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How to Sync Dual System Sound

Capturing flawless video and awesome audio is certainly a crucial part of the process, but if the two aren't properly synchronized in post then the results will surely be disastrous. We show you how to bring it all together using timecodes, slates and waveforms, and synching software, to keep your project's timing on track and looking and sounding it's absolute best.

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Video Transcript

Capturing flawless video and awesome audio is certainly a crucial part of the process but if the two aren't properly synchronized in post then the results will surely be disastrous.
Next, we show you how to bring it all together using Timecodes, Slates and Waveforms, and Synching Software,
to keep your project's timing on track, looking and sounding it's absolute best.

Working with dual system sound involves recording audio simultaneously to two different devices, such as a camcorder and a separate audio recorder. Wouldn't it be great if we could just roll camera and capture excellent audio and video, perfectly synchronized and ready for distribution? The truth is that you can capture both together, but if you're looking for quality, the results will probably be less than you would like.
Even if your camera is capable of producing pristine images, chances are, that the awesome audio you're after, will be recorded on a separate device altogether. Today's DSLR cameras are used to produce high-end television commercials, and even feature length movies, but their audio capabilities are notoriously awful.
You may even find yourself on a multi-camera shoot where video and audio from several different sources will eventually find their way into post. Poorly synched audio is painfully obvious.
If the audio and video are out of synch by even a frame or two you can rest assured that that will be the only thing your audience remembers. Thankfully, there are a number of methods for achieving perfect synchronization both on set and in the edit bay.
If your budget is burgeoning with beaucoup bucks then you might try the Hollywood solution by using synchronized timecodes. A master device, or timecode generator, is used to send continuous matching timecode to several slave devices. These might be a single camera and an external audio recording device or on a large set may include multiple cameras, multiple audio devices and a digital slate. The idea is that every device will display precisely the same timecode at exactly the same moment in the production.
Once in the editing software in this example we're using Adobe Premiere Pro place each clip on a different track, select all the clips and right click. Click Synchronize in the menu that appears, then in the Synchronize Clips dialogue, click the radio button next to Timecode and click OK. The software locates the first place where all the timecodes match and lines them up accordingly.
For a lower tech, less costly and only slightly more involved solution, use a slate or clapboard. Slates feature a small dry erase board for displaying important information such as the current scene and take number.
A strip of wood is attached to the board with a hinge so it can be raised and lowered. While rolling, the slate is held in plain view of the camera, or cameras. At the director's cue the scene and take numbers are announced, followed by a loud snap, as the hinged portion is raised and then rapidly snapped shut.
This action provides both an audible and visual cue so the audio and video tracks can be properly synched up later. A similar result can be achieved using a clapboard, which is nothing more than two pieces of wood held together with a hinge, or by simply clapping your hands in front of the camera. This audio portion will act as your guide.
Scrub through the video until you find the place where the slate is snapped. Notice that there is a distinct spike in the attached audio waveform at the exact moment the clap happens. Drag the matching audio clip from the separate recording device onto an empty track below the video. Locate the same spike on the new clip's waveform and line it up with the spike on the original clip. Mute the audio on the first clip, link the new audio to the video and you're ready for the next clip.
Another option is to use one of the synching software solutions that are available such as PluralEyes and Final Cut Pro X's automatic audio synching feature. For Final Cut, simply select both the video clip and the audio clip you want to synch to it. From the Clip menu tab select Synchronize Clips and that's it! A new clip is generated with the synched up audio and you're on to the next clip.
Similarly, PluralEyes, by Singular Software, automatically synchronizes your video and audio clips without linking cameras, generating timecode or slating. In your editor, create a new sequence with your clips you want to sync. Next, export an XML Premiere. Open PluralEyes and import your XML file. Choose replace audio to over-write the original clip's audio with the unsynced file. Click sync. PluralEyes analyzes and synchronizes everything automatically. Simply import the newly synced XML file back into premiere and you're set.
For perfectly matched video and audio every time, use the synching strategies we've outlined here. Whether you synch with Timecodes, Slates and Waveforms, or software, you can be sure your audience will enjoy the high quality audio you've achieved, by working with, and successfully synching, dual system sound.


ajeremiah71's picture

I have a question downloaded dual software in iMac but it appear didn't show the options for synchronizing i contacted the company staff didn't get a help i wanted. So why makes the option don't show in my iMac?