The right way to sync your audio & video

Understanding the importance of audio in video

While you can get by with middling image quality in a movie or TV show, bad audio makes the viewing experience next to unbearable. Whether you’re filming your next viral YouTube video or just recording a webinar for colleagues, it’s worth it to take the time to get clean and clear audio in the process.

You might be able to squeak by relying on your camera’s internal microphone, or even the one on your phone — most phones have great microphones. But relying solely on your camera or your phone to record audio runs the risk of audio disruptions such as scratching, hissing, rustling, and background noise. Plus, the subjects in the video might sound like they’re far away because, well, they are — using your camera’s microphone means recording your subjects’ audio at a distance.

If you want your video to sound the best, you should record the audio separately. This means buying (or renting) things like a boom mic, a directional shotgun mic, or a lavalier you clip to your subject’s clothing. You’ll also need an external recorder and possibly a mixer to capture all the sound (plus, of course, the corresponding cables to hook it all up).

When you’re recording your video, make sure you have your external recorder and camera ready to go, that they’re both rolling, and that you create a ‘sync point’ before every take by clapping your hands or a slate board. (Slate boards, also known as clapperboards or clappers or sticks, are great because you can see as well as hear your sync point.) Once you have a rich audio recording, the next step is lining it up with your video footage.

How to sync audio and video with Descript

There are several programs you can use to combine separate video and audio tracks, but we’re obviously partial to Descript. You can easily sync up your audio with your video using the visual waveforms in Descript's editing tool. Here’s how:

1. Import your audio and video clips

If you haven’t yet, download the Descript desktop app for your computer, and then install and open it.

First, create a new project by clicking the blue “+ New” tab in the upper right-hand corner of the Drive view and choose “Project.” Choose a name for your project and click “Create Project.”

To add your source audio and video files, you can click on “Add new…” in the upper left-hand corner and select the files, or just drag and drop your audio and video clip into Descript.

2. Create a sequence

As soon as your audio and video clips have been imported into your Descript project, create a new sequence by clicking “Add new…” and then “Sequence” from the drop-down options.

Now, highlight whichever audio and video clip you need by checking the boxes next to each file.

From there, click on the ellipsis to the right of one of the clips to access the dropdown options. You want to choose “Create Multitrack Sequence.”

Your Descript editor should show one track with the video clip and the corresponding audio and audio waveform, and one track with the externally recorded audio and the corresponding audio waveform.

3. Syncing audio with video in Descript’s timeline

First, find the mutual sync point in the video and audio clips, which is the moment at the beginning of a take when you clapped either your hands or a clapperboard to create a point of synchronization.

Find the sync points one at a time, which you can do by muting one track (clicking the “M” to the left of the track) and listening to the other track and making note of the sync point when you find it. Then mute your second track and listen to track one to listen for that track’s sync point. A clapperboard sound or any other sudden clap usually has a sharp jump in the waveform.

Once you’ve located and noted both sync points, make sure you’re on “Select” mode by clicking the arrow symbol under the video monitor. With the Select tool, click on the track with the earlier sync point and then drag it over till its sync point lines up with the corresponding clip and track.

Once you have the two tracks lined up, confirm the audio and video are perfectly synchronized by playing the video at a handful of random points along the timeline to see if everything looks and sounds synced.

Once you’re done editing your project, go share your synced video far and wide! You’re a wizard now! Congrats!

3 tips for syncing audio and video

There are a lot of moving parts when recording a video, and even more when you record the audio separately. Here are a few tips to keep in mind that will help you get the best quality recording and make it easier to sync your audio and video.

• Remember to create a sync point. Once your camera and external audio recorder are rolling, have someone stand in front of the camera, call the scene and take, and then clap — with either a clapperboard or their hands — loud enough that it’s caught on both the camera and audio recorder.
• Check your levels. Before you call action, be sure to test your audio levels in your mixing software on every mic, especially the mics used for picking up dialogue (such as a lavalier). In mixing software, you can see the decibel levels on a colored bar that moves between green, yellow, and red. Background noise should be in the green, while a person speaking should stay in the yellow and sometimes touch red so that they can be heard clearly in playback. If a speaker’s mic is frequently hitting red, you can adjust the gain of their mic, either physically or in the mixing software. There’s no way of fixing blown-out audio in post (a.k.a. audio that is too loud/in the red), so make sure the audio you record is clean from the get-go. Remember: when it’s too loud, you’ll never feel proud. That works, right?
• Use multiple mics. Use both your camera’s and external recorder’s audio to help you sync audio to video. Even though you might discard the camera’s audio entirely in the end, it will have the same wavelength pattern, which makes is essential to lining everything up.