Sync the audio and the video together in your video editing program.
Although most consumer-based video cameras record both the audio and video onto the same tape (or hard drive), you often record the two as separate files when filming a professional video. Although this allows you to easily adjust the two files on its own, it does force the editor (or the assistant editor) to sync the sound and the video together. This is the main purpose for the slate you see marked at the beginning of every shot. Although the information written on the front of the slate explains information regarding the shot, the slate clap is designed to help the editor sync the audio to the video.
1. Open your video editor and import the audio and video files into the program (click “File,” “Import” and select the audio and video files).
2. Double-click the video file and it appears in the display window. Click the “Advance 1 Frame” option to move the video one frame at a time. Stop the video frame exactly when the clapper meets the camera slate. If you did not use a camera slate for your filming (an editor’s wost nightmare), you must find a different instance where sound suddenly occurs (such as a branch breaking or a hand clap). The device that creates the noise must be seen on camera.
3. Press “I” or click the “In Point” option to set this as your first “In” point.
4. Drag the video down to the video portion of the timeline.
5. Double-click the audio file and it loads into the display screen. Although there is nothing to see, you can listen to the audio file. Click the “Advance 1 Frame” option to scrub through the audio file one frame at a time. There is a suddenly high-pitched sound right when the clapper strikes the board. Press the “Input” option to set this as the first audio “In” point.
6. Click-and-drag the audio file down to the audio portion of the timeline. The sound and video are now synced together.