemidi. However, if you are planning on running other apps that will make use of midi other than Logic, you will almost definitely need the OMS or Freemidi (Logic will use OMS if you tell it to in your setup preferences). The second exception to the rule is if you are running OSX for the mac and plan on using midi. OS 10.2 has midi incorporated into the system for the best possible timing accuracy and OSX apps will recognise this automatically. OMS and Freemidi will therefore not be available on OSX.

About the author: Synthetic
Professional graphic artist by day and aspiring musician by night. I play keyboard and bass as well as write and compose music.
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