Questions about TV lines of resolution

Archived from groups: alt.tv.tech.hdtv (More info?)

(1) OK, here's a really elementary question, but one that perplexes me. I
am sure many of you understand this perfectly and can clear up my confusion.

Quote from the NBC website FAQ page on their HDTV:

"The 720p format makes a picture with 720 vertical lines, each with 1280
pixels horizontally -- so in computer terms, it has a resolution of "1280 X
720". A similar statement is made about the 1080i format, with different
numbers, of course.

"720 vertical lines" sounds as though, starting from left and counting to
right, there are 720 lines of pixels, lines going from top to bottom -- top
to bottom being the definition of a "vertical line", right? Then, they say
each line is made up of 1280 pixels. That sounds to me as though the
picture, then, would be 720 pixels across (one for each line) and 1280
pixels up (the number IN each line). But that gives us a picture that has
fewer pixels across its wide expanse than it does in its much narrower up
and down dimension, which does not seem rational.

So, by "vertical lines" do they actually mean "horizontal lines" stacked up
vertically? Or do they mean what they say?

(2) Here's something else they say on this page:

"...movies and many primetime shows that are produced on film are made with
only 24 pictures per second, so 1080i actually becomes progressive scan when
film-based material is being broadcast!"

How could that be? TV is 30 frames per second. Movies are shot at 24
frames per second. When you translate movies to TV or show a TV screen in a
movie, you have to electronically compensate for this. It doesn't make any
difference how many frames per second the movie was orginally shot in -- the
TV version is going to be 30fps, because that's what TV is. Have I missed
something here? If so, please educate me.

mack
austin

Archived from groups: alt.tv.tech.hdtv (More info?)

"Mack McKinnon" <MckinnonRemoveThis@tvadmanDeleteThisAsWell.com> wrote in
message news:3WC3d.9745$Gn3.4348@fe2.texas.rr.com...
> (1) OK, here's a really elementary question, but one that perplexes me. I
> am sure many of you understand this perfectly and can clear up my
> confusion.
>
> Quote from the NBC website FAQ page on their HDTV:
>
> "The 720p format makes a picture with 720 vertical lines, each with 1280
> pixels horizontally -- so in computer terms, it has a resolution of "1280
> X
> 720". A similar statement is made about the 1080i format, with different
> numbers, of course.
>
> "720 vertical lines" sounds as though, starting from left and counting to
> right, there are 720 lines of pixels, lines going from top to bottom --
> top
> to bottom being the definition of a "vertical line", right? Then, they
> say
> each line is made up of 1280 pixels. That sounds to me as though the
> picture, then, would be 720 pixels across (one for each line) and 1280
> pixels up (the number IN each line). But that gives us a picture that has
> fewer pixels across its wide expanse than it does in its much narrower up
> and down dimension, which does not seem rational.
>
> So, by "vertical lines" do they actually mean "horizontal lines" stacked
> up
> vertically? Or do they mean what they say?
>
> (2) Here's something else they say on this page:
>
> "...movies and many primetime shows that are produced on film are made
> with
> only 24 pictures per second, so 1080i actually becomes progressive scan
> when
> film-based material is being broadcast!"
>
> How could that be? TV is 30 frames per second. Movies are shot at 24
> frames per second. When you translate movies to TV or show a TV screen in
> a
> movie, you have to electronically compensate for this. It doesn't make
> any
> difference how many frames per second the movie was orginally shot in --
> the
> TV version is going to be 30fps, because that's what TV is. Have I missed
> something here? If so, please educate me.
>
This should help.

http://www.hometheaterhifi.com/vol [...] -2000.html


> mack
> austin
>
>
>
>

Archived from groups: alt.tv.tech.hdtv (More info?)

>>It doesn't make any> difference how many frames per second the movie was
orginally shot in --
> the > TV version is going to be 30fps, because that's what TV is.<<
Think again.
The ATSC standard provides for 24, 30 & 60 frame per second rates. You're
confusing the old NTSC standard with the new ones. Let it go!!



"Mudd Bug" <muddbug@cox.net> wrote in message
news:kbJ3d.44846$Ka6.8177@okepread03...
>
> "Mack McKinnon" <MckinnonRemoveThis@tvadmanDeleteThisAsWell.com> wrote in
> message news:3WC3d.9745$Gn3.4348@fe2.texas.rr.com...
> > (1) OK, here's a really elementary question, but one that perplexes me.
I
> > am sure many of you understand this perfectly and can clear up my
> > confusion.
> >
> > Quote from the NBC website FAQ page on their HDTV:
> >
> > "The 720p format makes a picture with 720 vertical lines, each with 1280
> > pixels horizontally -- so in computer terms, it has a resolution of
"1280
> > X
> > 720". A similar statement is made about the 1080i format, with
different
> > numbers, of course.
> >
> > "720 vertical lines" sounds as though, starting from left and counting
to
> > right, there are 720 lines of pixels, lines going from top to bottom --
> > top
> > to bottom being the definition of a "vertical line", right? Then, they
> > say
> > each line is made up of 1280 pixels. That sounds to me as though the
> > picture, then, would be 720 pixels across (one for each line) and 1280
> > pixels up (the number IN each line). But that gives us a picture that
has
> > fewer pixels across its wide expanse than it does in its much narrower
up
> > and down dimension, which does not seem rational.
> >
> > So, by "vertical lines" do they actually mean "horizontal lines" stacked
> > up
> > vertically? Or do they mean what they say?
> >
> > (2) Here's something else they say on this page:
> >
> > "...movies and many primetime shows that are produced on film are made
> > with
> > only 24 pictures per second, so 1080i actually becomes progressive scan
> > when
> > film-based material is being broadcast!"
> >
> > How could that be? TV is 30 frames per second. Movies are shot at 24
> > frames per second. When you translate movies to TV or show a TV screen
in
> > a
> > movie, you have to electronically compensate for this. It doesn't make
> > any
> > difference how many frames per second the movie was orginally shot in --
> > the
> > TV version is going to be 30fps, because that's what TV is. Have I
missed
> > something here? If so, please educate me.
> >
> This should help.
>
>
http://www.hometheaterhifi.com/vol [...] -2000.html
>
>
> > mack
> > austin
> >
> >
> >
> >
>
>