Steve,
I was working from the assumption about the ~30fps comment that this was
about frames not fields. All SD UK TV is interlaced, with the exeption of
telecinied content.
NTSC content runs at 29.97fps, to stop strobing effects on the screen when
near lightbulbs on the US 30Hz mains.
On 19/11/2007, Steve Jolly <[EMAIL PROTECTED]> wrote:
>
> Brian Butterworth wrote:
> > If you are going to be pedantic, at least be right! UKTV (and all in
> > Europe) is 25 frames a second
> >
> > I suspect yuou don't understand what "interlaced" means.
>
> I think I detect an impending semantic argument, so let me try and avoid
> it. You're (I think) defining a frame to be the combination of as many
> sequential scans of an image (fields) as are required to build up a
> full-resolution two-dimensional picture. Two fields per frame, in the
> present case.
>
> Let me expand slightly: fields are often bundled together and called
> frames for broadcast purposes, although not necessarily in such a way
> that they form a combined image (eg two fields may be placed one above
> the other to form a frame for some MPEG treatments of interlaced
> material). Because of this, yes, you can describe 50 fields-per-second
> television as "25 frames-per-second". I would like to argue, however,
> that it is misleading to characterise an interlaced television system in
> terms of its frame rate.
>
> Why? Because each field comes from a different point in time, and
> combining them together leads to spatial ("combing") and temporal
> ("judder") artefacts. (There are exceptions to this rule, eg when each
> frame of a film is broadcast as two successive fields - in this case
> simple recombination of the fields does not necessarily result in these
> artefacts.)
>
> S
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--
Please email me back if you need any more help.
Brian Butterworth
http://www.ukfree.tv
