9.3. Importing MIDI Files

Graphics programs can exchange documents in the form of JPEG files. Word processors can exchange text files. Web-design programs can swap HTML documents.

And in the musical world, the common exchange format for finished musical masterpieces is the MIDI file. As noted earlier in this book, it's pronounced "middy," it stands for Musical Instrument Digital Interface, and it's a compact little file that contains no sound data ”just note-trigger data that relies on a computer or synthesizer to give it a voice.

Hundreds of thousands of MIDI files are all over the Internet, just waiting for you to download. Just go to Google.com, type in MIDI files "76 Trombones " or whatever, and in a matter of seconds you've got a list of instrumental versions of that song, arranged and prepared by amateur or professional musicians , ready to download.

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Tip: When you click a link to a MIDI file on a Web page, it generally begins to play. Your screen goes blank except for a stray QuickTime scroll bar. That's not really the same as downloading the file.In that situation, hit your browser's Back button. This time, Option-click the original link. (Alternatively, Control-click the link and choose from the shortcut menu, "Download Link As" or "Save Link to Disk.") This time, instead of playing the MIDI file, your browser downloads it to your desktop.

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The beauty of downloading MIDI files (apart from their being free) is that you can work with them in your music software. You can import a favorite song into GarageBand, substitute high-quality GarageBand Software Instrument sounds for the cheesy QuickTime sounds that you hear when you play them online, redo the orchestration by assigning different instrument sounds altogether to each line, add some live recordings to boost the realism , and so on.

This vast Web library of ready-to-play music is ideal for exploits like these:

• Practicing . A lot of these MIDI files are amateur recreations of copyrighted pop tunes. But they make perfect "practice tapes" as you work ”in private or in noncommercial gatherings ”on your voice, violin, or viola.

• Karaoke . So you're having a karaoke party, wedding reception , corporate executive roast, or law-school musical revue, and you need backup tracks for singing funny lyrics. Thanks to the Web, MIDI files, and GarageBand, you can call up almost any song in existence and make it sound great ”not to mention adjust it to precisely the length you need ”in a matter of minutes.

• Background tracks . GarageBand tunes make terrific soundtracks for iMovie movies, iPhoto slideshows, iDVD menu screens, and so on. Building music out of GarageBand loops is easy enough, but now and then you really need a specific song in the background. And chances are, you can find it in a MIDI file.

• Interpretive composition . You could rework a familiar tune, giving it your own musical spin, as pop artists for generations have done.

For the first time, GarageBand 2 can directly import MIDI files, so that you can dress them up with effects, add GarageBand's great-sounding drum loops, record some live tracks like vocals, and so on. Figure 9-4 shows the details.

Figure 9-4. Top: Import a MIDI file by dragging it into an empty spot in the timeline (or into a green Software Instrument track).
Bottom: After a moment, GarageBand displays the component tracks of the MIDI file. It should sound pretty OK right away, but most MIDI files become dramatically better once you've spent some time reassigning them to GarageBand's more realistic-sounding instruments.

Once GarageBand is showing the imported musical material, you can play it back, change the tracks' instrument assignments, or adjust the tempo or key. (Most MIDI files "know" where their own beats and measures are, so that adjusting GarageBand's tempo correctly speeds up or slows down the MIDI data.)