1080I / 720P

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"drs_retired" <drs_retired@earthlink.net> wrote in message
news:5Y6tc.12403$be.2907@newsread2.news.pas.earthlink.net...
> What is the difference between 1080i and 720P ?

1080 i = 1920x1080 pixels interlaced - interlaced means that every 1/30 of a
second, 540 of the pixels are displayed (the odd pixels) and the next 1/30
of a second the next 540 pixels are displayed (the even ones) - interlaced
like interdigitating the fingers of each hand

1080i is best for stuff that doesn't move very quickly like movies - worse
for sports
Almost everyone except ABC uses HD in 1080i

720p = 1280x720 pixels - progressive - means that the every 1/60 of a second
the TV displays an entire frame, the TV starts at line 1 and puts up the
next 719 lines in order - no interlacing.

720p is best for stuff that moves quickly like sports since the image
doesn't change in between the two (odd/even) half frames.
ABC uses 720P for everything

Most "consumer" HD TV's can not phyisically display much more than 720P,
limited either horizontally and/or vertically... the exceptions being very
high end rear projectors with 9" (or larger) tubes and a handful of really
expensive front projectors.

 

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Randy Sweeney (rsweeney1@comcast.net) wrote in alt.tv.tech.hdtv:
> 1080 i = 1920x1080 pixels interlaced - interlaced means that every 1/30 of a
> second, 540 of the pixels are displayed (the odd pixels) and the next 1/30
> of a second the next 540 pixels are displayed (the even ones) - interlaced
> like interdigitating the fingers of each hand

That's wrong.

The ATSC mode is 1920x1080/60i, so every 1/60th of a second, 540 lines are
displayed, and then 1/60th of a second later, the other 540 lines are
displayed.

Yes, the display of each field lasts 1/30th of a second, but you get new
information every 1/60th of a second.

--
Jeff Rife | "Hey, dogs guard.
SPAM bait: | Cats watch...and judge."
AskDOJ@usdoj.gov |
uce@ftc.gov | -- Salem the Cat

 

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"Jeff Rife" <wevsr@nabs.net> wrote in message
news:MPG.1b213d7531c4d1d998b440@news.nabs.net...
> Randy Sweeney (rsweeney1@comcast.net) wrote in alt.tv.tech.hdtv:
> > 1080 i = 1920x1080 pixels interlaced - interlaced means that every 1/30
of a
> > second, 540 of the pixels are displayed (the odd pixels) and the next
1/30
> > of a second the next 540 pixels are displayed (the even ones) -
interlaced
> > like interdigitating the fingers of each hand
>
> That's wrong.
>
> The ATSC mode is 1920x1080/60i, so every 1/60th of a second, 540 lines are
> displayed, and then 1/60th of a second later, the other 540 lines are
> displayed.
>
> Yes, the display of each field lasts 1/30th of a second, but you get new
> information every 1/60th of a second.

You are correct

I should have caught it when I said one field every 1/30 and the other the
next which would have given only 15 frames per second

thanks

 

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"Ron Malvern" <rmlvrn@nospam.com> wrote in message
news:MPG.1b1f13e39eea8545989709@news.gwtc.net...
> In article <c93k1c$2i5b$2@news.iquest.net>, toor@iquest.net says...
>
> > If you read the ATSC spec, you'll notice that the 1080i30 signal can
> > be sent to take advantage of the redundancy of the 1080/24p original
> > source. So, you can get some advantage from the redundancy in the
> > 24p originated material, yet transmit the signal in the 1080i30 format
>
> First of all, 1080i is not referred to as 1080i30. It's 1080/60i.

Says who? 1080i30 = 1080/60i

It's the same thing and the terminology is used both ways.

> Secondly it's commonly acknowedged that 1080/24p takes less bandwidth
> than does 1080i because of the greater compression efficiency of
> progressive scan.
>

 

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In article <CaJtc.28758$zO3.6131@newsread2.news.atl.earthlink.net>,
"FLY135" <fly_135(@ hot not not)notmail.com> says...
>
> "Ron Malvern" <rmlvrn@nospam.com> wrote in message
> news:MPG.1b1f13e39eea8545989709@news.gwtc.net...
> > First of all, 1080i is not referred to as 1080i30. It's 1080/60i.
>
> Says who?

Says the ATSC.

 

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"Ron Malvern" <rmlvrn@nospam.com> wrote in message
news:MPG.1b1f295911a5185098970b@news.gwtc.net...
> In article <c93pfp$2jil$1@news.iquest.net>, toor@iquest.net says...
> > In article <MPG.1b1f13e39eea8545989709@news.gwtc.net>,
>
> > I have seen it both ways. 1080i30 would be 30 frames per second.
> > This would be equivalent to 720p60 as 60 frames per second. Likewise,
> > I have also seen it with the inconsistent approach like you suggest,
> > where sometimes it is 'frames per second' and sometimes it
> > is 'fields per second.' I prefer using the same units all of
> > the time, where the number after the i/p is 'frames per second.'
>
> The number doesn't refer to frames per second. It refers to Herz, or
> cycles per second. And in this case, passes of the raster.
> Secondly "frames" don't exist in an interlaced system. All you have
> are "fields" that can't combine to make a frame, in spite of what you
> were told in high school. The fields can't match to make a frame since
> the fields are always exposed at different moments in time.

This is simply your re-interpretation of terminology. The fact is that two
fields of interlaced material has always been considered a frame and that
usage of terminology is ubiquitous. Just because it violates what you
consider to be the priniciple that all scans lines must be sampled at the
same point in time, doesn't mean that calling two fields a frame is wrong.
While your understanding of what fields are is correct, your use of
terminology is not.

 

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"Karyudo" <karyudo_usenet@yahoo.com.remove.me> wrote in message
news:6f2bb0p629dluk5ih2qkhkvmi2gu36cf10@4ax.com...
> On Wed, 26 May 2004 23:24:14 -0600, Ron Malvern <rmlvrn@nospam.com>
> wrote:
>
> >All you have
> >are "fields" that can't combine to make a frame, in spite of what you
> >were told in high school.
>
> False for film-based material.

You are disputing his argument incorrectly. It's a matter of accepted use
of the term frame does not include a specification that all fields be
sampled at the same point in time.

By using the film-based argument you simply are validating his belief that
frames must be sampled at one instance in time, which is exactly what film
based material does. This is not true. When speaking of material coded for
interlaced output, a frame is two fields. And when speaking of interlaced
capture a frame is still two fields.

>
> >The fields can't match to make a frame since
> >the fields are always exposed at different moments in time.
>
> False for film-based material.

Not entirely. 3:2 pulldown does combine two different film frames and
creates a true interlaced "source" image at regular intervals.

Also people should remember that interlaced material has two distinct
attributes. One is interlaced sampling of the source, which is common in
video. The other is interlaced display, which is required for NTSC (also
1080i, PAL, etc...) output. Progressive scan sampling of the source has a
completely different nature than interlaced sampling regardless of the fact
that they may both be played on an interlaced display.

 

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"Ron Malvern" <rmlvrn@nospam.com> wrote in message
news:MPG.1b21494f2397eb8098970d@news.gwtc.net...
> In article <CaJtc.28758$zO3.6131@newsread2.news.atl.earthlink.net>,
> "FLY135" <fly_135(@ hot not not)notmail.com> says...
> >
> > "Ron Malvern" <rmlvrn@nospam.com> wrote in message
> > news:MPG.1b1f13e39eea8545989709@news.gwtc.net...
> > > First of all, 1080i is not referred to as 1080i30. It's 1080/60i.
> >
> > Says who?
>
> Says the ATSC.

I didn't say that term 60i was incorrect. I'm saying that it is used both
ways. Although just 1080i is the most common.

 

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In article <m4Ntc.28949$zO3.21044@newsread2.news.atl.earthlink.net>,
"FLY135" <fly_135(@ hot not not)notmail.com> writes:
>
> "Ron Malvern" <rmlvrn@nospam.com> wrote in message
> news:MPG.1b21494f2397eb8098970d@news.gwtc.net...
>> In article <CaJtc.28758$zO3.6131@newsread2.news.atl.earthlink.net>,
>> "FLY135" <fly_135(@ hot not not)notmail.com> says...
>> >
>> > "Ron Malvern" <rmlvrn@nospam.com> wrote in message
>> > news:MPG.1b1f13e39eea8545989709@news.gwtc.net...
>> > > First of all, 1080i is not referred to as 1080i30. It's 1080/60i.
>> >
>> > Says who?
>>
>> Says the ATSC.
>
> I didn't say that term 60i was incorrect. I'm saying that it is used both
> ways. Although just 1080i is the most common.
>
I just did a quick scan of the spec, and didn't see the 'official
specification' of the 1080i30 (normal HDTV) vs. 1080i60 as being
normal HDTV. It makes much more sense to use the same units for
720p60 and 1080i30 as meaning that each pixel location is updated
at the 60Hz rate in the 720p example, and at the 30Hz rate in the
1080i example.

However, I have definitely seen both kinds of designation, and it
is usually pretty clear when someone has mixed the field and frame
update rates like 1080i60 vs. 720p60. If this was formally defined,
it makes MUCH MORE sense to use the same units --

<scanning-structure> [p | i ] <full-picture-update>

Frankly, I wouldn't see a need to 'correct' someone who used
consistent units, just as I wouldn't see a need to 'correct'
someone who used inconsistent units. In the scheme of things,
this designation isn't all that important, and cannot understand
the importance of strongly asserting a 'correction' that
only changes the kind of error .

As an engineer, I am loathe to mix units, and is why I personally
prefer the more consistent 1080i30 (for 30 frames per second) or
720p60 (for 60 frames per second.)

John

 

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"John S. Dyson" <toor@iquest.net> wrote in message
news:c98lrd$1021$1@news.iquest.net...
> In article <m4Ntc.28949$zO3.21044@newsread2.news.atl.earthlink.net>,
> "FLY135" <fly_135(@ hot not not)notmail.com> writes:
> >
> > "Ron Malvern" <rmlvrn@nospam.com> wrote in message
> > news:MPG.1b21494f2397eb8098970d@news.gwtc.net...
> >> In article <CaJtc.28758$zO3.6131@newsread2.news.atl.earthlink.net>,
> >> "FLY135" <fly_135(@ hot not not)notmail.com> says...
> >> >
> >> > "Ron Malvern" <rmlvrn@nospam.com> wrote in message
> >> > news:MPG.1b1f13e39eea8545989709@news.gwtc.net...
> >> > > First of all, 1080i is not referred to as 1080i30. It's 1080/60i.
> >> >
> >> > Says who?
> >>
> >> Says the ATSC.
> >
> > I didn't say that term 60i was incorrect. I'm saying that it is used
both
> > ways. Although just 1080i is the most common.
> >
> I just did a quick scan of the spec, and didn't see the 'official
> specification' of the 1080i30 (normal HDTV) vs. 1080i60 as being
> normal HDTV. It makes much more sense to use the same units for
> 720p60 and 1080i30 as meaning that each pixel location is updated
> at the 60Hz rate in the 720p example, and at the 30Hz rate in the
> 1080i example.

ATSC does use vertical scan frequency (i.e 60Hz) when describing the format.
It's not any kind of an official declaration of terminology to the extent it
could be cited to prove others wrong.

> Frankly, I wouldn't see a need to 'correct' someone who used
> consistent units, just as I wouldn't see a need to 'correct'
> someone who used inconsistent units.

Well this the important thing, especially in light of his insistance that
two fields of interlaced material don't make a frame. Which is clearly
incorrect.

> As an engineer, I am loathe to mix units, and is why I personally
> prefer the more consistent 1080i30 (for 30 frames per second) or
> 720p60 (for 60 frames per second.)

Yes but both 1080i and 720p are 60Hz. So it's a matter of what units you
are using. Vert scan or frames. Either way it's obvious as to what is
being refered to just by saying 1080i and 720p.

 

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In article <%t0uc.3676$Yd3.3467@newsread3.news.atl.earthlink.net>,
"FLY135" <FLY_135(@hot not not)notmail.com> writes:
>
> "John S. Dyson" <toor@iquest.net> wrote in message
> news:c98lrd$1021$1@news.iquest.net...
>> In article <m4Ntc.28949$zO3.21044@newsread2.news.atl.earthlink.net>,
>> "FLY135" <fly_135(@ hot not not)notmail.com> writes:
>> >
>> > "Ron Malvern" <rmlvrn@nospam.com> wrote in message
>> > news:MPG.1b21494f2397eb8098970d@news.gwtc.net...
>> >> In article <CaJtc.28758$zO3.6131@newsread2.news.atl.earthlink.net>,
>> >> "FLY135" <fly_135(@ hot not not)notmail.com> says...
>> >> >
>> >> > "Ron Malvern" <rmlvrn@nospam.com> wrote in message
>> >> > news:MPG.1b1f13e39eea8545989709@news.gwtc.net...
>> >> > > First of all, 1080i is not referred to as 1080i30. It's 1080/60i.
>> >> >
>> >> > Says who?
>> >>
>> >> Says the ATSC.
>> >
>> > I didn't say that term 60i was incorrect. I'm saying that it is used
> both
>> > ways. Although just 1080i is the most common.
>> >
>> I just did a quick scan of the spec, and didn't see the 'official
>> specification' of the 1080i30 (normal HDTV) vs. 1080i60 as being
>> normal HDTV. It makes much more sense to use the same units for
>> 720p60 and 1080i30 as meaning that each pixel location is updated
>> at the 60Hz rate in the 720p example, and at the 30Hz rate in the
>> 1080i example.
>
> ATSC does use vertical scan frequency (i.e 60Hz) when describing the format.
> It's not any kind of an official declaration of terminology to the extent it
> could be cited to prove others wrong.
>
>> Frankly, I wouldn't see a need to 'correct' someone who used
>> consistent units, just as I wouldn't see a need to 'correct'
>> someone who used inconsistent units.
>
> Well this the important thing, especially in light of his insistance that
> two fields of interlaced material don't make a frame. Which is clearly
> incorrect.
>
>> As an engineer, I am loathe to mix units, and is why I personally
>> prefer the more consistent 1080i30 (for 30 frames per second) or
>> 720p60 (for 60 frames per second.)
>
> Yes but both 1080i and 720p are 60Hz. So it's a matter of what units you
> are using. Vert scan or frames. Either way it's obvious as to what is
> being refered to just by saying 1080i and 720p.
>
One problem with 1080i or 720p is that 720p might be 720p30 or 720p60.
There are actually some consumer camcorders that use 720p30.

John

 

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"John S. Dyson" <toor@iquest.net> wrote in message
news:c93pfp$2jil$1@news.iquest.net...
> In article <MPG.1b1f13e39eea8545989709@news.gwtc.net>,
> Ron Malvern <rmlvrn@nospam.com> writes:

> > First of all, 1080i is not referred to as 1080i30. It's 1080/60i.
> >
> I have seen it both ways. 1080i30 would be 30 frames per second.
> This would be equivalent to 720p60 as 60 frames per second. Likewise,
> I have also seen it with the inconsistent approach like you suggest,
> where sometimes it is 'frames per second' and sometimes it
> is 'fields per second.' I prefer using the same units all of
> the time, where the number after the i/p is 'frames per second.'

Just because some other people are confused and use the wrong terminology
doesn't mean you should perpetuate their errors...

 

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"John S. Dyson" <toor@iquest.net> wrote in message
news:c98lrd$1021$1@news.iquest.net...

> As an engineer, I am loathe to mix units, and is why I personally
> prefer the more consistent 1080i30 (for 30 frames per second) or
> 720p60 (for 60 frames per second.)

Sorry John, but, regardless of how commonly it may be used, that is an
extremely inconsistent usage and to me quite confusing. To me, that means
that each field is updated 30 times per second, giving an overall framerate
equivalent of only 15fps (and intolerable flickering, unless each field line
is then displayed twice as it would be in a 30p arrangement).

 

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"John S. Dyson" <toor@iquest.net> wrote in message
news:c9ahvd$1k0o$1@news.iquest.net...
>
> One problem with 1080i or 720p is that 720p might be 720p30 or 720p60.
> There are actually some consumer camcorders that use 720p30.

Precisely. And if the last number is used to distinguish between 30p and
60p, why would it suddenly make sense for both 30 and 60 to refer to 60i?

 

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In article <174uc.13918$Fo4.195490@typhoon.sonic.net>,
"Matthew Vaughan" <matt-no-spam-109@NOSPAM.hotmail.com> writes:
> "John S. Dyson" <toor@iquest.net> wrote in message
> news:c9ahvd$1k0o$1@news.iquest.net...
>>
>> One problem with 1080i or 720p is that 720p might be 720p30 or 720p60.
>> There are actually some consumer camcorders that use 720p30.
>
> Precisely. And if the last number is used to distinguish between 30p and
> 60p, why would it suddenly make sense for both 30 and 60 to refer to 60i?
>
For 720p60, that means 60 FRAMES PER SECOND. 1080i30 means 30 FRAMES
PER SECOND. Note the consistency of units.

John

 

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In article <154uc.13917$Fo4.195509@typhoon.sonic.net>,
"Matthew Vaughan" <matt-no-spam-109@NOSPAM.hotmail.com> writes:
> "John S. Dyson" <toor@iquest.net> wrote in message
> news:c98lrd$1021$1@news.iquest.net...
>
>> As an engineer, I am loathe to mix units, and is why I personally
>> prefer the more consistent 1080i30 (for 30 frames per second) or
>> 720p60 (for 60 frames per second.)
>
> Sorry John, but, regardless of how commonly it may be used, that is an
> extremely inconsistent usage and to me quite confusing. To me, that means
> that each field is updated 30 times per second
>
Note that progressive doesn't really have a 'fields per second'
because 'fields per second' is a description of
interlaced scanning. The units in common with progressive and
interlaced scanning is the 'frame per second' description.

SO, when using 720p60, you are saying that 720 scanlines are displayed
every 1/60 of a second. For 1080i30, you are saying that 1080 scanlines
are displayed every 1/30 of a second. However, people also use 1080i60,
but the units are inconsistent with the units used for progressive.

John

 

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In article <TeJtc.28760$zO3.7508@newsread2.news.atl.earthlink.net>,
"FLY135" <fly_135(@ hot not not)notmail.com> says...

> This is simply your re-interpretation of terminology. The fact is that two
> fields of interlaced material has always been considered a frame and that
> usage of terminology is ubiquitous. Just because it violates what you
> consider to be the priniciple that all scans lines must be sampled at the
> same point in time, doesn't mean that calling two fields a frame is wrong.
> While your understanding of what fields are is correct, your use of
> terminology is not.

With the coming of digital television and it's 18 seperate formats
involving muliple frame rates and various means of refresh, including
interlace, segmented frame and progressive, we in the production industry
have had to re-define our terms to be more precisely descriptive. With
the old NTSC system, it was "good enough" to construct a still "frame"
from two fields exposed at different moments, even if the man waving his
hand ended up with eight fingers. In the new world of high definition
production, that sort of thing is clearly no longer "good enough".

 

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In article <%t0uc.3676$Yd3.3467@newsread3.news.atl.earthlink.net>,
"FLY135" <FLY_135(@hot not not)notmail.com> says...
> Well this the important thing, especially in light of his insistance that
> two fields of interlaced material don't make a frame. Which is clearly
> incorrect.

I'm well aware the conventional thinking is that two fields make a
frame. It's taught in all the schools and the convention has been in use
for a long time.
I'm not going to go to war over this because it's not really worth
fighting over. But we've had to change our thinking about fields and
frames with the coming of progressive scan field production gear in the
last few years.
When editing, we have to be careful nowadays about the origin of our
material and how we refer to it in technical specifications and in
editing and special effects instructions; whether a still shot, for
example, is film derived, progressive derived, segmented-frame derived,
or dual-field derived.
In this context, the still derived from two fields is going to be
inferior to a still derived from a film or progressive source because of
the timing mismatch between the fields. In this context, a lot of
editors, including me, have come to the conclusion that a dual-field
still does not qualify as a true frame, and we simply can't use it as
such.

 

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In article <MPG.1b25534d7e3d688b98970e@news.gwtc.net>,
Ron Malvern <rmlvrn@nospam.com> writes:
>
>
>> No, it isn't. I looked in the ATSC spec before I posted (Table A3 of
>> ATSC A53/C summarizes nicely), and the only frame rate information
>> indicates it's 1080/30i. If you want to be thoroughly anal about it,
>> it's probably usually 1080/29.97i (although 1080/30i is allowed).
>> There's no mention of 60i.
>
> Go to the ATSC site and do a search on 30i. Nothing comes up. Do a
> search on 60i and all kinds of references appear. Here's the quote from
> the ATSC's Final Technical Report in which it defines it's terms:
>
Note that the various designations that might be 'common' might
also be somewhat 'odd' or 'nonsensical.' Please refer to 4:2:2 vs.
4:1:1 vs 4:2:0 for example -- but we all know what they mean. Even
worse, 4:2:0 isn't always the same as 4:2:0 in different circumstances.
(The location of the color sample might be different.)

IMO, the biggest problem comes from those who complain against other
people's usage, with GREAT PRECISION and pedantry, but about the usage
that has little precision or formality.

John

John

 

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In article <c9gifa$amr$1@news.iquest.net>, toor@iquest.net says...
> Note that the various designations that might be 'common' might
> also be somewhat 'odd' or 'nonsensical.' Please refer to 4:2:2 vs.
> 4:1:1 vs 4:2:0 for example -- but we all know what they mean. Even
> worse, 4:2:0 isn't always the same as 4:2:0 in different circumstances.
> (The location of the color sample might be different.)
>
> IMO, the biggest problem comes from those who complain against other
> people's usage, with GREAT PRECISION and pedantry, but about the usage
> that has little precision or formality.

I've noticed that the latest publications from SMPTE, the Society of
Motion Picture and Television Engineers, also refers to 1080i as 1080/60i
and the proposed European standard as 1080/50i.