Pyro Industries API-1394PCI Instrukcja Użytkownika Pobierz pdf (Strona 268)

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■ MOTION EFFECTS

Motion Effects Interpolation

Each motion effect can be interpolated in different ways. Interpolation determines how

frames and fields will be blended, combined, or displayed in the motion effect. Interpo-

lation can determine how good a motion effect will look when played back. In the past,

you might have noticed slow motion replays on television that look poorly constructed.

In the old days, we used fields when playing back slow motion. As a result, single fields

looked pretty awful when played back slowly. Currently, the entire frame is used if

modern equipment is utilized. For example, most major league sports use slow-motion

relays in full-field mode.

There are four different modes of interpolating motion effects (see Figure 7.2).

Some, as indicated, are not available for every type of effect. They are:

Duplicated Field A Duplicated Field interpolation method consists of taking one field

of a frame and duplicating it, which halves the resolution of the image. This method is

not recommended for broadcast, but works fine for single-field projects that are intended

for the Web, or in some cases, CD-ROMs.

Both Fields Selecting Both Fields uses both fields of the video frame. In some cases, this

method will work fine, but not for fast-moving action. Often there are artifacts that

develop from interfield motion. As a result, this type of interpolation could appear jittery.

Interpolated Field Interpolated Field uses both fields and blends them. To be more pre-

cise, it uses field one for the first field of video and then blends field one with field two

for the second field of video. Rendering an Interpolated Field motion effect is more

time-consuming, but it works better for shots with interfield motion. However, when

used with freeze frames, Interpolated Field might result in a softer image.

VTR-Style VTR-Style interpolation is used only on timewarp and motion effects and is

not available on freeze frames for reasons that will be obvious. A VTR-Style method of

interpolation emulates slow-motion playback on VTRs by shifting field information by

Figure 7.2 Selecting an

interpolation mode

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