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Old 03-30-2008   #7
rex
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Default No difference between 1080i and 1080p!

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Originally Posted by Ken S View Post
Why, what's the point?
I am just speculating about a possible answer to your original question. BTW, how do you know the discs are mastered at 1080i instead of 1080p? If the original music videos were shot in 1080i video then there would be no benefit to a 1080p recording. The Planet Earth, on the other hand, was shot using in the same 1080p/VC-1 encode that Blu-ray uses, so you get the full benefit of the format.
As you know, most hollywood movies are still shot on film (or HD video) at 24 fps. Few people realize that for these movies there is no difference between 1080i and 1080p. 1080p output contains no additional information, but merely repeats some of the same information (3:2 pulldown). The result is the same whether this deinterlacing is done by the player or your TV. See: http://www.digitalvideofestival.com/...&id=1182107778

There Is No Difference Between 1080p and 1080i
My bold-printed, big-lettered breaker above is a little sensationalistic, but, as far as movies are concerned, this is basically true. Here's why. Movies (and most TV shows) are shot at 24 frames per second (either on film or on 24-frame-per-second HD cameras). Every TV sold in the United States has a refresh rate of 60 hertz. This means that the screen refreshes 60 times per second. In order to display 24-frame-per-second content on a display that essentially shows 60 frames per second, you need to make up or create new frames. This is accomplished by a method called 3:2 pulldown (or, more accurately, 2:3 pulldown). It doubles the first frame of film, triples the second frame, doubles the third frame, and so on, creating a 2-3-2-3-2-3 sequence. (Check out Figure 1 for a more colorful depiction.) So, the new frames don't have new information; they are just duplicates of the original film frames. This process converts 24-frame-per-second film to be displayed on a 60-Hz display.

It's Deinterlacing, Not Scaling
HD DVD and Blu-ray content is 1080p/24. If your player outputs a 60-Hz signal (that is, one that your TV can display), the player is adding (creating) the 3:2 sequence. So, whether you output 1080i or 1080p, it is still inherently the same information. The only difference is in whether the player interlaces it and your TV deinterlaces it, or if the player just sends out the 1080p signal directly. If the TV correctly deinterlaces 1080i, then there should be no visible difference between deinterlaced 1080i and direct 1080p (even with that extra step). There is no new information�nor is there more resolution, as some people think. This is because, as you can see in Figure 1, there is no new information with the progressive signal. It's all based on the same original 24 frames per second.

Last edited by rex; 03-30-2008 at 07:17 PM..
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Old 03-30-2008   #8
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Default Re: No difference between 1080i and 1080p!

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I
There Is No Difference Between 1080p and 1080i
My bold-printed, big-lettered breaker above is a little sensationalistic, but, as far as movies are concerned, this is basically true. Here's why. Movies (and most TV shows) are shot at 24 frames per second (either on film or on 24-frame-per-second HD cameras). Every TV sold in the United States has a refresh rate of 60 hertz.
Rex,

Most good TV's and projectors CAN and DO display 1080p/24, and I must almost totally disagree with you on this post. Don't take it personally, but ask Jerry, Andrew, (I already stated my opinion) and they will all agree with me...
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Old 03-30-2008   #9
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Default Re: Blu-ray Resolution

Kenny,
Don't worry I won't take any corrections you make personally. If I post something erroneous I would like to know about it. But what exactly do you disagree with?
I agree that if you have your BD player set to 1080p/24 output and if your display is capable of displaying 1080p/24 at a refresh rate of an even multiple of 24 (actually 23.97) such as 24, 48, 72, or 120 then you can have that "true cinematic 24fps experience" (like some Pioneer plasmas' 72 Hz or some Sony and JVC projectors' 96 Hz).

Although there are now many 120 Hz LCD displays coming out. None are capable of 5:5 pull down (24x5) which is truely unfortunate, since 120 is the magic number evenly divisible by both 24 and 60. (If I am wrong about this, someone please post.) The overwhelming majority of displays currently in use are not capable of this. In fact, even some of the most recent displays which market themselves as "1080p/24 compatible" are merely capable of receiving 1080p/24 input which is then deinterlaced to display at 60Hz.

Since most current HDTVs cannot display 1080p/24, when you connect your BD player to an HDTV that does not have 1080p/24 input and display capability but only has 1080p/60/30 or 1080i input capability, the player automatically sends its 1080p/24 signal from the disc to its own video processor which then outputs a 1080i/60 signal. This leaves the HDTV to do the final step of deinterlacing and displaying the incoming 1080i signal in 1080p, which is why the article I quoted stated (facetiously) that there is no difference between 1080i and 1080p.
(As the article I quoted mentioned, the Samsung BD-P1000 does something a bit more complicated. This Blu-ray player reads the 1080p/24 signal off the disc, then it actually reinterlaces the signal to 1080i, and then deinterlaces its own internally made 1080i signal in order to create a 1080p/60 signal for output to a 1080p input capable television. However, if it detects that the HDTV cannot input a 1080p signal, the Samsung BD-P1000 just takes its own internally created 1080i signal and passes that signal through to the HDTV, letting the HDTV do the final deinterlacing step.)
Again, if I stated anything incorrect, Andrew, Jerry, or anyone else please chime in, and explain. I will gladly stand corrected.
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Old 04-01-2008   #10
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Default Re: Blu-ray Resolution

In standard broadcast television, with interlaced video, there are two fields that make up each frame - each of these fields contain HALF the image. If first field contains all odd scan lines, then the second field contains all the even lines. The FIELD rate is 60 per second, but the FRAME rate is half that or 30 per second.

To convert interlaced video to progressive video, the two field portions are combined so that the screen is painted in a single pass. I suspect this is done by buffering the field information until enough of the data is in to begin painting the screen, timed such that last data will be available before the last of the image is to be painted, and paint it again with the same data while the new frame data come in, so that flicker is not observed. Processing could be performed on the second pass though, based upon a "history" of the data from preceding passes to either accelerate the next screen draw, or to improve its quality in some manner. If the source was truly progressive, then it could potentially contain new data on each pass.

The "pulldown" mechanism for movies works pretty much as you described for legacy content. I am unsure about what happens for new all-digital content though, since it may have no legacy compatibility requirements.
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Old 04-06-2008   #11
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Default Re: Blu-ray Resolution

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Although there are now many 120 Hz LCD displays coming out. None are capable of 5:5 pull down (24x5) which is truely unfortunate, since 120 is the magic number evenly divisible by both 24 and 60. (If I am wrong about this, someone please post.)
Since my earlier post, I have been informed that the Sony XBR4/5 series LCD's do in fact do a 5:5 pulldown. Most other 120Hz displays do the usual 3:2 pulldown (as described above) then double to get 120Hz. Unfortunately, these Sonys convert everything, even TV video encoded at 60Hz to 24p, which can introduce artifacts, etc. Sony has traded one problem for another; but they made a good choice, since by far most media are encoded in 24p. Hopefully, there will soon be displays capable of 5:5 pulldown for 24p sources and also 2:2 or 4:4 pulldown for video sources, like TV programming, etc.
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Old 04-07-2008   #12
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Default Re: No difference between 1080i and 1080p!

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Rex,

Most good TV's and projectors CAN and DO display 1080p/24, and I must almost totally disagree with you on this post. Don't take it personally, but ask Jerry, Andrew, (I already stated my opinion) and they will all agree with me...
Kenny,
If you are going to state publicly that you disagree with a post, the least you could do is explain why you disagree.
What exactly do you disagree with? If I have stated, or repeated anything incorrect, I would certainly like to know what it is. If not, that would also be good to know.
No displays actually display at 24 Hz, which would be unwatchable due to the flicker. The fact that some (very few) display at an even multiple of 24 (e.g. Pioneer Plasma's 72 Hz), does not, in any way, make anything stated in my post incorrect. In fact, the original article goes on to say that the 3:3 pull down, used by Pioneer (though slightly smoother than 3:2 pull down) goes through essentially the same process. So what exactly do you disagree with, and why? Thank you for your reply.
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