1. Everything you wanted to know about High Definition, or 'HD'!
1.1 - What is High Definition, or ‘HD’?
A. Put simply, High Definition is a TV image which is displayed at a higher resolution than what you used to get (Standard Definition).
The Xbox, Gamecube and Playstation 2 all run in Standard Definition in Australia.
The Xbox 360 will let you start using High Definition capable TV sets to their full potential. You will get a much cleaner image, full of bright, strong colours and crisp lines when running in HD.
You *must* have an HDTV to be able to receive HD content on your TV set.
1.2 - What's the Difference between PAL and NTSC? What is 50htz and 60htz?
A. PAL is the video standard they use in Europe and here in Australia. NTSC is the video standard they use in Japan and America.
Standard PAL runs at a vertical resolution of 576 lines, where NTSC runs at a vertical resolution of 480 lines. If you see 480i or 576i listed anywhere, you know that they are talking about standard PAL and NTSC resolutions.
PAL and NTSC also differ in their 'refresh rates'. PAL will run at 25 frames - 50 fields per second, or a 50htz refresh rate. NTSC will run at 30 frames - 60 fields per second, or a 60htz refresh rate.
PAL and NTSC also differ in the way the reproduce colour, and it is usually considered that PAL has better colour than NTSC.
There is also a video standard known as PAL 60, which runs at the NTSC standard 480 vertical resolution and 60htz refresh rate, but uses the PAL standard colour reproduction.
All these video modes are known as 'SD' or Standard Definition.
1.3 - What are video modes?
A. Video modes are signals which display a video image within the bounds of the rules set by that video mode.
Here is a list of common video modes used to display images on a TV screen:
PAL Countries
SD Video Modes:
576i (PAL) (Screen Resolution 720x576, 50htz)
480i (PAL 60) (Screen Resolution 720x480, 60htz)
ED Video Modes:
576p (Screen Resolution 720x576, 50htz)
HD Video Modes:
720p (Screen Resolution 1280x720, 50htz)
1080i (Screen Resolution 1920x1080, 50htz)
"Full HD"* Video Modes:
1080p (Screen Resolution 1920x1080, 50htz)
NTSC Countries
SD Video Modes:
480i (Screen Resolution 720x480, 60htz)
ED Video Modes:
480p (Screen Resolution 720x480, 60htz)
HD Video Modes:
720p (Screen Resolution 1280x720, 60htz)
1080i (Screen Resolution 1920x1080, 60htz)
"Full HD"* Video Modes:
1080p (Screen Resolution 1920x1080, 60htz)
Note that these video modes aren't bound by their countries of designation; you can buy TVs in PAL countries that support NTSC modes.
* "Full HD" is a term Sony has given to the 1080p video mode, and has stuck through the industry.
1.4 - What do the 'i' and the 'p' mean after 480i, 480p and other video modes?
A. 'i' means 'Interlaced' and 'p' means 'Progressive'.
Interlaced means the image you are seeing is made up of oddly updated lines to create a whole image. In other words, every second line is being flashed up onto the screen during one screen refresh, and every other line is being flashed up on the next screen refresh. This creates a whole image on screen over 2 screen refreshes. It's a little harder on the eyes compared to Progressive.
Progressive means that the whole image (every single line of resolution) is being flashed up onto the screen during each refresh. Remember that PAL has 50 frames per second, or 50 screen refreshes per second, and NTSC has 60.
1.5 - What is 720p, 1080i and 1080p?
A. These are the High Definition or 'HD' video standards. When you hear 'HD', you know that this is what is being talked about.
720p, of course, means that the image being displayed has 720 lines of vertical resolution, and that it is a progressive image. 1080i means there are 1080 lines of resolution, and that the image is interlaced, and 1080p is the same but progressive. 720p runs at a 1280x720 resolution, and 1080i and 1080p run at 1920x1080.
1.6 - What is this ED I keep hearing about?
A. ED (Enhanced Definition) is usually the banner they place the progressive forms of SD resolutions under. So, 480p and 576p is what you would call ED.
They aren't HD resolutions (Unless you're in Australia, more later...), as what is being displayed is still technically the same resolution as it's interlaced SD counterpart, but you are getting a lot more information for a much cleaner image.
1.7 - Wait, I thought 576p *was* HD?
A. Well, actually, you would be right! But that's only here in Australia. The government, when they were deciding what the specs for HDTV would be in Australia, chose the two resolution modes 576p and 1080i. 720p has just been added to the standard as well – ABC uses 720p for their HD channel. Everywhere else in the world considers 576p to be an ED standard.
The jury is out with viewers in Australia whether they themselves consider 576p to be an HD or an ED standard. It's totally up to you. The government however considers it to be HD. So if you're in Australia (of which you are!) and you either think it's HD, or ED, you would be correct.
As far as the Xbox360 is concerned though, 576p isn't HD.
1.8 - What is up converting and down converting (scaling)?
A. Before we get into this, it is important to know that LCD's and Plasma TV sets are fixed pixel displays. This means that any resolution that is above, or below the screens native resolution (the actual amount of dots the screen displays) will be squeezed or stretched to fill the space the screen allows.
eg. You own an LCD TV that has a native resolution of 1366x768. You feed a 720p signal to this display. 720p has a resolution of 1280x720, so of course, that means it fits into a smaller area of your LCD’s screen. What your TV will then do, is stretch the smaller image up to the size of your TV set, so that it fills the entire screen.
This is known as "up converting", or "up scaling", as it is scaling the image up to the screens native resolution to fit it across the entire screen.
You've probably guessed it, but when you feed a signal of 1080i to this same screen, it will of course, have to "down convert" the image to fit on the screen, as 1080i has a resolution of 1920x1080, which means it fits on a screen much bigger than the one you're trying to display it on.
CRT's don't usually have to worry about this, as it can adapt its pixel count depending on the resolution that is fed to it. This means it can display many resolutions as if it were its native resolution. CRT's have their limits though, and currently can't display a resolution up to the level of 720p, and so has to either down convert it to 576p, or up convert it to 1080i. CRT's can do 1080i as there is less information (540 lines) displayed during one refresh, compared to 720 lines that 720p requires.
1.9 – What are screen aspect ratios? What does 16:9 and 4:3 mean?
A. You’ll see many different numbers like these… 4:3, 16:9, 15:9, 16:10… anywhere you go looking for HDTV’s. These little numbers tell you the ‘ratio’ of the screen. Basically the easiest way to look at it is 16:9 = widescreen while 4:3 = standard.
With a bit more detail - it’s basically saying, using 16:9 as an example, that for every 16cms horizontal, there are 9cms vertical when measuring the length and height of the actual screen.
You will see 15:9 or 16:10 quoted around too. These panels cannot be considered real "widescreen" TV's, as they are slightly shorter than full 16:9 and will chop off some of the image when viewing 16:9 widescreen material, or leave some black borders around the image to show the whole picture.
Many movies are shot with a screen ratio of 16:9. This is why you will see black bars at the top and bottom (letterboxing) when watching widescreen DVDs on your standard 4:3 TV.
All Xbox 360 games are designed to run in 16:9, although they can run on a 4:3 TV too - either the game will actually support it properly, or it will run in a letterbox just like 16:9 movies do.
Peace, Love and Games
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