AfterEffects

Separate video fields

If you want to use interlaced or field-rendered footage (such as NTSC video) in an After Effects project, you will get the best results if you separate the video fields when you import the footage. After Effects separates video fields by creating a full frame from each field, preserving all of the image data from the original footage.

Separating fields is critical if you plan to make significant changes to the footage. When you scale, rotate, or apply effects to interlaced video, unwanted artifacts, such as crossed fields, are often introduced. By separating fields, After Effects accurately converts the two interlaced frames in the video to noninterlaced frames, while preserving the maximum amount of image quality. Using noninterlaced frames allows After Effects to apply edits and effects consistently and at the highest quality.

After Effects creates field-separated footage from a single formerly interlaced field by splitting fields into two independent frames. Each new frame has only half the information of the original frame, so some frames may appear to have a lower resolution than others when viewed at Draft quality. When you render the final composition, After Effects reproduces high-quality interlaced frames for videotape. When you render a movie at Best quality, After Effects interpolates between the scan lines of a field to produce maximum image quality.

If your output will not be interlaced, it's best to use noninterlaced source footage, to avoid the need to separate fields. However, if a noninterlaced version of your source footage is not available, interlaced footage will work fine.

When you render a composition containing field-separated footage, set the Field Rendering option to the same field order as your video equipment. If you don’t field-render the composition, or if you field-render with the incorrect settings, the final movie may appear too soft, jerky, or distorted.

To very quickly give video footage a more film-like appearance, import the footage twice, and interpret each footage item with a different field order. Then add them both to the same composition and blend them together. The misinterpreted layer will add some film-like blur.

After Effects automatically separates fields for D1 and DV video footage items. You can manually separate fields for all other types of video footage in the Interpret Footage dialog box.

  1. Select the footage item in the Project panel.
  2. Choose File > Interpret Footage > Main.
  3. Choose an option from the Separate Fields menu.
  4. Click Preserve Edges (Best Quality Only) to increase image quality in nonmoving areas when the image is rendered at Best quality. Then click OK.
    Note: If the field settings in the Interpret Footage dialog box are correct for the input footage and the field settings in the Render Settings dialog box are correct for the output device, you can mix footage items of different field orders in a composition. If either of these settings is incorrect, however, the frames will be in the correct order, but the field order may be reversed, resulting in jerky, unacceptable images.