Use the Interlace tool to convert a sequence of progressive frames to an output of interlaced video frames. Each pair of input frames result in one output frame.

To convert progressive frames to interlaced frames:

1. Select either NTSC or Non-NTSC from the Format menu.
2. Select the field order. If the upper field is first, then the upper field is taken from the first frame of the input pair and the lower field is taken from the second frame of the input pair; otherwise, upper and lower fields are reversed.

The output is always at the same frame rate as the input, and the action will play twice as fast. You can always use a Rate Convert node before the Interlace if needed. The following table shows how frames are interlaced. The input frames are numbered consecutively from 1 as shown in the top part of the table. Each output frame shows two numbers, which indicates the input frame indices for field 1 and field 2 respectively.