The issue is that synchronizing high-quality audio against the scratch track from the primary or secondary camera takes time. Lots of time, especially if there are a number of short video or audio clips—again, in the case of DSLR production, with the 12-minute continuous recording limit on Canon DSLR models, all but inevitable.
For live productions, there’s often a single master recording used for archival or post-event editing, which has both the video mix from multiple cameras and the house soundboard audio mix. We may also be working with wireless microphone systems and portable audio recorders. In either case, a standalone multitrack audio recorder’s output can be synchronized using a single sync point at the beginning of the video track, which will stay in sync all the way through to the end of the clip.
What happens, though, if the audio is significantly longer than the video? In the days before digital, a standalone audio recorder was always less expensive to run than a video recorder or film stock, so the audio recorder was started up a few minutes or seconds before the camera. In the editing room, the act of trimming the audio to the length of the shot was standard operating procedure, but was still labor intensive.
Enter Singular Software, makers of the Final Cut Pro and Premiere Pro plug-in called PluralEyes (also available for Premiere Pro, Vegas Pro and, most recently, EDIUS 6.0 on the Windows side). Toss all your video and audio clips on a timeline—it doesn't matter if they're in any particular order—and PluralEyes will attack the task of sorting them out and laying them in the proper location on an existing or new timeline, creating a second timeline for “unknown” audio or video clips.
For those doing production in the field, however, it may not be practical to bring along a full nonlinear editing suite, when all that needs to be done is a basic synchronization of the master video recording, master audio recording, and a series of audio- or video-based B-roll clips. You may also find yourself in situations where your primary editing system is tied up with other tasks and you want to assign syncing chores to another system or application.
For this task, Singular offers a new standalone application called DualEyes, which we put to the test on a jumble of clips, including some DSLR footage and some audio clips recorded on a Zoom H2 audio recorder.
We’d shot the footage a few months ago, but the daunting task of listening through 30 minutes of short audio clips, then manually matching these to a series of short DSLR video clips, was enough to put the task in the to-do list for a time when we’d have 4–6 uninterrupted hours. The primary reason for this length of time was the fact that we didn't know whether any or all of the clips overlapped each other, since we were just randomly grabbing B-roll footage and audio recording during a live event.
What we hoped to be able to do was fairly straightforward: Align the disparate clips, add the combined audio-and-video clips to a timeline that had our master recording from the live event, and then choose whether those clips would be used as cutaway shots from the master recording.
Here's how we did it.
First, we opened DualEyes, and chose the location of a new project. The location is important, because DualEyes will add a temp folder that may run into the 10–15GB range, depending on your source content’s original size and compression; for audio content recorded in AAC or MP3, for example, DualEyes will extract all the audio to the AIFF format (a native Macintosh audio format) for the Mac version of DualEyes.
Second, we then chose which clips we wanted to synchronize, via the program's a very minimal interface of three buttons: add, remove and trim (identified by plus, minus, and scissors icons, respectively).
Third, we waited, while DualEyes cranked through the video clips' audio tracks as well as the standalone audio recorder's tracks. When finished, the program presents the video clip’s name in a left-hand column and presents the new audio clip’s name in a right-hand column. The audio clip’s name will correspond to the name of the video clip, so that it's easy to go to your project folder and find which audio and video clips belong together.
Note that DualEyes doesn't combine the audio and video clips into a single new file, meaning that the original video clip remains intact, complete with its scratch-track audio. Dragging both the audio and video clips into an NLE's timeline or bin, however, will often sync the two clips together.
We’d suggest listening to the audio from both the video clip and the new audio clip before dragging them both into your NLE of choice, as we were surprised that our on-board audio was almost as good as our standalone audio recorder, depending on placement and a few other factors. This kind of value-added decision-making is often jettisoned once an editor is underway with the synchronization task, so we think DualEyes does a good job of saving us from “synchronization fatigue” that often plagues a multi-hour matching session.
Finally, to work our way through the process of choosing which B-roll would work well against the master video recording, we chose to individually import the video clips into our NLE, place them on the timeline and then add the additional audio only if it added to the overall ambience of the scene. This is quite easy to do, since the audio clips are the same length and a corresponding name to the B-roll video clips.
An Issue and an Update
The only area we ran into trouble with DualEyes was when we tossed two audio recordings, from two separate surround-sound recorders, into the project window. In this scenario, DualEyes would trim one but not the other, designating the second recording as “unknown” after it had completed synchronization of the first audio recording.
When we took the first audio clip out of the project window, DualEyes successfully synchronized the second clip to the video B-roll clips. We’re uncertain whether this is an issue with the fact that we’d done these recordings in a surround-sound stereo mode on the Zoom H2, or whether DualEyes would have a similar problem with multiple mono- or stereo-based clips from multiple recordings that simultaneously occur.
So we contacted the company to ask about the issue. Singular CEO Bruce Sharpe immediately set the team to looking at our log files (two files that DualEyes places in a temp folder) and found they could replicate the issue, so an updated version was released (1.0.3) to address the issue. When we ran the tests again, with all the files in the same project, DualEyes successfully synchronized each video clip to not one but two stereo recordings from our separate Zoom H2 units.
School Play Tests
Looking for something even harder, we then tried a set of recordings from a school play that had been shot in 2009. Given the length of the play, and the fact that the audio was in three long segments from each two Zoom H2 recorders, we’d despaired over ever being able to sync this content.
Because the lengths of the audio segments varied for each recorder, and one recorder had only captured half of the play, we figured DualEyes would choke on the ten video clips that partially overlapped some of the audio segments. So we turned on the "Try Really Hard" setting—an option that takes a bit more time to synchronize content.
DualEyes was able to accomplish this complex task as well, turning hours of frustration into just a few minutes of setup and about 30 minutes of quality control (in other words, 30 minutes of me checking various parts of the newly synchronized video and audio segments to confirm for myself that DualEyes had done its job). The company has also released another update, with the current DualEyes version for Macintosh at v1.0.4.
The Eyes Have It
So what's our take on DualEyes? It’s a great program that expands on Singular’s previous award-winning PluralEyes plug-ins for Adobe Premiere Pro and Apple's Final Cut Pro.
Unlike PluralEyes, though, DualEyes is a standalone program ideal for field synchronization of two-system audio- and video-recording sessions before content is even loaded into an NLE. DualEyes provides a way to sync content on a non-NLE machine, leaving the NLE to do what it does best: edit.
DualEyes does its work with an ease that makes synchronization almost seem like magic, requiring very limited knowledge from the user.
Tim Siglin (writer at braintrustdigital.com) is a contributing editor to EventDV, EventDVLive, and Streaming Media.