Interlaced vs Progressive?

[lnetzel]

What is it and how do I know what my movie has? (or is?)

[kinneera]

Interlaced video basically splits the video into two fields, which are rendered in two passes to produce the whole image. There are some technical details having to do with frequencies and such that are the cause for this, but the short of it is that the maximum scan height for NTSC is 240 lines, so to construct video with 480 lines, interlacing is necessary. I believe this discussion doesn't apply to PAL or SECAM. (Anyone who believes otherwise, feel free to chime in here).

So how do you know if video is interlaced? Basically, if its height is 480 and it is NTSC, it is probably interlaced. Otherwise it is likely progressive (i.e. videoCD at 352x240 is progressive, DVD at 720x480 is generally interlaced).

Of course, the easiest test is how it looks on your computer. Computer moniters handle interlacing poorly, and the artifacts will be fairly obvious.