The Art of the Fix: Film Audio
Published on Dec 10, 2013 by Christine Janesko
Artists and technicians who work in sound for film, photography, filmmaking, and recording all know one thing to be true: almost nothing comes out perfect. To create that ‘perfect’ audio track, photo, on-screen explosion, or song often requires some altering of reality – also known as post-production.
When most people go to the movies, what they don’t realize is that nearly every sound in the film they’re watching and listening to has been separately produced and added in. In fact, the only sound that is captured on set is the dialogue.
“When they’re on set, and they’re shooting a movie, the number one thing – the only thing – that matters sound-wise is the dialogue performance,” says Skywalker Sound Re-Recording Mixer Juan Peralta. “That sound recordist – that’s their job, that’s what they’re going to try to get. Getting that performance is key.”
While a film’s sound designer and his team produce all the other sounds in the film – explosions, car engines, footfalls, even wind – an actor’s voice and performance is captured on set. However, sometimes even that one recording can go wrong. For instance, says Juan, maybe the boom operator was just a bit too far away (and the dialogue is too faint), or you can hear the camera noise in the dialogue track, or there’s an audible buzz from the set lights, or the hum of a generator.
That’s where ADR (automated dialogue replacement) comes in. Basically, an actor comes to the studio and records the unusable lines again, and the new recording is patched over the old recording. Sound simple? Not exactly, says Juan.
“After they record it, the dialogue editor gets it and they sync it to the picture. They cut it and make sure it matches everything and they make sure it’s going to replace the production dialogue perfectly, so the lips match and everything,” says Juan. “Then they give it to me, and now it’s my job to give it the same reverb, the same space, the same noise that was there,” he explains.
If the dialogue was recorded on a beach or in a forest, the same ambient background noise must be added back in to the recording. Otherwise, the edit will be obvious to the audience.
“The [actors] could be in a car, and the car could be moving and a window could be open, and you have ‘vrmmmm’ all this noise, and then you cut to ADR, and it’s just this nice, beautiful, clean recording with nothing – it’s crystal clear – and then you go back to the car, ‘vrmmmm.’ It can sound very different – miles apart,” says Juan.
To add the ambient noise back into the ADR recording, typically Juan will take a sample of the ambient noise from another part of the recording.
“We find a little piece of air where they’re not talking, grab that, and kind of loop it and create a longer file, and put that right under the lines, so that it feels like it’s all part of the same scene,” says Juan.
Although this is only one part of Juan’s job as a re-recording mixer (he also is responsible for creating the final mix of all the sounds, including the surround sound mix), it’s an important one to keep the continuity of the film.
“You have to make it seamless,” says Juan. “You have to make it inaudible. You just [want the audience to] buy it: ‘Oh, yeah, that’s what they said.’ But in reality, we replaced the line, and we changed it.”