ADR, which stands for automated dialogue replacement, or automatic... There's a little vagueness about what it really means, but we just all say ADR. For... You can get into a situation, and almost every film gets into this, where either dialogue for a scene was recorded, but there's too much noise in the background and you have to replace it. Science fiction films are full of this, because the actors are on sets that're probably also almost always made of plywood, but you want to imagine that they're made out of molybdenum or some fantastic metal, and so footsteps, which sound, clunk, clunk, clunk, have to be replaced, and that means you have to replace the dialogue as well. And so you get the actors in, after the film has been edited together, and you say, 'We want you to say these lines of dialogue again.' So there's nothing wrong with their performance, but it's just... Technically, it was very difficult to get a clean recording.

At the other end of the spectrum, there are times where you need to change the dialogue so that people understand the story better. For some reason, the dialogue as written doesn't work anymore because, who knows? You drop the scene, and now that dialogue doesn't mean anything because that scene is gone, so we have to change that scene. So, even though, in that case, the dialogue was recorded perfectly well, we have to replace it because we're now... we've written new dialogue, and we have to very carefully infiltrate the new dialogue, sometimes, into mouths that are not saying exactly those words.

Of course, this is what happens all the time when you make a foreign version of a film. A film... the actors may be speaking English, but now we're making the French version, and we have to fit French words, artistically, as closely as possible, into these mouths, and you can never do a perfect job of that, because it's not true. On the other hand, you can do it so that it is not gratingly obvious what's going on. So, if you imagine a full spectrum, from the technical problems with the recording of the dialogue to wholesale replacement of... reinventing the whole basis for a scene, that's what an ADR supervisor will work with the director to achieve.

And it's very tricky because you can never exactly tell how the actors are going to respond to this. Some actors, who are very talented actors on camera and even on stage, are not very good at ADR, because it's a completely artificial thing. You're looking at something that you acted in, perhaps, six months or eight months earlier, and you're trying to get back into that moment, and you may have done three other films in between... 'What was this?' And then you have to be very exact about how you say the lines of dialogue. And that particular skill is... It's a skill, kind of, like being able to stick your tongue out and turn it upside down; some people have it, and some people don't. It's just... You can never really predict how it's going to turn out. So there's a lot of very delicate handling of actors in, sometimes, fraught situations. There's a classic scene in... What's the name of that film? With Gene Kelly, where the whole idea is dialogue has to be replaced, and the actor has a nervous breakdown trying to replace the dialogue. So it's... Anyone familiar... If you've made a movie, you know the angst that surrounds this situation.