RIVA128ZX datasheet(44/85 Pages) STMICROELECTRONICS

44 / 85 page

128-BIT 3D MULTIMEDIA ACCELERATOR

RIVA128ZX

44/85

Figure 44.

Displaying 2 fields with 1:1 ratio

The

RIVA128ZX video overlay handles interlaced

video by displaying every field, at the original frame

rate of the video (50Hz for PAL and 60Hz for

NTSC). The video scaling logic upscales

, in the ver-

tical direction

,the luma components in each field

and linearly interpolates successive lines to pro-

duce the missing lines of each field. This interpolat-

ed scale is applied such that the full frame size of

each field

is stretched to the desired height.

The video scaler offsets the bottom field image by

half a source image line to ensure that both frames

when played back align vertically.

The vertical filtering results in a smooth high quality

video playback. Also by displaying both fields one af-

ter another, any motion artifacts often found in dein-

terlaced video output are removed, because the pix-

els in each field are

displayed in the order in which the

original source was captured.

Line 10

Interpolated line

(Line 10 & 12)

Line 12

Line 11

Line 13

Interpolated line

(Line 11 & 13)

Frame 1 (Top field)

Frame 2 (Bottom field)

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