Progressive frames are captured in their entirety - the entire frame.

Interlaced files are captured in alternating horizontal lines - so each "frame" has "half" the data of a progressive frame.

The diagrams here explain it very simply:

http://www.axis.com/products/video/camera/progressive_scan.htm

INTERLACED

PROGRESSIVE

Noah's answer is certainly a good start. If you want more detail, I provide it on this page, along with links to some other even deeper technical resources.

Here's an excerpt:

"In an interlaced system, only half the number of horizontal lines for each frame of video are transmitted at a time. Because of the speed of transmission, the afterglow of displays, and the persistence of vision, the viewer perceives each frame in full resolution. All of the analog television standards use interlacing. Digital television standards include both interlaced and noninterlaced varieties. Typically, interlaced signals are generated from interlaced scanning, whereas noninterlaced signals are generated from progressive scanning.

Each interlaced video frame consists of two fields. Each field contains half the number of horizontal lines in the frame; the upper field (or Field 1) contains the odd-numbered lines, and the lower field (or Field 2) contains the even-numbered lines. An interlaced video monitor displays each frame by first drawing all of the lines in one field and then drawing all of the lines in the other field. Field order specifies which field is drawn first. In NTSC video, new fields are drawn to the screen approximately 60 times per second, corresponding to a frame rate of approximately 30 frames per second."

yes, I can :-D



*but Noah did a good job at it too :)

thank you gents, very helpful. all the best.