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AN-1256
APPLICATION NOTE
One Technology Way • P. O. Box 9106 • Norwood, MA 02062-9106, U.S.A. • Tel: 781.329.4700 • Fax: 781.461.3113 • www.analog.com
Manual Scaling in the ADV7186
by Edwin Omoruyi
Rev. 0 | Page 1 of 4
INTRODUCTION
Video decoders capable of video signal processing are in high
demand with video product consumers for three reasons. The
first reason is the ability to produce output resolution that is
completely different from the input resolution provided at
source. The second reason is the ability of the signal to pass
through the input video resolution unaltered. The third reason
for this high demand is the ability to eliminate ringing or
blurring in the output video data.
Scaling is the technique used to alter video resolution input at
the output. Changing to a much higher video output resolution
using a low video input resolution is upscaling.
Downscaling is the ability to modify high video input resolution
to a lower output video resolution to satisfy the backend device,
such as panels (like LCDs, for example), without the need for
external memory.
This application note describes the automatic and manual
scaling algorithm in the ADV7186 focusing primarily on
manual scaling. This application note only considers standard
input video formats.
HOW DOES SCALING WORK?
The ADV7186 is a video decoder with video signal processing
capability that offers upscaling/downscaling of the input video
resolution while eliminating ringing and blurring of video
data. The ADV7186 includes an Analog Devices, Inc., Scaler
Algorithm that provides very high quality video at the output
using only internal memory.
The scaling of the input video to the desired output resolution
is shown in the block diagram in Figure 1. The input video
could be NTSC or PAL video input or possibly a progressive
video input fed to the scaler block in the ADV7186. For the
NTSC/PAL input, the de-interlacer block provides the video
data to the scaler block. For the progressive video input, the
de-interlacer block is not used; instead, the path of the video data
is through the scaler block.
11771-001
DE-INTERLACER
(INTERLACED TO
PROGRESSIVE)
SCALER
Figure 1. ADV7186 Video Signal Processing Simplified Schematic
