SDA9410
Preliminary Data Sheet
Motion compensation
motion compensated pixels will be different, and the chance that the non-motion
compensated field average at the output increases. The result is a graceful degradation
of picture material in case of vector failure (“local fall back mode”).
5-tap input,
can be changed by FILSEL
(non-motion compensated linear interpolation)
An
Bn
1/2 1/2
Median
bn
Figure 47
Principles of motion compensation for the ꢀ field (FILSEL=0)
To generate an output sequence with a good motion portrayal the estimated vectors and
the actual film mode information are used. Dependent on the film mode different output
sequences are generated. The standard mode is camera mode. In this mode the input
source provides a new motion phase on every field. The two other modes are called film
mode PAL and NTSC, respectively. The arise from scanning cinematic source material
for which only 24 frames per second are available. For film mode material scanned for
50 Hz standards always two successive fields have the same motion phase. The film
source is reproduced with 25 Hz and each image is scanned twice to get an interlaced
video signal. On NTSC film mode the 24 frames are scanned using the 2-3 pulldown
method resulting in sequences, which contain alternating two and three successive fields
with the same motion phase. In the next figures the three modes are illustrated for a one-
dimensional motion.
The aim on motion compensation is to create an output field or frame sequence, which
has a good motion portrayal. In the Figure 48, Figure 49 and Figure 50 the ideal motion
portrayal is displayed as a dashed line. The output motion (solid line) should approach
this ideal case. The deviation is marked as shadowed area. On camera mode no motion
blurring occurs on source material (Figure 48: square curve). A simple non motion
compensated scan rate conversion repeats previous motion phases and causes a
motion blurring on 100/120 Hz output dependent on motion speed (Figure 48: triangle
101
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