Aiwa XD-SPM823 - Manual (Page 9)

ENGLISH
9
INTRODUCTION
En
General information on progressive scan
This unit includes a progressive scan conversion circuit. This generates high-resolution progressive scan video, with a lower
flicker rate, allowing you to see the movie at its original quality.
What is a progressive scan?
The conventional television system has 525 scan lines
making up a frame, but these are scanned in alternate
interlaced passes of the 262.5 odd scan lines and the 262.5
even scan lines (in the case of the NTSC color system).
Since its frame rate is 30 frames per second, one of these
passes, termed a field, occurs every 1/60 second. With
larger screens, since the whole screen is only refreshed
every 1/30 second, there can be noticeable flickers. In distinction to this, a progressive scan is one where all of
the lines are scanned successively in a single pass. By
saving a field in memory, it is possible to convert an
interlaced video signal to a progressive scan, which then
allows the image to be refreshed every 1/60 second,
reducing flickers on a large screen.
Advantages of progressive scan conversion in the DVD player
Conventional interlaced scan
(525 lines) Progressive scan
525 lines 262.5 lines
Scan of one field (1/60 second) Scan of whole frame (1/60 second)
Since the DVD player converts the video signal to a
progressive scan before digital-analog conversion, the total
number of conversions the signal undergoes is reduced,
compared with using a progressive scan conversion in the
television (see following figure). This reduces signal
degradation, and allows higher quality video playback.
Progressive scan conversion in the TV
Progressive scan conversion in the DVD player
Progressive
scan image
A/D ∗ 2 I/P ∗ 3 D/A
D/A ∗ 1
AV
decoder
AV
decoder
DVD player
DVD player
∗ 1: Digital-to-analog conversion
∗
2: Analog-to-digital conversion
∗ 3: Interlaced-to-progressive scan conversion
D/A I/P
TV