Post Production

Shot Transitions When Editing Dialogue Tracks: Basic Rules of Thumb

Moving smoothly from shot to shot is what makes a scene believable. Managing noise is what makes a scene bearable. Keeping processing to a minimum is what makes a scene natural. Balance these competing interests and a scene will work. There are a few overarching principles that are common to all edits from one shot to another. Work with these basic rules in mind and the rest will largely take care of itself.

Rule One: Whenever Possible, Play Only One Source of Room Tone at a Time

Let each shot speak for itself, overlapping room tones only at transitions. It’s true that there must be constant room tone running the length of a scene. After all, it’s the air that a scene breathes. However, in most circumstances the room tone comes from the regions themselves. Only when there’s a hole in the production track do you add a steady track of tone.

Below, each shot crossfades into the next. Here we were lucky because there was sufficient clean room tone within the handles of each shot to allow for easy crossfade creation. There’s no added, steady room tone track; instead, the room tone comes uniquely from the shots that make up the scene so it rarely has more than one source. “But,” you ask, “what about the crossfades? During these transitions two room tones are playing at once.” Yes, but as one shot fades in its partner fades out, so the sum of the two is never more than 100 percent of the average level of the shots. You haven’t broken the rule about avoiding more than one simultaneous tone.

Detail of preliminary edit of scene 45. Regions overlap more or less symmetrically and there’s no supplemental room tone track. The room tone for the scene is carried by the shots themselves.

Creating crossfades between regions doesn’t eliminate sound differences between shots. It merely lengthens the transition so that you don’t notice the changes as much. Human “hearing memory” is surprisingly short, so it doesn’t take much to fool the ear into thinking that a transition is smooth. Just spread the transition over a bit of time and most listeners won’t hear a thing.

Once you construct smoothing crossfades between shots, the scene will almost certainly sound quieter, as though you equalized or otherwise cleaned it. There will likely remain “swells” as you move back and forth between shots. When the room tone characteristics of two adjacent shots are very different, there’ll be peaks and troughs in the overall noise level as well as changes in the sound itself. This brings us to the next basic rule of dialogue editing.

Rule Two: Evenness is a Trade-off Between Noise and Smoothness

When two shots don’t match well, you’ll inevitably hear their transitions despite crossfades. By lengthening a crossfade, you’ll smooth the transition and give the impression of evenness. At the same time, this will increase the total noise since there’ll be a longer period during which two room tones are playing. What’s the “right” length? Of course, there’s no answer to that. It’s a choice, so use your judgment. Don’t be afraid to experiment with fade lengths; a tiny change in overlap can make a huge difference in balance, noise, and smoothness of the crossover. Plus, the two fades that make up a transition needn’t be symmetrical. Typically, the noisier of the two room tones will require a longer overlap and longer fade, since it’s carrying more energy—your hearing needs more time to adapt (see below).

The louder side of a crossfade will require more time to lose and gain energy, and normally will require a longer fade.

Rule Three: Design Scenes That Require the Least Amount of Processing

An edit that will already play smoothly allows the mixer to use less processing, less camouflaging, and makes the predub/mix less of a technical endeavor. As a mixer you don’t want to have to battle the edit, but rather to finesse it and focus more on the artistic vision of the director.

–   David Barber, MPSE, rerecording mixer, supervising sound editor House at the End of the Street

While it’s true that you can smooth almost any shot transition if you throw enough EQ and noise reduction at it, you have to ask yourself, “At what cost?” Scenes not properly prepared prior to the mix require much more processing to achieve an acceptable amount of smoothness. Because of the excessive filtering they may lack life, or sound thin and metallic, or at worst like a cell phone.

When your transitions are smooth, they’re less objectionable to the ear. Hence, they require less shot matching. Of course, certain shots will need to be “helped along” and the entire scene may need noise reduction, but since your dialogue transitions largely take care of themselves, you don’t need to overcook it. This allows the rerecording mixer to put more energy into making the shots sound nice—robust, full, warm, articulate. The dialogue hasn’t been stripped of its character, so there’s more to play with.

Ironically, the noisier the location of the scene, the bumpier you can leave your dialogue edit. If you’re cutting a scene with lots of traffic noise, in a location where traffic is logical, rest assured that the sound effects editor can sort out a problematic dialogue transition with a well-placed car-by or other background motion effect. No one will notice one more car amid a noisy scene, and the tiny added motion energy will bridge the gap.

On the other hand, no scene is harder to cut than an intimate conversation in a dead quiet bedroom at three in the morning. There’s nothing to hide behind, and if the shots aren’t naturally well matched, it’s a nightmare to cut back and forth. If there’s camera noise on one shot but not on the other, you have very few smoothing resources and you can’t count on the SFX guys to save you. There are few appropriate atmospheric sound effects that can be used to mask the bumps, so you’re on your own. Hopefully, you will have a few mics to choose from.

E xcerpt from Dialogue Editing for Motion Pictures: A Guide to the Invisible Art, 2nd Edition by John Purcell © 2014 Taylor and Francis Group. All Rights Reserved.

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