This is what 'GSpot' says about a recording I made from my pvr. The 'PROG' box indicates that it's 'progressive' http://www.afterdawn.com/software/video_software/video_tools/gspot.cfm
The "P" in 1080P means progressive. If you loaded a file into GSpot and size was 1080x480 (my example shows the pic size as 704x480) and the 'PROG' window was lit, you know it's 1080P. The size of the LCD TV (in North America) is 480 high and the programs are transmitted at various widths - 1080 wide for example. If your file was interlaced, the 'I/L' window would be lit up. In my area I pick up the local HD signal from the ABC station. It broadcasts one channel at '720p' 16:9 which fills the wide screen. It's sub channels ( weather and oldies) are '480i' 4:3 which looks like the traditional TV picture.
