Sony DVP-NS999ES - Manual (Page 44)

ES Series DVD-Video/CD/SA-CD Players; Version 3.0 Page 44
Appendix A:
Progressive, interlace and DVD.
In video, what appears to be a continuously moving image is actually a
series of discrete still pictures, called frames. On the typical direct-view
television, each frame is created on the picture tube by an electron beam that
moves from the left edge of the screen to the right, illuminating one scanning
line at a time. The American EIA television system uses 525 total scanning lines
per frame. However, about 45 lines are consumed by the vertical blanking
interval and are not displayed on the screen. As a result, the EIA television
system is often called 480-line scanning.
Due to bandwidth limitations from the early years of television, the EIA
system was designed to capture 30 frames per second. The natural way to
display these images would be to show the scanning lines in sequence, an
approach called progressive scanning. 480-line progressive scanning at 30
frames per second is abbreviated 480/30P or 480P (when discussing the line
rate) or 30P (when discussing the picture rate).
Progressive scanning creates the picture by illuminating each line from
top to bottom until all scanning lines in the frame are completed.
Progressive images are clearer, and sharper. The horizontal scanning
lines are far less conspicuous.
Unfortunately, 480/30P creates flicker: the image visibly darkens between
frames. In addition, capturing images at 480/30P yields unsatisfactory results in
fast-paced action like live sports. For these reasons, the early television
engineers developed a solution called interlace scanning. Instead of capturing
and displaying all 480 lines in their numerical sequence, the EIA system divides
the image into two fields. The "A" field contains the odd-numbered scanning
lines (1, 3, 5, etc.) and lasts 1/60 second. The "B" field contains the even
numbered lines and lasts 1/60 second. This system can be abbreviated 480/60i