View Full Version : Progressive scan vs. interlaced HDTV

07-19-2006, 03:50 AM
I am familiar with NTSC video, being from the USA. I currently use
standard NTSC video for motion analysis using the Peak Motus motion
analysis system. The "picture rate" after deinterlacing the video is 60
Hz (30 frames each containing 2 interlaced fields). Because of the
interlacing, however, the vertical resolution is limited. Hence I have
been watching the development of HDTV and HD camcorders. All the big
buzz among HDTV consumers is whether to buy the highest resolution HDTV
sets, those that have a 1920 x 1080 pixel resolution and can display
this resolution in progressive scan (i.e., 1080p) mode. A Google search
of "1080p HDTV" mainly revealed comparisons of how the screens looked.
As a biomechanist, however, I am more interested in frame rate than
screen resolution. Hence, my questions are the following: (1) What is
the full frame rate of the 1080p HDTV specification; is it 30 Hz or 60
Hz--or something else? (2) What is the full frame rate of the 1080i
(i.e., interlaced) HDTV specification?

The reason I ask is that I assume video signals for the 1080i and 1080p
specifications could each be captured and saved onto a computer hard
drive. The interlaced signal could be de-interlaced and the individual
fields saved. I assume there would be 60 separate fields per second
that could be viewed later (and presumably analyzed for motion analysis
purposes at 60 Hz) just like with normal NTSC video (i.e., 480i). Is
this true? If we did the same thing for the 1080p signal, would we have
60 full frames per second saved to the hard drive--or only 30? If the
answer is only 30 then this new 1080p specification is of very limited
use for a biomechanist.

Any help from those with experience with HD 1080i camcorders or 720p,
1080i, or 1080p HDTVs would be appreciated.



Richard N. Hinrichs, Ph.D.
Department of Kinesiology
Arizona State University
P.O. Box 870404
Tempe, AZ 85287-0404
(1) 480-965-1624 (phone)
(1) 480-965-8108 (fax)
hinrichs@asu.edu (email)
www.public.asu.edu/~hinrichs (personal website)
www.asu.edu/clas/kines (dept. website)