On Thu, 25 Apr 2002 21:48:16 GMT, Erik Harris wrote:

>I've been wondering about this for awhile, and none of the literature I've
>seen on the advantages of progressive scan specifically addresses this.. Do
>NTSC progressive scan devices (TV's, DVD players, etc) operate at 60 frames
>per second or 30 frames per second? It seems that to derrive any real
>advantage from displaying 480i signals in 480p mode, you'd need to run at
>60fps, with each field being converted into a frame. Otherise, at 30fps,
>you're gaining the progressive picture clarity and some interpolated
>"detail", but you'd be halving the time-domain resolution of the video. It
>seems that losing half of the time-based information would impact the video
>more than taking away the flicker and adding some interpolated spatial
>clarity. This leads me to assume that they'd probably operate at 60fps, but
>nothing I've read thus far (on-line, in magazines, in specs for TV's, etc)
>has given me anything to go on other than my own assumption.

Perhaps best to start from "0", rather than answering specific points...
- PS-mode/"frame-mode" operates at 30fps for Canon cameras,
15fps for Sony, but the Canon interpolates fields to get
the higher frame rate, reducing spatial resolution (which
in any case cannot be greater than it is for interlaced
video...); the Sony retains the spatial resolution of the
frames by sacrificing even more of the temporal resolution
that PS-mode reduces by halving the 60fps field rate.
- The increased temporal (never spatial...) resolution
derived from PS-mode use is realized only with compatible
display (grabbed stills, computer-monitor use, etc.).
- Since most TVs are interlaced displays, using PS-mode for
these is generally inappropriate, though some people
appear to like the resultant "flicker" for reasons totally
mysterious to me...;-)
- True frame mode for NTSC video, if it were appropriate
(it is for computer monitor display), would be at
30fps - though PAL 25fps approximates film's 24fps, making
film transfers possibly easier. The new Panasonic 24fps
frame-mode camera looks interesting for those who intend
to do film transfers - but film transfers from video are
quite expensive, and it is unlikely the average user
would routinely transfer the video footage to film...