What Is ADR in Film? Automatic Dialogue Replacement Explained

Imagine that you’re watching your favorite action film. Maybe there is a fight sequence or car chase happening yet every line of dialogue is perfectly audible over the sound of the action. How is this possible? Without ADR or Automatic Dialogue Replacement, it’s not. So what is ADR in film, why and how is ADR used, and how can the process be streamlined? Read on to find out!

Follow along with this tutorial using  RX  a powerful post production tool that helps you edit dialogue, remove background noise, and clean up your audio. 

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What is ADR in film?

ADR or Automatic Dialogue Replacement is just one phase of the post production process. This process replaces dialogue recorded on set with dialogue that is recorded in a studio afterward. ADR in film usually happens after the film is edited and after the dialogue editor has sifted through the on-set audio to determine a list of cues for the actors to perform. The actor or actors come to a studio to deliver lines which are then synced with the film. 

Why is ADR used in film?

ADR is used for a variety of reasons. Most often, ADR is done to get a cleaner recording of a line whether that is due to a technical reason such as background noise like a passing car, or for a creative reason such as to fix a performance. Typically ADR has to match the visual of the actor speaking but sometimes a director will opt to record new lines of dialogue to further the story along or to clarify a scene. You can get away with this if you can’t see the actor’s mouth such as when they’re turned away from the camera or if they are off-screen. 

How is ADR done?

First, the dialogue editor or sound editor will comb through the film and identify cues for ADR. These are sections where the on-set audio is not salvageable and need to be redone. The director will have likely noted some cues of their own during the video process where they’d like a different delivery of a line or places to add lines to enhance the story. 

Then the film’s actors will go to a recording studio or dubbing stage to record their cues. Usually the director or producer is present for this recording session to guide the actor’s performances. The typical workflow involves playing the video clip and original audio recording for the actor to rehearse along with to get the timing and emotional delivery right. Then the recording engineer hits record and the actor delivers the new version of the line while they listen to the original audio in headphones. I personally like to roughly edit the ADR as we work through cues so we know right away if something will sync together well. Once the director or producer is satisfied, we move on to the next cue until everything on the list has been done.

After the recording, the ADR is further refined in editing to blend seamlessly with the rest of the production’s audio. 

Watch David Barber walk through how he used iZotope’s RX Post Production Suite in post production to reduce background noise captured during the filming of Paper Spiders.

How to make ADR easier

There are some big challenges to consider when doing ADR such as changes in ambience or differences in microphone quality and tone that have to be addressed.

1. Match the EQ

Luckily, there are tools available such as Ambience Match and EQ Match in RX that help to match the ADR to the sonic character of the original audio. In this audio example, the last line of the dialogue was ADR and it didn’t have the low end that we hear in his earlier lines so I used EQ Match to get them closer together sonically.

Here's some quick steps for how to use EQ Match in RX: 

1. Open the EQ Match module
2. Make a selection in a file
3. Click Learn
4. Make another selection
5. Click Process

2. Match the ambience of the original recording 

When audio is recorded on set, the ambient sound or room tone is also in the background of those recordings. However, because ADR is done at a different location on a different day, the sounds of the environments are different and there will be audible shifts in ambience when cutting between original audio and the new ADR. iZotope’s Ambience Match is used to address this very issue by sampling ambience from one recording and applying it to another recording. 

In this audio example, the director wanted some additional dialogue between actors to set the scene. Since one of our actors is off camera during the scene, we had great flexibility in timing of his lines but it still needed to sound like he was in the same outdoor environment as his earlier lines. 

Here's how to get started with Ambience Match in RX: 

1. Open the Ambience Match module in the module list
2. Make a selection in a file
3. Click Learn
4. Make another selection
5. Adjust the Gain level as desired. The Gain control adjusts the level of synthesized ambience
6. Select Output Ambience Only if you want the selection replaced with only the ambience from the first selection
7. Click Render

For more on ambience-matching, check out How to Match Ambience for Film and TV with RX.

3. Reduce the number of ADR cues with background noise reduction tools

ADR in film can be a very tedious and time-consuming process. Using tools like RX to clean up original dialogue recordings can reduce the number of ADR cues by salvaging previously unsalvageable recordings. Modules like Spectral Repair can be used to remove intermittent background noise while Spectral De-noise works well to remove steady background noise.

For more on cleaning up different types of background noise for music and post production, visit How to Clean Up Audio and Remove Background Noise.

Start making professional ADR for film 

Now that you know why ADR is done and how the process works, you can take your audio quality up a notch by incorporating ADR into your next production. Avoiding common pitfalls like mismatched ambient sound and EQ will give you a more professional-sounding film.

While ADR for film isn’t a quick process it does give you a lot of control in the mix, which is always worth it in the end! And if you haven't already, try RX for free to get help make professional-sounding ADR in your productions.

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