March 2014

Synchronizing Audio and Video

Learn how to match music to  moving picture in this video lesson.
In the March issue’s Lights Camera Audition article, we talk about getting good sound for video, and how it can be an advantage to record sound separately and sync it to video after the fact.

In order to do this, you can use audio software that supports video—which is a common feature found in programs ranging from GarageBand to Pro Tools, Cubase, Ableton Live, Logic, StudioOne, Cakewalk, and others.

You can also use any video editing program that allows multiple audio channels, such as iMovie or more advanced software like Final Cut and Adobe Premier.

Either way, your goal is to the start time of both recordings so that the sound plays in sync. Here’s an easy way to do it. 1. Save every take as a separate recording

on both the video camera and the audio recorder. Label the takes so that your sure which audio goes with which video. 2. Hit record on both devices and create an audio mark by clapping or using another percussive sound. Percussive sounds will show up the audio track display of both the video editor and the audio editor. Do this for every take. 3. Once you choose a take, load the video file and the audio file that goes with it into your editing software. 4. Make sure the software is set to show audio waveforms. If possible, trim the audio waveform so that it starts right on the clap. This can make it easier to match the two audio tacks. 5. Using the clap as a guide, slide the audio waveform over so that the clap in the audio lines up with the video. Start by zooming out to get close, then zoom in to get as precise a match as you can. 6. Play the video and mute the video’s original audio track, and check your work. If the audio sounds a bit out of sync, you can move it back and forth one frame at a time (this command is often called “nudging”) until it lines up. If you feel like it’s still off, turn on the original audio and check it. If it’s off by more than a few milliseconds, you’ll hear an echo. If it’s slightly off, you may hear a sweeping sound. If it’s on, the sound should be similar to what you’d hear from two microphones recorded at the same time. 7. Once you’ve got the video and audio lined up, play with the mix a bit: sometimes, a little ambience from the camera’s mic can sound good mixed with the a close mic from the audio recorder. 9. Use your software to export a new version of the video with the new audio track in place. Then save the original audio and video files in case you need to go back to them later. Check the resulting video. If it matches, you can now use this to do any additional editing (such as trimming excess at the beginning of the video, adding titles, etc.). The following video offers a tutorial.

Learn how to get your picture to match your sound with these video lessons…read more

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