Editor Jeff Groth worked with “Joker” director Todd Phillips on “The Hangover Part III” before landing the blockbuster drama starring Joaquin Phoenix.

You cut the film as consecutively as possible so you could see the progression of the character while you were still editing. Can you talk a little bit about that?

With a movie called “Joker,” you know quite solidly where you’re going to land at the end. So it was about how are we getting and moving forward to that? It’s [about] the progression from beginning to end. It starts in one particular place and ends in another; we always look and kind of see where we were in our timeline of Arthur [transforming into] Joker.

You were also able to cut the movie with some of the score rather than temp track — did that make a difference to the editing process?

It made a big difference. There were five or six songs that came before we ever started shooting and those definitely influenced shooting as well as what I was doing. There’s a certain rhythm that was coming in off of those tracks, and [gave a good] feel for any given moment.

What techniques did you use to capture Arthur Fleck’s transformation into Joker?

It’s not so much a technique; we just would kind of let things play. [Joaquin Phoenix] has an amazing ability to transform his face and transform his body — the transformation happened in just about every shot in the scene. We tried not to overly manipulate some of that and would even go back in and kind of remove cuts from certain things just to make sure that you could witness what Joaquin was doing. Just making sure that reactions and scenes were consistent across, the whole movie is kind of tightening the screws in, letting out the leash on Joker.

How did you alternate between the close-ups and wider shots in terms of capturing the Joker?

[Phoenix] has got his whole body engaged in this thing. There’s times when you need to see him from a larger perspective; we’re showing things that are having physical effects on [him]. And then when you’re close up, you can see the emotional pain. We also have a few fairly long shots where you’re watching it play out from a distance.

Joaquin had a lot of freedom to experiment on set, giving you a lot of choices. Did it make things harder for you or easier?

It probably made things harder. He played it in multiple ways, they were all good. We had a lot of options, so it was about building a context for any given thing. You’re taking your best guess and then you go back and reevaluate. You’re modulating between what’s appropriate for now. You just pick a place to start and then see how it goes. We’re experimenting in the cutting room.

There’s a lot of influence that was drawn from 1970s and early 1980s movies. How was that style applied to “Joker”?

There’s certainly [that influence] within production design and cinematography. Kind of going back to letting things play, we didn’t try to be overly manipulative of the performance. There’s a lot less editing, shots are held longer, you get to see things unfold in a single shot a little bit more. If you look at the titles, they have got a very kind of specific yellow that feels like it reaches back to that time a bit. What we did with those is to actually put them on film, and then scan them back in so that they don’t have a digital edge. And they kind of have this little bit of color bleed that you would get from optical printing titles, which they just don’t do anymore.