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Old 27th December 2008, 04:05   #1  |  Link
silencer01
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Why We Love 1080p?

Before we decide if 1080p flat panels are worth your hard earned cash, I should probably explain 1080p in the first instance. The best place to start is to familiarise yourself with EICTA (European Information & Communications Technology Industry Association) HD ready specifications. After this you will understand that it is important that a HDTV accepts 1080p source signal as well as being able to display it.

1. Display

The minimum native resolution of the display is 720 physical lines in wide aspect ratio.

2. Video Interfaces

The display device accepts HD input via:

Analogue YPbPr: “HD ready” displays support analogue YPbPr as a HD input format to allow full compatibility with today's HD video sources in the market. Support of the YPbPr signal should be through common industry standard connectors directly on the HD ready display or through an adaptor easily accessible to the consumer; and:

DVI or HDMI: HD capable inputs accept the following HD video formats: 1280x720 @ 50 and 60Hz progressive scan (“720p”), and 1920x1080 @ 50 and 60Hz interlaced (“1080i”); and the DVI or HDMI input supports copy protection (HDCP)


High Definition means having up to 5 times more pixels than Standard Definition. This is calculated by dividing the best HD resolution material (1920 x 1080 = 2073600 pixels) by (720 x 576 = 414720). The immediate result is having more detail and sharpness in your picture. An analogy to this is that if I asked you to recreate a Mona Lisa with paint dots on a canvas, you will be able to do a better job with more dots, on the same canvas size.

Ok back to HD ready specifications. The first requirement is that the HD ready displays must have a minimum horizontal resolution of 720 physical lines in wide aspect ratio (16:9). That means the HDTV should be able to display 1280 x 720 material or 720p format material. There is a small debate regarding the interpretation of wide aspect ratio especially on some plasma TVs. These TVs have native resolution of 1024 x 768. But because the plasma pixels are rectangular, they come in wide aspect ratio of 16:9. The most important thing to realise is that while the screens can accept 720p signals or higher, the signal will have to formatted or downscaled to `fit' the native 1024 x 768 resolution of these TVs, with resulting loss of detail and clarity.

Are you still with me?

I'll use the dots on the canvas analogy again. Imagine that the perfect Mona Lisa picture will be created by a maximum number of dots on a certain canvas size. If the canvas size if reduced, you'll have to throw away some dots, which is a bad thing. Note that the above condition is only a minimum requirement, If I had a choice, I would want to watch 1080 material everyday. There is just so much more detail (so much that Vanessa William is complaining) to see. To do that you will need a display that can show 1920x1080 resolution (16:9 wide aspect ratio).

Right, the next section deals with video interfaces and summarizes the minimum connection specifications that a HDTV must have to be HD Ready. Before we tackle that you should have a basic understanding of interlaced and progressive signals (the i or p behind the number). Interlaced signals arose from a combination of technological limitations in the past. In a Cathode Ray Tube display (earliest mass market TV), the electron gun produced a beam that is scanned across a phosphor screen, lighting it up and producing an image. Now for a PAL signal in UK, the standard definition resolution is 720 x 576. So the beam will need to sweep through 576 horizontal lines (top to bottom, left to right sequentially) to produce a single frame of picture. Early TVs electron beams were unable to do this fast enough in a single frame without causing an uneven picture. So the scanning job was divided in time. First scan the odd number horizontal lines starting with 1, 3, 7, 9, etc then even number lines (2, 4, 6, 8, etc). This resulted in the single frame to split to 2 fields. So with the electrical supply in Europe limited to 50Hz (its 60 Hz in US), the scanning process has been configured to show 50 fields of images in one second. And 50 fields will give you 25 full frames of picture in a second.

As technology improves, progressive scan became the norm. Basically, the scanning is now fast enough to accommodate a single frame without a degradation in picture quality, much like the picture you get at cinemas at 24 frames per second.

Now back to video interfaces. you can see that HD ready specifications call for HD inputs via analogue (component YPbPr) and digital (HDMI or DVI) connections. Pay attention to 720p and 1080i section and the frequency it accepts them at. (50 and 60 Hz) It again makes no mention of 1080p connections or their related frequencies. That is because it is concerned with minimum requirements manufacturer's will have to meet and not consumers expectations. So, the worst case scenario is that you can get a TV with 1080 resolution but cannot accept 1080p signals, and still be HD ready. In some other TVs, you can only get 1080p with HDMI inputs and not through DVI or component inputs.

Below, I'm going to give a few reasons why you should get a 1080p ready HDTV:

1) As above, the Mona Lisa analogy shows that if you want the best quality out there now, you need to get 1080p source material and paint it on a 1080 capable HDTV canvas. That's one-to-one matching. So if you get a TV with 720 canvas, you are going to waste all that extra detail.

I hear people say that there is no difference between a 720 and 1080 picture. Unfortunately, enjoying all that extra detail is also a function of your viewing distance, size of TV and the image resolution (see article). So yes, in some conditions that might be the case. But if you sit close enough, then the 720p picture will cross the pixelation threshold and look poor while the 1080 picture will retain its full glory.

2) 1080p sources are not rare. Home Theatre PCs (at least the powerful ones) are capable of sending 1080p material to your TV. There is some HD material out on the internet, and if I were betting man, in a few years, we will be able to watch HD downloads over the internet via streaming. 1080p BluRay and HD DVD players are on the horizon. Current HD players send out 1080i signals at the present but futures ones will convert them to progressive for output (disc players tend to do this better than TVs). Game consoles will quickly go down the 1080p route as well. Video purists will be able to use the external video processors to improve quality and deliver the final signal to the HDTV in 1080p format.

3) What is 1080p in 24Hz I'm hearing about? Basically, for the ultimate picture quality, 1080p material is decoded directly from the discs (BluRay or HD DVD) at 24 frames per second (the way it was prepared for cinema) and then sent to your HDTV. Here, the TV will multiply the number of frames to either 48 or 72 frames per second to prevent flicker.

4) What about 1080i material, in sports, documentaries etc.? Most video material is shot in 1080 interlaced mode due to bandwidth restrictions. The thing to remember is that 1080i material on a 1080 display will still look better than the 720p material, if the internal TV processing is up to the task.

So where are we again after all this? I am not a big fan of futureproofing as I believe with shorter technology cycles nowadays, you can be wasting your hard-earned money on useless products that are here today, gone tomorrow. But I think that 1080p HDTV is here to stay and that you don't have to pay a premium for this. Just look at how many 1080p TVs are already flooding the market.

In conclusion, when you're thinking of getting a 1080p HDTV, you will want to consider the following points:

1) HD vs SD source. If you watch more HD, a 1080 HDTV is a good investement.

2) Look for 1920x1080 resolution for the HDTV.

3) It has to accept 1080p signal on HDMI and preferably on component YPbPr and VGA interface as well. The latter two are perfectly capable of delivering 1080p data on their bandwidth, albeit without audio.

4) 1080p signal is accepted in 50 and 60 Hz. Movie fans may want the extra feature of receiving 24 Hz input for the TV. This ensures that the TV is futureproof for 1080p/24 HD players for judder-free motion picture.

5) For HTPC fans, the TV must be able to do 1:1 pixel mapping (Dot-by-Dot). This means that every pixel from the source is represented on the screen without any up or down-scaling. This promises the sharpest pictures, especially for LCD TVs.
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