|
 |
| Over 1,000,000 Visitors Every Month |
|
|
|
|
| Over 1,000,000 Visitors Every Month |
|
By Mark Johnson Here's a great article introducing you to MIDI without overwelming you with acronyms and techno babble. ...Continued An overview of MIDI Article re-produced with permission of Mark Johnson of the MIDISite.com MIDI started out a decade or more after the introduction of the popular synthesizer module of the late '60s - namely, Dr. Moog's -- MiniMoog. And then once such synths became part of performance and composition, the idea hit to hook up two such synths, even from different manufacturers. And there wasn't any standard, which is still (a bit) the case, today. So, they came up with something called the General MIDI standard. What MIDI does is use a set of codes that hardware devices (even software now) can use to trigger built in sound patches - that is, instruments; but even all sorts of echo, reverb effects, and the like. MIDI data, therefore, is light - very small (and they can be further .zip compressed by 3,4,7 to 1 or better on top of that). MIDI files are miniscule, and easy to send, these days, over 'the net' (which until something like cable modems take off, if they ever do, it's one heck of an advantage over any other kind of file used to produce sound or music). In short, MIDI is particularly the sequence (the codes, the MIDI file itself), but requires broadly the software/hardware to make, to record and manipulate these codes or instructions (the sequencer used to make or change a MIDI file), and also the software/hardware to actually play the instructions/codes the comprise a MIDI in order to make music (the synthesizer used to play the song itself; and "software", because software-only 'virtual' synths are now on the market); and of course whatever software drivers used by the computer. There are other apps that might be used, as well, if a particular sequencer doesn't otherwise include them. MIDI, GM, is really more for backing instrumentals! and instrumentals, generally. A choir-type of sound is possible (cause there are various choir 'patches', choir voices, built-in). So are backing voices, of a sort, possible. But a lead voice - other than a musical instrument that suggests some aspect of the voice (and all do, basically) - generally just isn't there (though my effort at Silent Night comes close, perhaps). It would be just too complicated to get pre-record samples to speak English, or Italian, or whatever, short of a synthesized voice add-on. And it's a drawback where the final song is to be played only on the synth, and not used as merely part of a final studio production. The other thing is that while MIDI includes stuff that can play out on the synthesizer to help with performance styling, expressiveness, the real instruments will necessarily possess more shades and variety than even a 'wavetable' synth sound sample and a good live performer may do things that would be difficult to duplicate, even carefully, with just a MIDI file. But the 'power' of a small MIDI file, within limits, is that it can render even better than CD quality sound, depending on the synth and depending on the MIDI. The sound depends on the synth, whether hardware, software, or some combination, that runs that sequence of MIDI codes. Yamaha got in early, in the 70s, with FM synthesis; which is still the little synthesizer chip on the bare bones sound cards that come with most computers. Recently Roland, Ensoniq, and others, and more recently Yamaha, have placed a far superior synthesizer on PC cards, formerly available only in expensive modules. This uses some sort of sampled, 'wavetable' synthesis, using actual sound profiles from actual instruments, giving potentially a better than CD quality sound (again, of instrumentals). It can sound quite real. It can sound quite 'live'. But it depends on the performance. And the performance IS the MIDI - or perhaps more accurately, the MIDI is a particular performance, on a particular synthesizer. As noted, there's not entire agreement on standards. The synth, itself, may differ quite a bit from one by another manufacturer, using more or fewer 'patches', different effects, and so on. But in order to support these different synths, even if just chips on PC cards, the manufacters have taken to augmenting the GM standard. Roland had vied for setting this standard, originally. It wasn't taken up by the standard's committee. But Roland went with this GM+, they call GS, anyway. And Yamaha went with something called, XG, which is sort of super-GM version, with many more built-in instruments and more and more specific effects. So, unfortunately, for a GM standard, one MIDI file may sound great on one synth, or sound card, lousy on another (and I do mean, lousy). To some degree, at any rate, that's the great 'problem' of MIDI, today; where the MIDI is sent out, but not the rest of the production, as it were. Okay, so that's MIDI [i.e. so how do you mess with it?] But some MIDI sequences include a bit extra. There's a way to set up all the echo and sound effects on a particular manufacturer's synth (even if just the synth on a PC card). And these codes can also be included in the MIDI file/sequence; typically once for the whole song, and right up at the beginning. They are called System Exclusive messages - or SysEx (and while they're supposed to be manufacturer specific, i.e. exclusive, some synths may treat the more common messages in the same way, if they are designed for that sort of multiple-synth compatibility). If you have a software sequencer, you may well need a separate program to set up this SysEx - called, generally, a SysEx editor or librarian. I, myself, found SysEx a little confusing, at first. So, here's a look at it for the Roland GS. In brief, this SysEx controls the built-in hardware filters, oscillators, and the like. Now some (a subset) of these can also be set by 'controller' events, which you can do with the sequencer. So there's some overlap, there. In addition, something called 'registered parameters' (RPN) and unregistered (NRPN) can also set a few (very small subset) of these same things - giving the perhaps confusing variety of commands which really all do the same thing (the situation is like that of large programming languages, like C++, where old methods are kept along with the newer for compatibility, giving many ways of basically doing the same thing). As for sequencers, I recommend the Winjammer Pro. There are other sequencers, also - Cubase, Cakewalk, various. [I recommend the Winjammer 'jukebox' player (if you don't want to buy a sequencer program) from the Winjammer shareware version - but not the shareware sequencer, itself, because it's almost too busted to be useful, except as a demo.] As for Roland SysEx, I recommend the Canvasman, also to be used for single MIDI playback. I mention this (and Winjammer's player) for MIDI sequence playback because the Media Player that comes with Windows is notorious for not playing certain files well. Likely any sequencer player, and Canvasman too, gives a cleaner, smoother sound, for one. And the original Media Player (and also the latest Media Player) is only set up to play a few of the instruments allowed, according to something called a Microsoft MIDI 'standard' (you don't want to know). And as for a notation program, I recommend Noteworthy Composer. [See the links page.] Finally, as to what a MIDI 'looks like', what it can do, this GM standard set aside 16 instruments to play at a time, each in its own 'channel'. But you can change the instrument used in one of those 16 channels at any point in the song/sequence; so it's not quite as limiting as it seems. Typically, the 10th channel is reserved for the drums, and the notes are interpreted as different percussion instruments, or different parts of the drum kit (i.e. a drum channel can have multiple percussion instruments playing at once, but the other channels play only one instrument at a time). MIDI notes and events are placed on any number of tracks, which can play out any of the 16 channels/instruments. You might have tracks 5, 6 and 9, we'll say, playing out channel 3. At any time, channel 3 can only use one patch/instrument. But by the next note, whether from track 5, 6 or 9, a command can be sent to change the patch, and then again, a little further on. 16 channels is the max, again, for GM 1, but you can have many more than 16 tracks (say you want to break out the drum parts into separate tracks, or you have two flutes playing counterpoint, each to its own track, but playing out the same flute instrument). The last general thing, here, is that for each channel, of however many tracks, only a certain number of notes will be played if other channels are sounding notes at the same time. The Roland allows roughly 28 notes at once. The GM standard, and other synths, allow for 32. (If you look at the Canvasman, you'll find a menu for setting aside minimum numbers per channel, in case of this sort of 'overload' condition.) I used to say, at this point, that volumes could be written, and would just refer you to the following introductory material, by following the links just below, if you had further questions. But I though it about time I start the first chapter of the encyclopedia, as it were, and so will begin to elaborate on the above - starting right here. Article re-produced with permission of Mark Johnson of the MIDISite.com
Post Your Comments!
|
Windows 3.1 Macintosh BeOS Linux OS/2 DOS Atari
Tutorials & Advice Discussion Forum Reference Books Free Content For Webmasters Free Banners News Archive Search Guitars
Hitsquad Home Page Privacy Policy SMM People Web Cam Contact Info | |||||||||
|
Home | Site Map | News | Search | What's New? | Discussion | Add Listing |Guitarsite | Advertising
The Musicians Web Center for music resource and industry information on the Net Click here to add Shareware Music Machine to your del.icio.us bookmarks |
 |