Build to Order
Even if you've never picked up an instrument or don't know middle C from a hole in the ground, GarageBand's built-in loops make the application both fun and useful for making music. For example, GarageBand is a fine tool for creating iMovie soundtracks. One problem you're sure to run into, though, is that the app doesn't include a way to cut your piece to the exact length of your video. Sure, you could fade out the soundtrack, but wouldn't you prefer to have it stop at exactly the moment your clip fades to black? With the help of Apple's $30 QuickTime Pro (included with many of Apple's pro apps), you can make your soundtrack do just that.
1. Create Your Movie Once you've edited your movie, note its length, which appears in iMovie's title bar.
2. Export Your Movie Save your work as a QuickTime movie, using iMovie 4's Share command.
3. Run the Numbers To make your music fit, you need to know how many measures it takes to fill the time of your movie. By default, GarageBand creates files with a time signature of 4/4 (meaning that each measure of music contains four beats) and 120 beats per minute (bpm). To determine the number of measures per minute in a 4/4 piece, simply divide the bpm by four -- 120 divided by 4 equals 30 measures per minute, or 2 beats per second.
To give your soundtrack a natural feel, you shouldn't cut off the soundtrack in the middle of a musical phrase -- which in GarageBand is usually four measures long. Therefore, your soundtrack should finish at a measure that is a multiple of four -- at the end of measure 28, 32, or 36, for example.
If you want to be terribly exacting about this, you could alter the bpm setting so that GarageBand generates measures that are a multiple of four every minute. To do so, take the number of measures you want and multiply it by four to determine the bpm. For example, 24 measures multiplied by 4 beats per measure equals a bpm setting of 96. For our purposes, however, simply create a piece that ends within a few seconds of the length of the movie.
4. Create and Export Your Soundtrack Assemble your musical masterpiece and select Export To iTunes from GarageBand's File menu.
5. Launch iTunes and Locate the Soundtrack Select your exported GarageBand soundtrack in the iTunes Library and choose Show Song File from the File menu (or control-click on the file name to bring up a contextual menu with the same option). In the resulting window, drag the file to the Desktop.
6. Put It All Together Piece the movie and sound files together in QuickTime Player Pro. Launch QuickTime Pro and open both your movie and your soundtrack files. Select the soundtrack and press Command-A to select its contents. Now press Command-C to copy it.
Click on the movie you made in iMovie and choose Add Scaled from the Edit menu. This pastes the soundtrack into the movie and stretches or shrinks it to fit the video's length. This will change the soundtrack's pitch, but if the video and soundtrack are close in length, you shouldn't hear a noticeable difference.
7. Mix the Volume If the soundtrack's audio is too loud, you can adjust its volume. Select the movie, press Command-J to bring up the movie's Properties window, and choose Sound Track 2 from the window's first pop-up menu and Volume from the second one. Move the Volume slider up or down.
8. Save Your Movie Choose Save As from QuickTime's File menu. In the resulting Save dialog box, enable the Make Movie Self-Contained option and click on Save. -- cbSound Advice Mix your movie's audio tracks within QuickTime Player Pro.