在下是在這個PDF說明檔上看到的:
http://www.sigmadesigns.com/products/rmMPEG-4codec.pdf
其中有一欄Interlaced Video Encoding Tools

Intelligent Deinterlacing
Deinterlacing is a technique that uses a pre-processing filter to convert interlaced
video into progressive video. It removes jagged-edge artifacts in moving objects on
interlaced video. Deinterlaced video performs well on non-interlaced monitors. If the
source video is progressive, this option should remain disabled. Interlaced Video
Encoding Tools REALmagic MPEG-4 Video Codec fully supports interlaced video encoding.
Interlaced video is most commonly found in material intended for TV broadcast.
For interlaced video, a “field” is the assembly of alternate lines of a frame.
An interlaced frame is composed of two fields: top and bottom. Each line of the
top field is spatially located immediately above the corresponding line of the
bottom field. In an interlaced frame, one of these two fields must display first,
and is labeled the first field. The first field can be the top field or the bottom
field of the frame. If interlaced video encoding is selected, the user must specify
whether the top field is displayed first.
In some cases, using alternate vertical scan generates better quality. REALmagic
MPEG-4 Video Codec provides this tool to improve interlaced video encoding quality.
Alternate vertical scan needs decoder support. The REALmagic Xcard fully supports
this function.
Depending on your decoder, header information may cause compatibility issues
during playback. The REALmagic Xcard supports RMP4, DX50, and DIVX.

Q: Why do I need to use deinterlacing?
A: Deinterlacing is not required; REALmagic MPEG-4 Video Codec fully supports interlaced
videoencoding. However, to play your video on a non-interlaced (VGA) monitor from an
interlaced videosource, deinterlacing improves playback quality by removing jagged-edge
artifacts in moving objects of interlaced video. Deinterlacing, by its nature,
is a lossy process.