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post #1 of 33 Old 10-21-2007, 03:47 PM - Thread Starter
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I just have knowledge of 120 Hz TVs and a mention that most content is in 60 Hz, but I'm confused on what people mean when they this. With this one TV, the HP-T5884 which I'm considering, apparently it doesn't do 1024 24hz natively, and that it goes back to 60 Hz(native).

What exactly does this mean picture quality wise? Would it have to be a blu-ray for this? Is it something which could make a TV bad and force you to choose another one?
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post #2 of 33 Old 10-21-2007, 03:51 PM
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Quote:
Originally Posted by SephirothXR View Post

I just have knowledge of 120 Hz TVs and a mention that most content is in 60 Hz, but I'm confused on what people mean when they this. With this one TV, the HP-T5884 which I'm considering, apparently it doesn't do 1024 24hz natively, and that it goes back to 60 Hz(native).

What exactly does this mean picture quality wise? Would it have to be a blu-ray for this? Is it something which could make a TV bad and force you to choose another one?

It means 1080p/24 is completely worthless to you if you get the 5884.
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post #3 of 33 Old 10-21-2007, 04:13 PM - Thread Starter
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Originally Posted by D-Nice View Post

It means 1080p/24 is completely worthless to you if you get the 5884.

Still, what exactly is it? If I get the 5084(most likely because I can't find the 58" version in many places), would it be a factor?
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post #4 of 33 Old 10-21-2007, 04:23 PM
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Quote:
Originally Posted by SephirothXR View Post

...it doesn't do 1024 24hz natively, and that it goes back to 60 Hz(native).

What exactly does this mean picture quality wise? Would it have to be a blu-ray for this? Is it something which could make a TV bad and force you to choose another one?

1080p/24 means that you can eliminate the 3:2 pulldown on movie material, which, depending on your equipment, may or may not have noticeable effect.

Technically, you don't really want to watch at 24fps, since you'll get bad flicker, but at some multiple of that (generally 48Hz for movie theaters, or something like 72Hz for a plasma.) Is it a big deal? I dunno, if your equipment does 3:2 well, most probably won't notice the difference, but I am sure some here will disagree
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post #5 of 33 Old 10-21-2007, 04:33 PM - Thread Starter
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Now I must also ask what is 3:2 pulldown. I thought I knew a lot about TVs before I heard terms like interpolate, pulldown, etc.
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post #6 of 33 Old 10-21-2007, 04:37 PM
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Quote:
Originally Posted by SephirothXR View Post

Now I must also ask what is 3:2 pulldown. I thought I knew a lot about TVs before I heard terms like interpolate, pulldown, etc.

see that little button at the top of the page? its called "search"....
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post #7 of 33 Old 10-21-2007, 04:56 PM
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Quote:
Originally Posted by SephirothXR View Post

Now I must also ask what is 3:2 pulldown. I thought I knew a lot about TVs before I heard terms like interpolate, pulldown, etc.

It means one frame is shown three times in sequence, then the next is shown twice, resulting in a 3-2-3-2-3-2 pattern.
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post #8 of 33 Old 10-21-2007, 05:06 PM - Thread Starter
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see that little button at the top of the page? its called "search"....

People seem to discuss it more and how TVs handle it rather than its definition and what it is.
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post #9 of 33 Old 10-21-2007, 05:37 PM
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Quote:
Originally Posted by SephirothXR View Post

Now I must also ask what is 3:2 pulldown. I thought I knew a lot about TVs before I heard terms like interpolate, pulldown, etc.

http://www.dvdfile.com/news/special_...2_pulldown.htm






WHAT THE HECK IS 3:2 PULLDOWN? by Dan Ramer

As we've highlighted hardware technologies at DVDFILE, we've touched upon progressive scan DVD players and line doublers that convert interlaced video to progressive video. (You may have read about the Faroudja line doubler installed in my system when you read my Mr. Blandings piece; Faroudja has the original patent for the reverse 3:2 pulldown process, a general concept I'll soon describe.)Some home theater components that produce progressive scan video have the commendable ability to correct for most of the unavoidable visual distortions caused by the 3:2 pulldown process. Or tech editor was so impressed with the Toshiba progressive scan DVD player he reviewed that it became his reference unit. So let's take a look at the 3:2 pulldown process, discuss why it's necessary, describe the artifacts, and consider how we might get rid of its visual distortions.

Video versus Film

You wouldn't have to read this article if film and video weren't so different. It's due to those differences that the 3:2 pulldown process becomes necessary. So to begin, we should examine the nature of video and film.

NTSC (National Television Standards Committee) Video is composed of 525 horizontal scan lines. In our wonderful world of DVD, 480 of those scan lines are available to contain picture information. NTSC video is interlaced. In other words, even though the video is shown at 29.97 frames (pictures) per second, each video frame contains two video fields. One field is composed of all the odd horizontal scan lines; the other contains all the even horizontal scan lines. So despite the reality that NTSC video displays 29.97 frames or pictures each second, it's actually created as 59.94 fields per second. Consequently, any four sequential video frames (A, B, C, D) are drawn on the video display as A1, A2, B1, B2, C1, C2, D1, D2, where the 1 or 2 represents the field number within the frame. This is what the vast majority of video displays - including, most likely, yours - expects from any video signal source.

Conventional 35 mm and 70 mm film is shot at 24 frames per second. On the motion picture screen, visible flicker is minimized by projecting the film at 48 frames per second. To maintain proper speed onscreen, the projector repeats each frame. So any four film frames would be projected as A, A, B, B, C, C, D, D. Since the frame rates of film and NTSC video are quite different (24 film frames per second as opposed to 29.97 video frames per second), when we transfer film to video or try to display film from video, we have a bit of a problem.

Simply transferring each film frame onto each video frame would result in a film running about 24.9% faster than intended; 29.97 film frames would be shown during each second rather than the correct 24. The clever solution to this problem is to repeat film frames periodically in a very straightforward but mathematically significant way; the resultant redundancy prevents the apparent speedup of the film when shown at the conventional video frame rate. This is how it's done.

Telecine to NTSC Video

The telecine machine used to transfer film to video for composite D2 masters (which may be used for VHS cassettes, laserdiscs, and broadcast) projects film onto a video imager at 59.94 frames per second (identical to and synchronized with the video field rate) and repeats film frames in a recurring 3:2 pattern. In other words, the film frame sequence is A, A, A, B, B, C, C, C, D, D, and so on:

The Telecine 3:2 Pulldown Process for NTSC Video

The first film frame, A, is repeated three times and is recorded as field 1 and field 2 of the first video frame, and field 1 of the second video frame. The second film frame, B, is repeated twice and is recorded as field 2 of the second video frame and field 1 of the third video frame. The third film frame, C, is repeated three times and is recorded as field 2 of the third video frame and fields 1 and 2 of the fourth video frame. The fourth film frame, D, is repeated twice and is recorded as field 1 and field 2 of the fifth video frame. See the pattern?Repeat this sequence six times and 24 frames of film become 30 frames of video.

MPEG-2 and DVD

So the basis of this technique is to restore proper timing by generating redundant image information from four film frames within every five NTSC video frames. But wouldn't it be silly to waste 20% of the storage space on every DVD with duplicate picture data?Fortunately the MPEG-2 standard nicely avoids this inefficiency. When a film source is encoded for presentation on DVD, it is stored at 24 frames per second; each video frame contains all the picture information from each film frame. There is no redundancy or duplication. Such a transfer is written to DVD as 720-pixel wide by 480-pixel high interlaced frames (where each frame contains two 720 by 240 fields), and there are only 24 frames for each second of film. This is known as 480i24. On each DVD encoded from a film source, a flag is inserted within the MPEG-2 data stream that instructs the player to repeat certain fields to reconstruct the 29.97 frame per second interlaced video. The player obliges by performing the 3:2 pulldown in real-time, continually creating interlaced frame sequences just like the one shown in the above figure, "The Telecine 3:2 Pulldown Process for NTSC Video."This capability enables the player to produce video compatible with conventional displays that were designed based on the NTSC video standard.(As we shall see later, progressive scan DVD players take a different approach.)

The Downside

While the 3:2 pulldown process restores the proper speed of the film on video, it generates some unpleasant problems. Two sequential video frames within every five video frame sequence contain images from different film frames. If there is movement of the images on film, 40% of the video frames will contain visually distorted information. Let me steal a figure from my Anamorphic Widescreen piece to demonstrate.


Stationary Camera Camera Panning Left

The video frame on the left is fine. The circle on film was quite still and so the odd and even scan lines paint a stable video picture. Now let's pan left on film, causing an apparent motion of the circle to the right. Notice that within the video frame on the right - one of the two frames in the five video frame sequence that contains fields from two different film frames - the circle is in one position based on the odd scan lines and in another position based on the even scan lines. What a mess. Repeat this process 40% of the time and the eye sees a loss of focus, a smearing of detail, for any moving object. For those frames that contain a quick cut from one scene to another, the image may become even odder:

Scene Change

Here, the film editor has cut from our image of the black circle to images of a green rectangle to the right and part of a blue cone to the left. For a video frame that captures images from these two different film frames, one before and one after the scene change, all three objects appear on the video display for the duration of the video frame. For that brief snatch of time (33.37 msec), our vertical resolution has been cut in half for that film frame.

These are the two spatial artifacts caused by interlacing; I'll touch upon a temporal artifact soon. Now, let's see if we can minimize these spatial flaws as we watch our DVDs.

Line Doublers

Let's start with the solution that's been around the longest, reverse the 3:2 pulldown as the video is converted within a line doubler from interlaced video to progressive video:

Each progressive video frame is reconstructed by weaving together the odd and even fields from images that were derived from the same film frame. The video frames are then shown at double the conventional NTSC video frame rate in a 3:2 repeating pattern. This effectively doubles the number of horizontal scan lines during each second, hence the name of the instrument that performs the work: a line doubler.(It isn't clear whether C2 is derived from interlaced frame 3 or interlaced frame 4; I arbitrarily showed frame 4.)The technically astute might notice that this scheme seems to require going forward in time to reconstruct frame B. Actually, frame buffers and double buffering techniques are used to overcome this problem. This implies that there is a slight delay through such complex video circuitry, but experience has shown that synchronization with non-delayed audio is not an issue.

While lacking strict temporal consistency - every other film image is on the screen for one and a half times longer than the previous film image causing an apparent subtle jerking or juddering during smooth scans - the spatial distortion of interlacing fields from two different film frames is gone. Since the reverse 3:2 pulldown is somewhat complex, requiring some field analysis on the fly to get it right, it's not available in all line doublers. You'll find this feature in the surprisingly inexpensive DVDO line doubler and such high-end video processors as those from Faroudja. Variations on this theme may be found in some quadruplers, interpolators, and scalars, but that's a topic for some other time.

Progressive Scan DVD Players

As I mentioned earlier, film is stored on DVD as 480i at the equivalent of 24 frames per second. When a conventional player recognizes the appropriate MPEG-2 frame repeat flag, it performs the 3:2 pulldown in real-time, but progressive scan players can react to this flag in a different way. Such a player can create progressive video in real-time .It reconstructs each video frame by weaving together its odd and even fields, then repeats the video frames in a recurring 3:2 pattern. The resulting video signal will contain the same frame sequence and the same horizontal and vertical scan rates as are produced by the line doubler. This is a simpler process than is required in a line doubler since the player does not have to examine the fields to determine how to perform the weaving; no DVD derived from film contains a video frame with images from two film frames.

One potential advantage of performing this process within the DVD player is that it's done entirely in the digital domain, so no signal degradation occurs. An external line doubler accepts a DVD's video signal in analog form, such as component or S-video. The line doubler must digitize the video to bring it into its digital processing circuitry. The line-doubled digital video is then transformed to analog once again for compatibility with the video display. With no less than an analog buffer, an anti-aliasing filter, a sample-and-hold, an analog-to-digital converter, a digital-to-analog converter, another anti-aliasing filter, and another analog buffer involved in the conversions from analog to digital to analog, there's quit a bit of circuitry that can get in the way of a pristine signal. Only the most expensive video processors, costing thousands of dollars, will perform these tasks without visibly degrading the video.

Please note that for a video display to properly present such progressive video or line-doubled signal, it must be capable of dealing with about 31,500 scan lines per second - twice the normal rate. Interestingly, the vertical sync rate remains the same as conventional NTSC video, 59.94 Hz.

The Computer and a Possible Future

Because many computer displays are capable of broader ranges of horizontal and vertical scan rates, it is possible to create temporally symmetrical progressive video that runs at two or three times the film's frame rate: 48 or, more commonly, 72 frames per second. To maintain proper timing, each frame must be repeated two or three times, respectively, so the sequence becomes A, A, B, B, C, C, D, D or A, A, A, B, B, B, C, C, C, D, D, D. Each film image is shown on the video display for precisely the same amount of time, creating our temporal symmetry. So not only have we eliminated the spatial distortions, juddering during smooth pans is now gone as well.

48 frames per second require a horizontal scan rate of 25,200 Hz and a vertical sync rate that extends down to 48 Hz. 72 frames per second require a horizontal scan rate of 37,800 Hz and a vertical sync rate that extends up to 72 Hz. Interestingly, many front projectors are capable of these rates. I've received e-mail from home theater enthusiasts who prefer to use their computers as DVD players to take advantage of this flavor of progressive scan on such projectors. I suspect that as more capable video displays become readily available, we may see standalone progressive DVD players that offer the 48 or 72 frame per second playback option.

Parting Thoughts

It's quite remarkable how much the image quality can be improved by eliminating 3:2 pulldown artifacts with an appropriate reverse process while converting to progressive video. Throw in a good anamorphic transfer with no edge enhancement and the presentation is surprisingly film-like. Interested? You can expect progressive scan DVD players to be introduced by several manufacturers this year. Or you might want to investigate a line doubler, perhaps the affordable DVDO. And as HDTV-ready display prices come down, more and more of you will be able to enjoy the best home theater currently has to offer.
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post #10 of 33 Old 10-21-2007, 11:24 PM
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Two questions:

1) From the article: "The first film frame, A, is repeated three times and is recorded as field 1 and field 2 of the first video frame, and field 1 of the second video frame. The second film frame, B, is repeated twice and is recorded as field 2 of the second video frame and field 1 of the third video frame. The third film frame, C, is repeated three times and is recorded as field 2 of the third video frame and fields 1 and 2 of the fourth video frame. The fourth film frame, D, is repeated twice and is recorded as field 1 and field 2 of the fifth video frame. See the pattern?Repeat this sequence six times and 24 frames of film become 30 frames of video."

That doesn't make any sense, because how can one frame hold 720 scan lines of information? The article mentions that NTSC is 480i, then goes on to indirectly say that each frame is 720 scan lines (odd horizontal scan of frame A = 240, even horizontal scan of frame A = 240, odd horizontal scan of frame B = 240)? I know I probably just read this wrong, so can anyone clarify this for me?

2) I don't see how 24fps, 48fps, 72fps, etc. can possibly look any different. For example, if one frame was shown 72 times over 3 seconds (24fps) how would that look any different than showing the same frame only once over those 3 seconds? If the same number of DIFFERENT frames are being displayed per second, then logically the moving picture should look identical.
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post #11 of 33 Old 10-22-2007, 06:04 PM
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Hopefully that large post hasn't scared you off! I'm sure there's nothing wrong with the information in it, but it might be a bit daunting.

Here's 24Hz in as simple terms as I can make it. Movie is shot at 24 frames per second, this means that for every second of the movie, there are 24 images captured.

Televisions, however, typically work at 60Hz in NTSC territories, which means they must show 60 images per second. 24 doesn't fit into 60 evenly, so what is done is the first image is shown three times, the next one twice, the next three times, and so on. Doing it this way fits the 24 frames into 60 nicely, but as every second image is shown for longer, the image "judders" and movement is not smooth.

Newer televisions can now accept 24Hz signals from BluRay or HD DVD players. If they are dealing with the signal properly, it means that it is shown at a multiple of 24, typically that is 48Hz, 72Hz or 120Hz.

The reason most displays don't display the 24fps signal at 24Hz is because the image flickers very badly when you do this. Depending on the display technology, it is sped up to different rates. 48Hz is common with projectors, which means that every image is shown twice - this works well, and is what most cinemas use.

Plasmas typically use 72Hz - this is because 48Hz has a noticeable flicker on a Plasma, due to the way they draw their image.

With LCDs, it shouldn't really matter what they are showing it at, with regards to the image flickering. This is because the rate at which an LCD updates the image onscreen has no effect on flicker. 120Hz is typically used though, as it is supposed to help improve response time.


Some displays out there, usually older ones, may accept a 24Hz signal, but then convert this internally back to 60Hz, which means they re-introduce the judder, completely missing the point of why you are sending it a 24Hz signal in the first place. It sounds like the HP-T5884 is doing that.
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post #12 of 33 Old 10-22-2007, 08:12 PM
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Quote:
Originally Posted by IllusionalFate View Post

Two questions:

1) From the article: "The first film frame, A, is repeated three times and is recorded as field 1 and field 2 of the first video frame, and field 1 of the second video frame. The second film frame, B, is repeated twice and is recorded as field 2 of the second video frame and field 1 of the third video frame. The third film frame, C, is repeated three times and is recorded as field 2 of the third video frame and fields 1 and 2 of the fourth video frame. The fourth film frame, D, is repeated twice and is recorded as field 1 and field 2 of the fifth video frame. See the pattern?Repeat this sequence six times and 24 frames of film become 30 frames of video."

That doesn't make any sense, because how can one frame hold 720 scan lines of information? The article mentions that NTSC is 480i, then goes on to indirectly say that each frame is 720 scan lines (odd horizontal scan of frame A = 240, even horizontal scan of frame A = 240, odd horizontal scan of frame B = 240)? I know I probably just read this wrong, so can anyone clarify this for me?

2) I don't see how 24fps, 48fps, 72fps, etc. can possibly look any different. For example, if one frame was shown 72 times over 3 seconds (24fps) how would that look any different than showing the same frame only once over those 3 seconds? If the same number of DIFFERENT frames are being displayed per second, then logically the moving picture should look identical.

1) yup. you read it wrong. go back and read it again and write it down as you read it. i.e.:

aaa bb aaa bb aaa bb aaa bb aaa bb aaa bb...
becomes
aa ab ba aa bb aa ab....

2) think more about that one. keep in mind that things are happening as time is passing (not static).

- chris

 

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post #13 of 33 Old 11-17-2007, 06:49 AM
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3:2 pulldown makes decent enough sense to me. The question I have is, would any upscaling dvd player (or in my case HTPC) ignore the MPEG-2 frame repeat flag if it notices a proper multiple refresh rate via the hardware and monitor? I suppose there is a similar flag for source bluray/hddvd so the same question applies to that. 2nd, 60hz LCD output should play 29.97hz source without any conversion right? Lastly, how would one know the precise source timing of every single DVD (or xvid, mkv, etc.) created? That is, is it simply assuming everything that came out at the theater is always 24fps, while video (i.e. straight to video in the case of movies and anything other than a movie) is always 29.97hz (if NTSC) and everything on TV mpeg2 hd is 60hz?

I would imagine it's not always that easy and there's a lot of digital releases (i.e. newer star wars) that blur the distinction between film and otherwise no?

TIA
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post #14 of 33 Old 11-18-2007, 09:24 PM
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Originally Posted by D-Nice View Post

It means 1080p/24 is completely worthless to you if you get the 5884.

Gotta love these declarative statements without any meaning - based on this ALL TVs are completely worthless as there's no TV with 24Hz.
In fact even movie theaters are worthless for you because they use 48Hz...


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post #15 of 33 Old 11-18-2007, 09:26 PM
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Quote:
Originally Posted by IllusionalFate View Post

2) I don't see how 24fps, 48fps, 72fps, etc. can possibly look any different. For example, if one frame was shown 72 times over 3 seconds (24fps) how would that look any different than showing the same frame only once over those 3 seconds? If the same number of DIFFERENT frames are being displayed per second, then logically the moving picture should look identical.

It's a lot different for your eyes/brain, think about it...
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post #16 of 33 Old 11-19-2007, 08:19 AM
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The best explanations of these things that I know of are at The Secrets of Home Theater and High Fidelity site. There's a great explanation of deinterlacing and pulldown with good visual aids (animated GIFs) in Part 5 of their October 2000 DVD Player Benchmark (a section about 8 paragraphs down where the background color changes to grey). The same guy wrote a recent article "High Definition 1080p TV: Why You Should Be Concerned" also with good animated visuals.

Enjoy.

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post #17 of 33 Old 11-19-2007, 10:03 AM
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The ideal HDTV does not yet exist IMHO. I have a 1080p LCD monitor I am anxious to replace. It has fixed 60Hz screen refresh as do almost all HDTVs. I see motion judder in motion from film source material, both OTA broadcasts and DVD/HD-DVD, although it is fine with live video feeds like sports.

I also posses an older non-1080p front projector that allows me to select either 60Hz or 72Hz refresh. With that I can have smooth motion with either film source or video source, as long as I switch video modes to match the source material.

What we need IMHO and do not yet have is a quality 1080p display with good contrast and deep blacks (plasma or new technology LED-backlit LCD) that refreshes at 120Hz, accepts 24Hz input from an HD-DVD/Blu-Ray player, accepts 60Hz input from a conventional upscaling DVD player, and rapidly detects 3:2 telecine and switches between film and video modes in OTA broadcasts without a hiccup. Oh, yeah - it needs a really good scaler for 480i and 720p material.

I don't think you can buy such an HDTV now - somebody tell me different, please.

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post #18 of 33 Old 11-19-2007, 10:31 AM
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Originally Posted by Gary McCoy View Post

It has fixed 60Hz screen refresh as do almost all HDTVs

My budget Sceptre Naga x37 will push 24 or 48hz. Have you tried HTPC?
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post #19 of 33 Old 11-19-2007, 12:01 PM
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Quote:
Originally Posted by hakujin View Post

My budget Sceptre Naga x37 will push 24

Now I wanna see THAT, my friend - proof?
I bet your eyes would simply flow out of your skull if it would be refreshing at 24Hz.
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post #20 of 33 Old 11-19-2007, 12:45 PM
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Quote:
Originally Posted by hakujin View Post

My budget Sceptre Naga x37 will push 24 or 48hz. Have you tried HTPC?

Maybe the Sceptre will, I'm not familiar with it. But 120Hz (plus proper processing to go with it) is required to display BOTH film and video source without motion judder.

If you don't notice motion judder today, then quit thinking about it, it'll only end up making you unhappy. I have three HD displays and NONE will let me view SD versions of the old Star Trek series (DS9 and Voyager) off DirecTV without seeing judder. They shot those series on 35mm film, and then telecined the result, THEN added the special effects in video mode. When the display is set for 60Hz, the film scenes with actors display jerky motion. When the spaceships are on screen, they are jerky at 72Hz which smooths out the actors. Nothing short of 120Hz refresh and a fast-switching video processor is gonna fix that.

I do have two HTPCs in the HT and a third in my back bedroom. Dscaler 4 does a fair job on SD-to-HD scaling using my various video boards, but the motion judder is driving me nuts. It's all-too-visible even on the smallest 19-inch display I have.

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post #21 of 33 Old 11-19-2007, 08:38 PM
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Maybe the Sceptre will, I'm not familiar with it. But 120Hz (plus proper processing to go with it) is required to display BOTH film and video source without motion judder.

If you don't notice motion judder today, then quit thinking about it, it'll only end up making you unhappy. I have three HD displays and NONE will let me view SD versions of the old Star Trek series (DS9 and Voyager) off DirecTV without seeing judder. They shot those series on 35mm film, and then telecined the result, THEN added the special effects in video mode. When the display is set for 60Hz, the film scenes with actors display jerky motion. When the spaceships are on screen, they are jerky at 72Hz which smooths out the actors. Nothing short of 120Hz refresh and a fast-switching video processor is gonna fix that.

I do have two HTPCs in the HT and a third in my back bedroom. Dscaler 4 does a fair job on SD-to-HD scaling using my various video boards, but the motion judder is driving me nuts. It's all-too-visible even on the smallest 19-inch display I have.

I don't think I have any material that creates judder that I really care too much about. Maybe some old episodic content from yester-year but poor PQ would more likely supersede this anomaly. Than again, these days I'm primarily watching HD, and DVD.

What are you doing now with dscaler; blending, weaving? Have you tried inverse telecine? I suppose that may not solve the special effects however...

I was not aware that 120hz switches like that or is that your part of your 'wish list'? In any case, that's pretty interesting.

There are some 120hz models available now; BB for one is advertising the crap out of them. Maybe give one a go...
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post #22 of 33 Old 11-19-2007, 09:42 PM
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So how can a layperson know if they are buying a tv that will support 1080p/24fps? And how can a layperson know that the signal coming out of a device like a dvd player is coming out at 1080p/24fps? I understand the theory behind deinterlacing, 3:2 pulldown, etc., but where do the products say something like "this dvd puts out 1080p/24fps," or "this tv needs to process a signal using 3:2 pulldown." And where does this processing happen? In the dvd player or in the tv or in both? Sorry if the answers to these questions seem obvious, but I'm baffled as to how to use this information to make a wise purchasing decision. Thanks.
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post #23 of 33 Old 11-20-2007, 04:00 AM
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I don't think I have any material that creates judder that I really care too much about. Maybe some old episodic content from yester-year but poor PQ would more likely supersede this anomaly. Than again, these days I'm primarily watching HD, and DVD.

What are you doing now with dscaler; blending, weaving? Have you tried inverse telecine? I suppose that may not solve the special effects however...

I was not aware that 120hz switches like that or is that your part of your 'wish list'? In any case, that's pretty interesting.

There are some 120hz models available now; BB for one is advertising the crap out of them. Maybe give one a go...

SO can we see any evidence that your TV supports *any* multiples of 24Hz...?
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post #24 of 33 Old 11-20-2007, 07:42 AM
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Now I wanna see THAT, my friend - proof?
I bet your eyes would simply flow out of your skull if it would be refreshing at 24Hz.

Refresh rates for LCDs are not the same as refresh rates for CRTs. You would not be able to tell the difference between refresh rates of 24, 48, 72, 96, or 120Hz from a 24Hz source with a LCD. That's because there's no flicker with LCD.

What this forum needs is a sticky with what displays accept and properly display 1080p24.

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post #25 of 33 Old 11-20-2007, 08:18 AM
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[quote=xradman;12267862]Refresh rates for LCDs are not the same as refresh rates for CRTs. You would not be able to tell the difference between refresh rates of 24, 48, 72, 96, or 120Hz from a 24Hz source with a LCD.
[quote]

In case you haven't noticed I was joking, my mistake. I know very well both technologies hence my question about his funny claim of Sceptre having lowest vertical refresh rate of 24Hz.

Quote:



That's because there's no flicker with LCD.

Khm, actually there IS a flicker but it's from the backlight and usually insignificant.

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What this forum needs is a sticky with what displays accept and properly display 1080p24.

Properly = without odd pulldown?
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post #26 of 33 Old 11-20-2007, 09:05 AM
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24 Hz (24 frames per second) video signal format transmits the full content of film source and also consumes less bandwidth than 60 Hz or even interlaced 30 frames per second. The latter two have the 3-2 pulldown already there and one of the consequences is a repeated video field or frame for every two film frames, thus representing the difference in bandwidth.

When the TV converts 24 Hz to 60 Hz, the TV is adding the 3-2 pulldown.

Currently the primary use of 120 Hz (so far seen only with LCD) is to reduce motion blur by turning light pixels dark a tad sooner, given the longer time it takes to do light to dark on LCD compared with other display methods.

Only a few 120 Hz TV's match incoming 24 Hz video to the 120 Hz refresh rate (imparting 5-5 pulldown). The simpler processing is to make what appears as 6-4 pulldown. If the incoming video is 60 Hz, the TV has to go through extra effort to dissect the 3-2 pulldown (do inverse telecine) to convert the video to 5-5 pulldown. Without the inverse telecine incoming 60 Hz film source also comes out as 6-4 pulldown.

If the TV accepts incoming 24 Hz, the instructions will say so. If the TV optimizes the display of 24 Hz (using 5-5 pulldown) the instructions will also (explicitly) say so.

Video hints: http://members.aol.com/ajaynejr/v120hz.htm

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post #27 of 33 Old 11-21-2007, 09:10 PM
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In case you haven't noticed I was joking, my mistake. I know very well both technologies hence my question about his funny claim of Sceptre having lowest vertical refresh rate of 24Hz.

Tell me than, pretentious one; what is funny about my 'claim'?

I input custom timing refresh rates into my Nvidia 6800 PC connected via DVI to HDMI to my Sceptre. Each rate refreshs my sceptre and 24hz looks particularly slower as my cursor jumps around which makes it quite unusable for pc usage. 48hz was also tested and added in nvidia control panel and applied with much less difference (though noticeable) than 24hz on the desktop, obviously. 72hz simply won't take in the test mode (which thereby won't allow me to add it to the screen cap 2. Both modes look great when playing back 1280x720p source content (though I tested 24hz very hastily), but so does 60hz.

If my 'not worthy' Sceptre is not outputting 24 and 48hz then what exactly is happening, particularly at 24hz that causes the slowdown. I don't claim to be an expert. :-)




Here's a few grabs of content reporting at 48hz





Now here 60hz that looks better to my eyes than the previous 3, though a large part of that could be due to the source and that I recently changed back to VMR9 Renderer again (vice Haali) and haven't recalibrated appropriately.
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post #28 of 33 Old 11-21-2007, 09:22 PM
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I just have knowledge of 120 Hz TVs and a mention that most content is in 60 Hz, but I'm confused on what people mean when they this. With this one TV, the HP-T5884 which I'm considering, apparently it doesn't do 1024 24hz natively, and that it goes back to 60 Hz(native).

What exactly does this mean picture quality wise? Would it have to be a blu-ray for this? Is it something which could make a TV bad and force you to choose another one?


Read this,

http://www.hometheaterhifi.com/volum...07-part-1.html

Enjoy

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post #29 of 33 Old 11-27-2007, 06:58 AM
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Tell me than, pretentious one; what is funny about my 'claim'?

I input custom timing refresh rates into my Nvidia 6800 PC connected via DVI to HDMI to my Sceptre. Each rate refreshs my sceptre and 24hz looks particularly slower as my cursor jumps around which makes it quite unusable for pc usage. 48hz was also tested and added in nvidia control panel and applied with much less difference (though noticeable) than 24hz on the desktop, obviously. 72hz simply won't take in the test mode (which thereby won't allow me to add it to the screen cap 2. Both modes look great when playing back 1280x720p source content (though I tested 24hz very hastily), but so does 60hz.

If my 'not worthy' Sceptre is not outputting 24 and 48hz then what exactly is happening, particularly at 24hz that causes the slowdown. I don't claim to be an expert. :-)




Here's a few grabs of content reporting at 48hz





Now here 60hz that looks better to my eyes than the previous 3, though a large part of that could be due to the source and that I recently changed back to VMR9 Renderer again (vice Haali) and haven't recalibrated appropriately.

Ummm did it ever occur to you to check the base specs of your panel?
That could decide whether it is doing true 24Hz or something else (e.g. 48Hz)...
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post #30 of 33 Old 12-01-2007, 04:25 AM
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as opposed to my own lying eyes right? or if i can't find it, then my vid card outputting the signal must be wrong?! pffft... you're quite a silly character here. it was easier just to show my settings, but if you have read anything i've said, you would than realize I can do both. however, 24hz is not ideal.48hz is 24hz without the slowdown and the two are not discernible (as far as pq). 48hz is what you'd see if you went to the movie theater anyway.
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