Aiwa XD-SPM823 General information on progressive scan, What is a progressive scan?

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.

Conventional interlaced scan (525 lines)

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.

Progressive scan

INTRODUCTION

262.5 lines

Scan of one field (1/60 second)

525 lines

Scan of whole frame (1/60 second)

Advantages of progressive scan conversion in the DVD player

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

DVD player

AV	D/A∗1
decoder

Progressive scan conversion in the DVD player

	DVD player
AV		I/P	D/A
decoder

	TV
A/D∗2	I/P∗3	D/A

En

Progressive scan image

∗1: Digital-to-analog conversion

∗2: Analog-to-digital conversion

∗3: Interlaced-to-progressive scan conversion

ENGLISH 9