Testing the field-rendering order

A simple test can determine the order in which your video equipment requires fields. When you make a movie, the rendering order (Upper Field First or Lower Field First) should be synchronized with the method used by your equipment, or your movie will appear distorted.

Note: The field order with which you record to video equipment can be altered by changes in the hardware or software of your production setup. For example, changing your video board, device control software, or VCR after setting the field order can reverse your fields. Therefore, any time you make a change to your setup, run this test for field-rendering order.

The test takes about 15 to 20 minutes and involves creating two movie versions of the same composition (one rendered with Upper Field First and one with Lower Field First), and then taping and playing the movies to see which choice looks right.

To test field-rendering order:

1. Create a simple composition with the correct frame size and frame rate. Choose an NTSC or PAL preset in the Composition Settings dialog box, and make the composition at least 3 seconds long.
2. Within the composition, make a layer that is a small rectangular solid. The layer can be any color as long as it contrasts sharply with the composition background. You may wish to add a title such as "Upper Field First" to the solid, to make identification of the movie easier.
3. Apply some fast movement to the solid using keyframes in its Position property. Set keyframes from the upper left of the Composition window to the lower right, for 1 second.
4. Save the project, and then drag the composition to the Render Queue window.
5. Click the underlined Render Settings name, and then choose Upper Field First.
6. Click OK, and then click Render to make the movie.
7. In the composition, change the color of the solid in the Composition window, and add a new title such as "Lower Field First" to identify it.
8. Render the composition again, choosing Lower Field First.
9. Record both movies to videotape with the same device.
10. Play both movies.

One movie will look distorted and have jumpy horizontal motion or shape distortion during vertical motion. The other movie will play back smoothly, with sharply defined edges. Use the field order that you used to create the smooth playing movie whenever you render movies with that particular hardware configuration.