Confusion over 1080i vs 1080p

Newflesh2000 · 2 Dec 2007 at 21:54

Evening all. Currently been reading up on the various HD video formats and I now seem to be suffering from information overload.

Which is the best one to go for when looking at LCD tv's? To me it seems to be 1080i due to it running at higher frame rates so fast moving images look better. However 1080p may have a lower frame rate but it works at higher resolutions so picture quality is improved.

ARRRRRGGGGHHHHHHH!

All I want to do is ensure that whatever LCD tv that I go for will have some modicum of future proving built in.

stuman · 2 Dec 2007 at 21:57

what size screen are you using?

are you dead set on lcd?

1080p is better than 1080i but p is backwards compatable with i.

but there is more to a picture than dots on the screen.

Shimmyhill · 2 Dec 2007 at 22:11

There are no 1080i lcd screens, it will be 720p or 1080p.

I have only seen a 100hz screen in action once but it got added to my marketing rubbish list straight away, a good read up about the tech and it seems it will make some footage worse some slightly better but a defi market tool rather than needed feature.

Newflesh2000 · 2 Dec 2007 at 22:19

stuman said:
what size screen are you using?

Looking at getting a 32in Samsung LCD.

Prefer LCD as i'll probably want to use it with a pc at some point.

So it appears that 1080p will be perfectly fine then. It'll be interesting to see what everyone else thinks.

sid · 2 Dec 2007 at 22:28

There are no 32" 1080p screens

You need 50"+ for 1080p though

sid

Newflesh2000 · 2 Dec 2007 at 22:31

Looks like it will definatly be a 1080i then as i can't afford or have the space for a 50in LCD.

To be honest 1080i looks okay to me when running my xbox 360 through my 24 dell monitor.

Cheers all.

Tesla · 2 Dec 2007 at 22:37

I have never thought 1080i looked better than 720p on a 720p-intended panel.

zealot · 2 Dec 2007 at 22:42

sid said:
There are no 32" 1080p screens

You need 50"+ for 1080p though

sid

sharp make a 32" 1080p lcd

Phil99 · 2 Dec 2007 at 22:55

zealot said:
sharp make a 32" 1080p lcd

Is it a true 1:1 representation of 1080p or just internal processing that can take a 1080p signal and downscale it?

Butters · 2 Dec 2007 at 22:58

Umm, 720p is 1080i. The two are one and the same for all intents and purposes.

divine` · 2 Dec 2007 at 23:04

Butters said:
Umm, 720p is 1080i. The two are one and the same for all intents and purposes.

I was under the impression the 720 and 1080 were to indicated the number of lines of vertical resolution and the p/i for progressive/interlaced...

Is this not the case? If 720p and 1080i are virtually the same then are the same res or what?

Phil99 · 2 Dec 2007 at 23:04

Aside from the completely different resolutions and progressive vs interlaced?

Butters · 2 Dec 2007 at 23:08

There is no difference in resolutions though, thats just it. 1080i is never fully achieved.

1080i shows on the screen two lines apart, they are not shown simultaneously. The first line shows for 1/60th of a second, then the second line shows for 1/60th of a second, therefore the actual framerate is 30 frames per second. Exactly that of 720p.

divine` · 2 Dec 2007 at 23:10

..from my brief reading 720p is 60fps though and 1080i is achieved from the interlacing of two '540' images at the equivalent of 30fps.

1080i not truly achieving that amount of vertical resolution because the lines have to be blurred to prevent twitter or something.

So in what way are they the same?

Butters · 2 Dec 2007 at 23:13

This is taken from a Samsung research paper

To answer the question, it's important to understand the difference between 720p vs 1080i. A 720p signal is made up of 720 horizontal lines. Each frame is displayed in its entirety on-screen for 1/30th of a second. This is know as progressive scan (hence the 'p')The quality is like watching 30 photographic images a second on TV. A 1080i signal comprises 1080 horizontal lines but all the lines are not displayed on-screen simultaneously. Instead, they are interlaced (hence the 'i'), ie every other lines is displayed for 1/60th of a second and then the alternate lines are displayed for 1/60th of a second. So, the frame rate is still 30 frames per second, but each frame is split into two fields, which your brain then puts together subconsciously.

divine` · 2 Dec 2007 at 23:17

...so they're not the same then?

Also, everywhere i'm reading suggests 720p can and often is used at 50/60Hz.

Butters · 2 Dec 2007 at 23:25

divine` said:
...so they're not the same then?

Also, everywhere i'm reading suggests 720p can and often is used at 50/60Hz.

720p is 30FPS, 1080i is 30FPS if anything, 1080i is possibly worse.

You never see the full 1080 pixels at the same time, ergo, 720p is better in that respect.

divine` · 2 Dec 2007 at 23:29

720p assumes a widescreen aspect ratio of 16:9, and a horizontal resolution of 1280 pixels for a total of about 0.92 million pixels. The frame rate (in this case equal to the field rate) can be either implied by the context or specified in hertz after the letter p. "The five 720p frame rates in common use are 24, 25, 30, 50 and 60 Hz (or fps). In general, traditional PAL and SECAM countries (Europe, Australia, Japan, much of Asia, Africa, and parts of South America) are or will be using the 25p and 50p frame or field rates, whereas traditional NTSC countries (North and Central America, South Korea, Philippines) are using 24p (for movies), and 60p for high motion programming. All variants can be transported by both major digital television formats, ATSC and DVB."

zealot · 2 Dec 2007 at 23:29

Phil99 said:
Is it a true 1:1 representation of 1080p or just internal processing that can take a 1080p signal and downscale it?

Sharp LC32X20E and yes its a full 1080p tv can accept 1080p via hdmi or component.

FrankJH · 3 Dec 2007 at 07:58

Even though the sharp is a true 1080p screen - the most common LCD size for this is 40 or 46 inch screens (although larger are available, the cost does rise considerably)

You can get decent Samsung 46" for under a £1k now