Using interpretation rules

You can automate how After Effects interprets different types of imported footage. For example, each time you import a clip with unlabeled fields, you must specify the field separation order; but when you import dozens of clips, you can save time by using the interpretation rules.txt file, which handles this for you.

The interpretation rules.txt file defines how After Effects identifies and matches footage by using parameters for frame dimensions, frame rates, file type, and codec. If it finds a match for the footage you're importing, it then automatically sets the field order, frame rate, alpha channel interpretation, and pixel aspect ratio.

Ordinarily, the interpretation rules.txt file is stored in the same location as the application. You can modify this file to produce the custom rules file you need. Editing this file is straightforward if you follow the samples listed in the file. However, the more experience you have with scripting or related tasks, the more comfortable you'll feel editing this file. As a precaution, you might make a backup copy of the file before changing the original.

When you edit the interpretation rules.txt file, you must supply a four-character file-type code for each footage type or codec. If you don't know the file-type code for a file or codec in a project, press Alt (Windows) or Option (Mac OS) as you select the file in the Project window. The file's file-type code and codec code (if compressed) appear in the last line of the file description at the top of the Project window.

Note: Any changes to the interpretation rules.txt file take effect the next time you open After Effects. If After Effects is already open when you edit the rules, you must exit and reopen the application to activate the new rules.