If you have a video of a concert — say, for example, your daughter’s orchestra performances — there are ways to extract just the audio so you can produce a CD of the event or rip the music to your iPod.
The easiest way to do this in iMovie ’08 and ’09 is to select the portion of the movie from which you want the sound track and drag it into the Project pane. Now choose Share -> Export Using QuickTime. In the Save Exported File As window that appears, choose Sound to AIFF from the Export pop-up menu and click the Save button. iMovie will export a file that contains just the sound track. You can then drag that audio file into iTunes and have your way with it. Repeat for other clips.
GarageBand is another option. If you’re using GarageBand ’08, create a new music project and choose Track -> Show Movie Track. In GarageBand ’09 you can simply create a movie project and a Movie track will automatically be created. From here on out, the two versions work the same way.
Drag your movie into the Movie track. A new audio track called Movie Sound will be created below the movie track. Select the Movie Sound track and click in the sound wave where you’d like to create an edit point—at the end of a song, for example. Click out of the Movie Sound track and then click just the portion of the audio you want to select. Press Command-C to copy the selected clip.
Create a new Real Instrument track. Click the Rewind button so that the playhead is at the very beginning of the track. Select that track and press Command-V to paste the audio you copied into this track. Choose Track -> Hide Movie Track to do exactly that. (You do this because when you do, your export options change so that you can easily export just the audio.) Mute the Movie Sound track by clicking the small speaker icon next to the track’s red Record Enable button. (Muting this track tells GarageBand to not export this audio.) Choose Share -> Send Song to iTunes. Your active audio track will be sent to iTunes.
To pull additional bits of audio from the movie, unmute the Movie Sound track and repeat this procedure, making sure to always put the playhead at the beginning of a new track and muting the Movie Sound track so it isn’t exported.