If you're working on a multimedia piece, you're probably focusing your concentration on the visuals. If the sound environment that will surround your presentation seems hard to put together, relax. Multimedia presentations have some ready-to-use, standardized music and sound resources, and MIDI should be your first choice for the music.
What is MIDI, anyway? Think of it as an agreement among different music manufacturers on how to play musical notes on synthesizers. The MIDI specification covers everything from the content of programming code that triggers and orders notes, to control of musical effects these synthesizers can sound.
Originally used for expensive professional music synthesizers for TV/film scoring and recording studios, the popularity of the PC has spawned several generations of tiny but powerful MIDI synthesizer chips fitted onto multi- function sound cards. You know, the ones you scrunch into your PC and plug those (ever-more-expensive) powered speakers into.
The modern soundcard is really multi-functional. Typically it has the MIDI synthesizer chip, a pair of analog/digital (A/D) and digital/analog (D/A) conversion chips, and a small 4 watt amplifier. The A/D D/A chips synthesize actual sound, and save it to your hard drive in giant chunks of bytes--usually in Microsoft's standard .WAV format. You might at first think this is the best way to go for the sound environment for your presentation. But if in fact you mold your sound track using only digitized sound files, it will take much longer to create, edit, and process. It'll hog your system's resources, too.
MIDI music makes a much more efficient and controllable music soundtrack. Since a MIDI file is all data, it's pretty small--typically 15 to 150KB. In comparison, a concert quality, stereo digitized sound file can demand up to 10 MB/minute in size.
But will MIDI synthesis sound as good as the real thing? You bet--if you choose your MIDI files with care, or start sculpting your own. You can purchase arrangements of well- known public domain and original music in MIDI file format (on floppy and CD-ROM). The breadth of styles is terrific. They include famous classical themes and pieces, traditional, ethnic, and familiar favorites--from melodies where Muzak was born to faithful note-for-note transcriptions of Beethoven piano sonatas. There is also a variety of original contemporary pop and "production" MIDI files appropriate for corporate topics.
In order to tailor the length and arrangements of these pieces to your presentation, you'll need to use a musician's word processor for music--a software sequencer. Using a sequencer, you can also write your own MIDI files. There's a wide choice of quality Windows sequencers currently offered, from the budget programs such as Winjammer and Powertracks to feature-laden high end packages such as Master Tracks Pro and Cakewalk Professional.
An excellent program on the low end is Voyetra's MIDI Orchestrator Plus. Stable and easy to learn, it has the advantage of being inexpensively upgraded to from the software many soundcards already include with their install packages. It's tailored to the soundcard environment, and offers the piano roll display for writing and editing music Voyetra pioneered in the '80s. This display is easy for non-musicians (and others who don't read music) to work with. It's a grid where the vertical axis equals pitch, and the horizontal axis equals time.
Most other sequencer companies offer a piano roll window, but MIDI Orchestrator Plus couples it with excellent context-sensitive help--just mouse-point to one of those on- screen buttons. There are other windows as well for handling measures and tracks, mixing the output to the soundcard's synthesizer, and limited but elegant music notation.
If you can pick out notes on a piano keyboard, you can record your own melodies or chords into any of the current sequencers. You'll need a keyboard with a MIDI-Out plug (check that old Casio or Miracle you or a neighbor may have in the upstairs closet). Don't worry what sounds this keyboard makes (probably cheesy)--you won't be using them. You're just using the MIDI keyboard to play "note data" into the software sequencer. The sequencer will trigger the synthesizer chip on the soundcard. To send the data from the MIDI keyboard into the computer, connect its MIDI-Out plug to the soundcard via a MIDI connector that will typically fit into the joystick port of your soundcard. You can find such a connector from many music stores (under $30), or from your soundcard's manufacturer.
If you're reading this and saying "I have no idea how to write my own melody!"--or if you're just under a deadline-- it's easier to create the sound track using existing MIDI files, and adapting them to your presentation. You'll use the same windowed tools of the sequencer for adapting the musical files, in order to time them to begin and end at the right time, and change the music according to the changes in your slide show or animation.
An overall "bar view" window will allow you to cut and paste groups of measures, and shift one instrument's part to another "track". The note edit and/or piano roll windows will allow you to edit or enter new notes and chords. Another window will allow you to send a track's music to one or several simulated instruments in the soundcard's synthesizer. There may be a special window or other tool to help you write a drum part, where the different percussive pieces of the drum kit are mapped onto special pitches in the piano roll window. They won't sound those pitches, but this drum map will allow you to edit and write drum parts.
The controlling virtual data path that the General MIDI standard provides for all of this is the MIDI channel. For example, channel 16 is the agreed-on basic channel for MIDI drum music. Your windows sequencer will know that all notes on a track defined as channel 16 will sound as the drum map. It's suggested (but not mandatory) to use channel 13 for melody, channel 14 for accompaniment such as the piano part, and channel 15 for the bass part. This are the four basic, or base tracks of a typical General MIDI file, the current Windows standard. Your soundcard's synthesizer chip may play more instruments on extended channels (channels 1-12), as well. But the base channels are an excellent starting point, and composers like myself are able to do quite a lot with them.
Very often a MIDI file you purchase will have two arrangements side-by-side: one on channels 13-16, and another on 1-12. For an example of this, check out the file CANYON.MID that Microsoft provides with every copy of Windows, in your Windows directory. Your Windows "MIDI Map" controls what channels will play. You can find your MIDI Map in the Main Program Group (go into CONTROL PANEL\MIDI MAPPER). You can also audition CANYON.MID by going into the Accessories Program Group and clicking on that `filmcan icon' labeled the Media Player. In the Media Player, click on Devices\MIDI Sequencer, and load and play C:\WINDOWS\CANYON.MID.
Load CANYON.MID into the sequencer you've chosen, and experiment with editing notes and measures, rearranging tracks and parts of tracks, and changing the program numbers (really instrument numbers) of channels to hear different instruments play the same section of music. Try altering the length of the file, as if you're matching it to a presentation.
There are many sources for MIDI files that you can use royalty-free as the background of your presentation, with some restrictions. Typically, as long as you don't re-sell them (or distribute them en masse) you can use as many as you like. Make sure they're mapped to General MIDI. If they're older MIDI files, make sure they're in Standard MIDI File Format.
Your authoring program can be used to cue your music files-- and trigger any voice-overs or sound effects as well. These will probably be .WAV files, and your multi-function soundcard can play them at the same time as the MIDI music. So roll up your sleeves and get your hands on that software sequencing program. You'll probably really enjoy making music!