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Computer Editing: Multi-Camera Editing

Here are some helpful hints for editing multi-camera footage into a finished production.Imagine for a moment that you plan to tape an event with three camcorders and edit the three shots together into a single seamless production. With the help of some friends, you position three cameras in the auditorium and roll tape as the curtain rises.

Combining those three tapes into one may be more challenging than you had anticipated. This article will teach you how it's done so you can make magnificent multi-camera edits.

A successful multi-camera edit starts at the shoot. Before your camera operators start recording, make sure each tape is clearly labeled with the production, camera and reel number. For clean audio, it's a good idea to take a feed from the auditorium mixer. Feed it into Camera 1 as your primary sound recorder. You should also make sure the on-camera mikes are active on Camera 2 and 3 so all your tapes have soundtracks. This will help later when it's time to sync the reels.

As the director, use a wireless intercom system (available at Radio Shack) to make sure your camera ops keep the shots varied and as a result don't have any stretches where you have three closeups of one actor, and no coverage of anyone else on stage. At intermission, stop and re-start your cameras to save tape, but other than that, run your cameras continuously from a few minutes before the opening music until after the audience applause dies out.

Then, take all your great footage to your computer room to edit together a multi-camera masterpiece.

Your first chore is to launch your video editor and commence digitizing your footage. Remember that running three cameras produces three times the footage of a single camera.

Make sure you have plenty of free hard drive space on hand. If you're digitizing at DV resolution, (720x480) each camera will generate roughly 13GB of data per hour. Multiply that by three cameras and it's easy to see why storage is an important issue when you're doing multi-camera editing. Another critical issue is the size of the actual files on your hard disk. The maximum file size your hard disk allows you to capture may be considerably less than 13GB. For example, Windows 95 may be limited to 2GB files and Windows 98 may be limited to 4GB, forcing you to capture footage from each source tape in chucks that you will re-assemble on the timeline. See the Size Matters sidebar for more information.

The key concept in multi-camera editing of real-time events is stacking your clips on successive timeline tracks, then dragging them until each track is in perfect sync with its neighbors (see Figure 1).

A shot-syncing shortcut harkens back to film crews who filmed visuals and recorded audio separately, a process known as "double-system" recording.

Filmmakers realized that a sharp sound combined with a visual marker would make syncing up a soundtrack easier in post-production. Thus, the clapboard was born.

At the beginning of each take, they would film a wooden slate that contained production information. Attached to the top of the slate was a hinged stick. When the camera and sound crews called "speed," indicating that everything was rolling correctly, a production person would jump in front of the camera(s) and bring down the hinged stick with a hearty clap sound.

In the edit bay, they synchronized the sound of the clap and the visual of the stick, and the sound wound up in sync with the picture.

Today's video cameras are so adept at recording sound on a single system, that a clapboard isn't really needed. But some kind of synchronization cue can be a big help if you know you'll be editing multi-camera productions.

One sync trick comes from the wedding industry, where videographers and photographers traditionally work side by side. You can use a still camera flash to synchronize multiple video cameras. At the start of the production, when all cameras are rolling, have someone walk across the stage, point a flash camera in a direction where all the video cameras can see it, and set it off. In the post suite, the flash will typically occupy a single frame, and if you line up the flash points of all the camera tapes - you're in sync. Of course, you can get the same results with many quick-action events. In a pinch, having a production assistant walk in front of the stage and flap their arms up and down can be just as effective as a flash or clap. The point isn't the synchronizing action; it's being able to locate the same moment in time on all three cameras.

Sound can also effectively synchronize the footage, a task accomplished easily with a handclap or a clapboard clap. Since most editing applications display the waveform of the audio on the timeline, visually lining up the distinctive peak from a sharp sound, such as a clap, is easy.

Modern camcorders, provided they are powered correctly, run at rock-solid speeds, so once you establish a sync point, it should hold until somebody turns off, stops or pauses any of the cameras. DV footage is striped with time code, guaranteeing dependable synchronization.