Join Richard Harrington for an in-depth discussion in this video Correctly interpreting fields and frames, part of Adobe Green-Screen Workflow (2013).
Once you bring footage into your project, you may need to properly interpret it. There's lots of potential issues. You can have things like non-square pixels, which are pretty common in professional video cameras, and in this case you might need to properly flag the footage so it displays the correct frame size. You also could have issues with things like fields. Maybe it's older footage that was shot interlaced, or standard defintion. You might need to flag those fields and tell them how to be interpreted. Let's take a look at the settings inside Premier Pro to do just that.
I've got my imports here, and I have a clip called par, let's press the tilde key here to go back to the normal layout. And I'm going to double-click that clip to load it. You'll notice that it's currently distorted. This clip came from a non-square pixel source, however, it's not displying correctly. I'm going to go ahead and turn on my preview area here. And I see that this clip is displaying it. At 1440 by 1080. Well, that's a very standard size when dealing with DVC Pro Source footage.
I'll go ahead and right-click on that clip. And choose modify interpret footage. This allows me to come down, and I can either check to make sure that the exact pixel aspect ratio is assigned. In this case, the file did have it inside. Or, I could use the conform menu, and assign the correct option. You see that that's going to work here.
A pixel aspect ratio of one point three, three, and when I click OK, the footage takes on the proper 16 by nine appearance that you'd expect. All right, the next shot I'm going to work with here is fields. I highly recommend when shooting your green screen footage that you choose to shoot progressive. Fields will not come in handy however, many folks do end up shooting in interlaced, either because it's the only thing that their camera gives them the choice, or out of habit. Here's how to go ahead and make sure that those fields are properly interpreted or ignored inside Premiere.
With the clip selected here, you'll notice that it says that it's lower field first. That's because this is a standard definition key source. If this was HD and recorded interlace, it would likely be upper field first, which is more common. I can go ahead and right-click and choose to modify Interpret footage. Now within this here, you'll see that you have the ability to choose either using the fields as set in the original file or choose to conform.
You could choose upper or lower if the field order got reversed, or force it to interpret as a progressive file. Notice that that does modify then how the footage behaves. And in this case it's going to treat it as a progressive file, essentially ignoring the fields. Now, being able to take this type of control is important because sometimes your footage will not come in correctly. Now that I've got it set properly, I can easily copy and paste right from Premier Pro into an after-effects project.
But I also want to quickly show you how these same settings are available in After Effects if you find that the footage hasn't been properly interpreted. I've got the same two clips over here in my project and you see that clicking on it gives you similar information. Let's start with the pixel aspect ratio here, and I'll double-click to load that clip, and it definitely looks distorted. By right-clicking, I could choose interpret footage main.
And this gives me the ability to assign the correct pixel aspect ratio. There we go. And I double-clicked. Now, the clip updated here in the project but if you don't see it update inside the preview window here for the footage, just go ahead and click the Pixel Aspect Ratio Correction button and you'll see it adjust. Here's the fields as well. Let's open that up. And I can see that that's currently being treated as interlaced material. If I right-click and choose Interpret Footage, Main, this gives me the ability to go ahead and turn the fields off.
We do have a slight change, and it's a cleaner edge now that we're interpreting that interlace material, forcing it to be progressive. Once you understand how to properly interpret frame size and fields, you'll be able to deal with any footage that doesn't import correctly. Now, this isn't just a process for when you're getting ready for post-production. It actually can be used on set as well.
This course was created and produced by Rich Harrington. We're honored to host this material in our library.
- Deciding where to key your footage: Premiere Pro or After Effects
- Importing footage to key
- Stacking layers in Premiere Pro
- Using the Ultra Keyer
- Using KEYLIGHT
- Enhancing a key with 3D lights
- Deciding when to use a third-party tool
- Processing backdrops in Photoshop
- Exchanging transparency data