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post #1 of 14 Old 01-02-2008, 11:16 PM - Thread Starter
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Hi,
I heard recently that 1080p tv shows are still a ways a way.. and, I've read that a lot of modern 1080p sets can de-interlace 1080i into 1080p.. does that mean that the shows filmed in 1080i will have a 1080p (or near 1080p) image?

This confuses me a little, as on one hand there are arguments saying 1080p sets aren't needed for hi-def tv watchers as nothing is filmed in 1080p, and on the other hand, couldnt you get a 1080p tv show by de-interlacing the 1080i signal?

Sorry if my question is vague or stupid,
Thanks
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post #2 of 14 Old 01-03-2008, 12:35 AM
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There are a number of shows that have been released on HD disc in 1080p24. Many sets will also reverse the telecine process used to bring 24p content to 30i, thus giving 1080p24 with duplicate frames to 60 or 120Hz. This applies to most scripted programming, as well as an increasing number of concerts and documentaries. It is not possible to recover true 1080p60 content from native 30i sources such as sports, but a good deinterlacer will still return a nice image.
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post #3 of 14 Old 01-03-2008, 12:57 AM
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The overwhelming majority of all movies and episodic series shown on TV is a 1080p24 source -- either from a HD camera or telecined from film -- sent in a 1080i carrier.

Some TVs can detect the 1080p24 source within a 1080i carrier. Most cannot. That said, most viewers are unlikely to notice the difference between proper film deinterlace (IVTC) and motion-adaptive video deinterlace on the smaller 40-50" displays which make up the majority of flat panel sales.

You can compare the difference on your TV by setting your Blu-ray player to output 1080i instead of 1080p. That's essentially what the networks are doing with their 1080p24 content.
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post #4 of 14 Old 01-03-2008, 04:26 AM
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Quote:
Originally Posted by Vasant56 View Post

Hi,
I heard recently that 1080p tv shows are still a ways a way.. and, I've read that a lot of modern 1080p sets can de-interlace 1080i into 1080p.. does that mean that the shows filmed in 1080i will have a 1080p (or near 1080p) image?

Sort of depends on how the show is made. Some shows are filmed in native 1080/60i - sports, entertainment, some documentaries and some news shows, and the occasional soap. (Similar shows on ABC, Fox and ESPN are shot in 720/60p)

Other shows - mainly scripted comedy and drama, and some documentaries - are shot 1080/24p (or shot on 24fps film and post produced in 24p), which is broadcast with 3:2 pulldown in 1080/60i (or 720/60p on ABC, Fox or ESPN)

Some TVs can now de-interlace 1080/60i signals that contain a 1080/24p source back to 1080/24p (though most then re-pull down to 1080/60p using 3:2) and thus deliver a reasonably transparent 1080p image from a 1080p source carried over 1080i. (This is because the 1080/24p can be carried losslessly in a 1080/60i signal - vertical filtering not withstanding)

However 1080/60i native video can't be losslessly de-interlaced back to 1080/60p - and this is where the quality of a de-interlacer can really make a difference, as the de-interlacer has to re-create lots of picture information that isn't present in the 1080/60i signal.

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This confuses me a little, as on one hand there are arguments saying 1080p sets aren't needed for hi-def tv watchers as nothing is filmed in 1080p, and on the other hand, couldnt you get a 1080p tv show by de-interlacing the 1080i signal?

1080/60p content isn't yet broadcast or in widespread use for production.

HOWEVER - 1080/24p content is widespread and can be carried losslessly via 1080/60i - though how many TVs de-interlace properly to 1080/24p and then 1080/60p rather than treating 24p material as native 60i is a different question.

Also modern BluRay and HD-DVD releases are in 1080/24p - and many players will output a 1080/60p or 1080/24p signal directly - which is great if you have a 1080p display.
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post #5 of 14 Old 01-03-2008, 07:01 AM
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I thought that nothing is currently broadcast in 1080p and won't be for quite a long time. None of the networks are set up for it. Most broadcasters are still working on setting up 1080i or 720p. Then there would be a matter of bandwidth for cable and satellite do deal with and they're strapped now. Is that correct or am I reading it all wrong?
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post #6 of 14 Old 01-03-2008, 07:17 AM
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Quote:
Originally Posted by joed32 View Post

I thought that nothing is currently broadcast in 1080p and won't be for quite a long time. None of the networks are set up for it. Most broadcasters are still working on setting up 1080i or 720p. Then there would be a matter of bandwidth for cable and satellite do deal with and they're strapped now. Is that correct or am I reading it all wrong?

You are thinking of 1080p60. The bandwidth / technology does not really exist to deliver that today.

Native 1080p24 content -- like that stored on Blu-ray and HD-DVD -- requires less bandwidth than 1080i. Unfortunately, some older STBs and TVs can't handle a 1080p24 signal, so content providers send 1080p24 within a 1080i signal instead. This is the same thing that happens when you set your Blu-ray player to output at 1080i instead of 1080p.
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post #7 of 14 Old 01-03-2008, 08:00 AM
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Quote:
Originally Posted by Vasant56 View Post

Hi,
I heard recently that 1080p tv shows are still a ways a way.. and, I've read that a lot of modern 1080p sets can de-interlace 1080i into 1080p.. does that mean that the shows filmed in 1080i will have a 1080p (or near 1080p) image?

This confuses me a little, as on one hand there are arguments saying 1080p sets aren't needed for hi-def tv watchers as nothing is filmed in 1080p, and on the other hand, couldnt you get a 1080p tv show by de-interlacing the 1080i signal?

Just about every drama-oriented production is captured on 1080/24p master tapes, either directly with 1080/24PsF (segmented-frame) cameras/recorders, or optically telecined from 24p films. U.S. broadcasters deliver digital copies of these 1080/24p recordings through pulldown (inserting extra TV fields/frames) to convert 24 fps into the broadcast rate for 1080i/720p (60 Hz).

Displays or video processors, using inverse-pulldown circuits, can discard these extra fields/frames, which can introduce motion judder in images, then recreate 1080/24p images. 1080/24p master tapes, typically with 270, 440 or more Mbps storage, are further compressed (~17 Mbps maximum video payload for OTA/cable/DBS or 40 Mbps peak for HD discs). This can trim effective resolution (resolvable detail) and filter PQ in other ways. But movie master tape PQ and final home delivery, because of 'artistic' camera filtering and other factors , has quite limited effective resolution to start with (~800--1100 lines) compared with a potential 4000-plus lines (equivalent) on film negatives. (This pdf paper details why film on theater screens approximates 1280X720p HD resolution.)

Hardware to view 1080/24p varies widely, with a growing number of displays, after inverse pulldown, able to repeat extracted 24 fps at even multiples, avoiding judder, instead of at 60 fps, the same rate typically used after deinterlacing 1080/60i (30i) or displaying 720/60p. HD disc players may deliver movies at 1080/60i, 1080p60 (@74 MHz sampling, not @148 Mhz), or 1080/24p for U.S. viewing.

1080p displays with measured 1920X1080 resolution from test patterns--not all are capable --could resolve gradual enhancements to HD effective resolution. But a startling number of displays employ a basic, inadequate, type of deinterlacing that can halve vertical resolution (see Gary Merson's three sublinked articles ).

Live or recorded 1080i, already typically appearing crisper than 720p with half the format/spatial resolution, has more headroom for resolution gains. Estimates vary, but ~1450 lines maximum effective horizontal resolution today could theoretically be boosted closer to full 1920X1080 by oversampling, say with ~4k cinema-type digital cameras, or 4k telecines of film negatives/prints, then downconversion to 1920X1080. (Some HD discs are produced this way, although updated measurements similar to sspears' several years ago haven't been published/posted AFAIK.) Standard ~74-MHz 1080 sampling today has a limiting resolution (see effective resolution link) of ~1700 lines. Oversampling/downconversion can boost this limiting resolution. -- John
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post #8 of 14 Old 01-03-2008, 09:36 AM
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Quote:
Originally Posted by joed32 View Post

I thought that nothing is currently broadcast in 1080p and won't be for quite a long time.

That is correct - no network currently broadcasts a 1080p native signal.

HOWEVER - that doesn't mean that 1080p isn't in use for production - it is and has been for many years in the case of 1080/24p, 1080/25p and 1080/30p. Most modern 1080 line production gear - high-end cameras, switchers, servers, VTRs etc. can cope with both 1080/24-30p as well as 1080/50i and 1080/60i, as they are all roughly the same bandwith, and can be carried losslessly in 1080/48i to 1080/60i signals (1080/48i is effectively how 1080/24psf works - of course with no motion between fields)

The way broadcast networks operate it is not feasible to switch between 1080/60i or 50i and 1080/24-30p transmission modes dynamically - so a fixed format of 1080/50i or 60i is used.

1080/24p-30p can be broadcast losslessly within 1080/60i and 1080/50i signals (using a combination of 2:2, 3:2, speed-up and slow-down) though - allowing a decent de-interlacer to reconstruct the 1080/24-30p signal.

HOWEVER - 1080/50p and 1080/60p are different - and still not in widespread use for production, and no current broadcast system deployed in the consumer realm in the US, Japan, Australia, Europe etc. can deliver them to the consumer.

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None of the networks are set up for it. Most broadcasters are still working on setting up 1080i or 720p. Then there would be a matter of bandwidth for cable and satellite do deal with and they're strapped now. Is that correct or am I reading it all wrong?

For 1080/50p and 1080/60p - and for 1080p native broadcast at any frame rate you are correct.

HOWEVER - 1080/24p and 1080/25p are in widespread use (1080/30p less so) for worldwide HD production - and can be broadcast losslessly by broadcasters using 1080/60i or 50i - though it requires a decent de-interlacer to do so.
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post #9 of 14 Old 01-08-2008, 12:23 PM
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Can you tell me the advantage to trading off my 65" Mits 1080I for a new 61" 1080P DLP unit?
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post #10 of 14 Old 01-08-2008, 12:50 PM
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Originally Posted by moez View Post

Can you tell me the advantage to trading off my 65" Mits 1080I for a new 61" 1080P DLP unit?

Very little, unless it can directly support 24fps without 3:2 pulldown - and only if you have an HD optical disc player. Otherwise, you gain nothing - except for a smaller screen.

The only other consideration would be a greater number of HDMI inputs or other features.
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post #11 of 14 Old 01-08-2008, 12:55 PM
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Originally Posted by moez View Post

Can you tell me the advantage to trading off my 65" Mits 1080I for a new 61" 1080P DLP unit?

Welcome to the forums. Just finished outlining some pro/cons relating to someone thinking of scrapping his on-the-blink Marantz 1080i CRT RPTV. -- John
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post #12 of 14 Old 01-08-2008, 01:21 PM
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Originally Posted by sneals2000 View Post

Sort of depends on how the show is made. Some shows are filmed in native 1080/60i - sports, entertainment, some documentaries and some news shows, and the occasional soap. (Similar shows on ABC, Fox and ESPN are shot in 720/60p)

Other shows - mainly scripted comedy and drama, and some documentaries - are shot 1080/24p (or shot on 24fps film and post produced in 24p), which is broadcast with 3:2 pulldown in 1080/60i (or 720/60p on ABC, Fox or ESPN)

Some TVs can now de-interlace 1080/60i signals that contain a 1080/24p source back to 1080/24p (though most then re-pull down to 1080/60p using 3:2) and thus deliver a reasonably transparent 1080p image from a 1080p source carried over 1080i. (This is because the 1080/24p can be carried losslessly in a 1080/60i signal - vertical filtering not withstanding)

However 1080/60i native video can't be losslessly de-interlaced back to 1080/60p - and this is where the quality of a de-interlacer can really make a difference, as the de-interlacer has to re-create lots of picture information that isn't present in the 1080/60i signal.



1080/60p content isn't yet broadcast or in widespread use for production.

HOWEVER - 1080/24p content is widespread and can be carried losslessly via 1080/60i - though how many TVs de-interlace properly to 1080/24p and then 1080/60p rather than treating 24p material as native 60i is a different question.

Also modern BluRay and HD-DVD releases are in 1080/24p - and many players will output a 1080/60p or 1080/24p signal directly - which is great if you have a 1080p display.

By "Vertical filtering" do you mean filtering out "Twitter" from the interlaced image? I was thinking that if 1080p24/30 COULD be losslesly carried on a 1080i60 signal then the filtering must happen when the content is captured (a native 1080i60 signal).
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post #13 of 14 Old 01-08-2008, 04:14 PM
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Originally Posted by Dom2u View Post

By "Vertical filtering" do you mean filtering out "Twitter" from the interlaced image? I was thinking that if 1080p24/30 COULD be losslesly carried on a 1080i60 signal then the filtering must happen when the content is captured (a native 1080i60 signal).

24p and 30p content can twitter just as much as 60i, and can be filtered much later than capture to remove it. (It is true that in 60i output CCD cameras this filtering is effectively done by the line-offset line-pair averaging that creates an interlaced signal from a frame sensor at capture)

Whether post production paths for 24p and 30p productions actually do include a vertical filtering to remove interline twitter, for native interlaced displays, I don't know - I've heard that they don't usually these days.
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post #14 of 14 Old 01-09-2008, 07:33 AM
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Thanks guys for all of the insight.
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