Understanding audio tracks

A movie program can play several sources of audio at once. For example, while you hear the audio that was recorded with a video clip, you may also hear a musical soundtrack and some narration that was recorded later. When you’re working on a movie project in your editing software, each of these unique bits of audio would go on its own separate audio track in the timeline. Most editing programs provide audio tracks for main audio (the audio that was recorded with a video clip), music, and narration. More advanced editing programs offer you many more audio tracks that you can use any way you see fit. Adobe Premiere, for example, can provide up to 99 separate audio tracks in the timeline. Although it’s difficult to imagine anyone actually needing that many audio tracks, having too many is better than not having enough. Pinnacle Studio provides three separate audio tracks. To lock a track in Studio, click the track header on the left side of the timeline.
Apple iMovie handles audio tracks a little differently, but you still have essentially three audio tracks to work with. The main audio track is actually hidden inside the video track. Two other audio tracks handle sound effects and background music. You can extract audio from video clips if you want (simply select the clip in the timeline and choose Advanced>Extract Audio), but doing so causes the main audio to take up one of the other two audio tracks. You can enable or disable audio tracks by using the check boxes on the right side of the timeline. This is helpful during editing when you want to hear just one or two audio tracks at a time.