What is progressive scan?
One of the primary tasks of the MPEG decoder inside every DVD player is to take the 24 fps data stored on the DVD and convert it to 60-fields-per-second video for TV viewing. Since 24 doesn’t divide evenly into 60, a process called “3-2 pulldown” is employed, where 3 video fields are created from the first film frame, then 2 fields from the next frame, then 3, then 2, 3-2-3-2-3-2, etc. The result is 60-fields-per-second interlaced-scan video, and that’s the end of the story for non-progressive-scan DVD players. Progressive-scan DVD players add an important additional step to create a better-looking picture they generate a progressive-scan video signal through a process called de-interlacing (sometimes called “line-doubling”). The de-interlacer’s first task is to look at the interlaced video signal as it leaves the MPEG decoder and determine whether its original source was 24-frame-per-second film or 30-frame-per-second video. The original frame rate determines the type of processing ne
Progressive scanning is the ability to generate a picture in one pass (as with a computer monitor). Conventional interlaced scanning requires two passes to generate a picture, the first pass for the odd-numbered scan lines, the second for the even-numbered scan lines. Conventional analog TV as we know it is interlaced scanning with a (complete picture) refresh rate of 30 times per second, while progressive scanning is twice that at 60 times per second.
