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I also wonder at times if people have seen high quality 60i broadcasts on a high quality 1080p plasma. On my 1080p 60" Pioneer Elite Kuro, motion is beautiful and interlaced artifacts are minimum and most times simply absent. This is a far cry from the interlaced artifacts we used to get under our old NTSC system. In fact, I much prefer 60i and its higher resolution to 720p broadcasts. Yes, I'll take 60p over all of them, but we're a long way from there. |
Kevin, yes, the de-interlacing of the progressive displays is "good enough" - no doubt, it's probably as good as it could ever get if you buy the best video processing tech today. BUT, it will never be "perfect", as in shooting progressively for display on progressive televisions. Now, you're talking native language to the display - no complicated conversions required, which result in nominal to significant reductions in original resolution.
It's like buying an E85 vehicle or whatever they're called and instead of using that fuel, installing some sort of converter to allow you to keep filling up with reg. gasoline which screws up your fuel economy. It doesn't make any sense, LOL! |
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I am in the fortunate position to own both an interlaced HDTV and a couple progressive HDTV's (PDP & LCD). If I watch SD DVD's (480i material) on the progressive sets, I can spot interlaced artifacts - easy to see the jaggies on the edges of circular objects as the camera is panning across them. If I watch that same DVD on the Sony interlaced CRT, presto, jaggies are gone! Sure, the image is "softer" but I'd rather have that than distracting artifacts. |
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I don't yet have an LCD or plasma TV (I am in the market for one), but the above fact makes me wonder why a lot of people say that 30P video looks bad. It must indeed look bad, or people wouldn't say that; but the only thing I can think of is that possibly a lot of TVs somehow don't handle a true 30P signal proplerly and that causes display problems, because other than some sort of problem like that, 30P and delinterlaced 60i should look quite similar. Historically, interlace was introduced mainly to solve the trade-off between flicker and phosphor persistence in CRT tubes. Phosphors can be made short or long persistence. Long persistence phosphors don't flicker at low refresh rates, but they tend to smear motion. OTOH, a phosphor with a persistence short enough to display 30 fps without smearing would have too much flicker in bright ambient light. So, the compromise trade-off was to interlace the video to increase the effective display rate to 60 Hz, eliminating flickering without taking any extra bandwidth than 30 fps. Now that displays store frames and fields in RAM, this persistence issue goes away, even for plasma TVs (which still use phosphors, but in a different manner than CRTs). |
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As far as fixed pixel devices such as plasmas, I think you may be living a bit in the past. Most of the modern plasmas of today have virtually perfect deinterlacing. This is a very easy accomplishment for any decent plasma of today. Take a look at Gary Merson's tests on this and you'll see the vast majority of HDTVs he tested did perfectly in this regard. My Pioneer presents virtually no interlaced artifacts with 60i. So for me this is simply a non-issue. This is why I prefer the significantly higher resolution of 1920X1080i broadasts to 720p broadcasts. But again, each to his own. Oh, and one last thought. Not many people are aware that over 90% of scenes on TV are static or nearly static in nature (including sports!). So even the issue of fast movement as a plus for 720p is somewhat exaggerated. |
We may be missing each other with semantics. I'll give you a specific example. I dropped by my parents' house with one of my kids last year. They have a really nice Sony XBR(3?) 52" LCD that was playing Cars to help keep my kid in check while we visited. We also have the DVD so I started to watch a bit more closely. One of the scenes in the middle of the movie begins with McQueen in court. During the opening of that scene, the picture pans across the statue in front of the courthouse. At one point in that pan, you can see quite a bit of artifacting present in the grill of that statue, which I showed my dad. It's when the local law enforcement says, "The Radiator Springs court is now in session" or something along those lines. I remember the audio better because we went back and forth comparing the de-interlacing capabilities of the display vs. the upconverting DVD player and the dialog got embedded into my brain, LOL!
Inside the courtroom, the picture at one point pans across the VW van. The circular emblem of the VW displayed severe jaggies during that pan (as one would expect). I apologized to my dad for potentially ruining his future viewing experience by showing him what to look for in interlaced video playing on progressive televisions, and of course began to explain that one of the primary attractions of HDM (format war was undecided at the time) was to finally be able to get away from authoring interlaced discs. When I got home, I played the same scenes on my PDP. My 50" plasma did not exhibit as severe artifacts probably because it is only a "720P" rez display, but they were there nonetheless. I then played the same scenes on my 34XBR970 interlaced HDTV CRT. Perfection. Although the TV could not physically compete with the raw rez of the 1080P LCD, the picture was much more pleasing and completely artifact-free. http://www.hqv.com/technology/index1...TOKEN=50840332 I consider the above required reading on the subject of de-interlacing in today's world of consumer electronics. It also shows the degree of variability among video processing technology currently used in both display and playback devices. As I've said before, anyone who is interested can pick up one of their de-interlacing torture test discs and see how their playback chain holds up. |
Aaron, I know exactly what you're talking about. But you are missing the fact that there were all kinds of nasty artifacts with our NTSC system, many of them interlaced artifacts. There were many test scenes on calibration discs once DVDs came out that vividly pointed these interlaced artifacts out. This really is a very well known issue with NTSC.
As far as what you see, it's virtually absent with a combination of a good DVD player and plasma. I've got a Panasonic BD30 Blu Ray player and together with my Pioneer plasma, I simply don't see this kind of issue. As I said, Gary Merson did an excellent write up on this and most of the better plasma displays of today do a perfectly good job of deinterlacing. LCDs exhibit many of their own weird artifacts including motion artifacts, which is why I'd never use an LCD as my primary viewing display. For me nothing beats the reality and overall pictrue quality of a good plasma to say nothing of a far better, much more immersive home theater experience than a small CRT. Most reviewers of the new Pioneer Kuro plasmas have called them the best TVs ever and I don't think they'd get that reputation if they displayed lots of interlaced artifacts. |
I can relate to this discussion too. Until last fall I had a Sony HiScan 1080i CRT that I got almost solely to watch the output from my FX1 since the results for normal cable TV were not that good compared to the lower resolution JVC iArt TV we have in the family room. Just before Christmas I decided to treat myself to a new 40" 16x9 and at first got a Samsung LN-T4069 one of the new 120hz 1080P LCD's. I immediately disliked it the moment I got it home!!! I subsequently changed it for a Panasonic 42" 1080P Plasma which I like much better though to be honest for normal SD programming from cable the iArt CRT is far superior. My grandson's Cars DVD plays fine on both the iART and from the PS3 to my Panasonic over HDMI. What I find interesting is that my own HDV, DV or AVCHD seem to play much smoother and with apparent higher resolution for the AVCHD and HDV on the Panasonic than even the few BluRay discs that I have, they are concert videos so likely not from 24p film? Certainly the AVCHD video is like looking through a window viewing outdoor shots of my grandson.
Upconversion from the PS3 is also of interest. Some SD discs like the first Norah Jones are wonderful but others are just awful!!! The combination of scaling/de-interlacing in all the playback and display chain can lead to a lot of problems that I do not think were as evident in a consistent interlace world. The combination of using 24p video shot badly, compressed for transmission over cable as interlace and then displayed on a low cost LCD can be almost unwatchable!!!! Ron Evans |
Ron, you bring up a couple of good points. All DVDs are not created equal. I can remember a few years back when people were talking about 'banding' with fixed pixel displays. True, many displays did have banding issues, but what many people missed was that often the DVD was the culprit!
I'd put the 'offending' DVD on my 34 Panasonic CRT HDTV and saw the same banding I saw on my Fujitsu plasma of that time! But a well mastered DVD (which are more common today than a few years ago), on a good plasma, should show not show any more noticeable artifacts than a CRT. I really don't want to get in to the CRT vs plasma argument, but having had a few CRT HDTVs (including a Zenith 64" RP HDTV with 9" guns and the 34" directview Panasonic), I find the better plasmas produce far superior picture quality. Issues such as misconvergence, focus, linearity, purity and many others are totally missing in plasmas. That together with the far greater, more immersive size of many plasmas makes this a 'no-brainer'....at least for me. ;) |
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Actually much of the problem with 24p video on DVD rests with the DVD player and not the HDTV.
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Aaron the interesting part is that within the BluRay of Shakira concert in Miami the long shots are really nice and actually look higher resolution than the close shots from the cameras in front of the stage which also have judder in the backround. IT seems that some cameras have judder and some don't as if the cameras were shooting at different frame rates!!! Interestingly the BluRay of Queen in Montreal, which was shot on film, in some respects has less judder than the Shakira disc. I don't know if this is due to the camera persons for Queen being used to film technique and thus manage the judder better than the modern camera persons using 30P for the Shakira concert!!!! Suffice it to say the Nora Jones SD video is better than either of these BluRay discs as far as motion judder is concerned. All discs played from my PS3 with latest firmware viewed on my Panasonic 42" 1080p Plasma.
THe first Nora Jones DVD is much better than the second by the way. Ron Evans |
Interlaced video
There is some conflicting info in this thread about how fixed pixel displays handle interlaced video. A few users said that 60i is deinterlaced to 30p. Others say that video recorded in 60i gives smoother motion than 30p. Both of these assertions can not both be true.
I have not been able to find any definitive references on the subject, but let's look at it logically. Assume that we have a native 60i video source and a modern fixed pixel display. If the 60i input stream was simply deinterlaced to 30p, then half of the motion resolution of the original 60i source would be lost! A better approach would be to use intelligent processing (deinterlacing, interpolation, etc.) to generate 60p, thereby retaining the full motion resolution. This would explain why some people perceive 60i to give smoother motion than 30p, and also why the camera manufacturers continue to use 1080/60i as their primary recording mode. If 60i was reduced to 30p on playback, there would be no reason to record in 60i. Therefore it seems logical to conclude that modern fixed pixel displays process 60i input to produce 60p display, and 60i video does in fact give better motion handling than 30p. If anyone can prove me wrong, please do. :) |
I think that you may be correct Bob. I can playback from two players onto my Panasonic 1080p plasma. From an older combined DVD/VHS Sony player and from a PS3. The PS3 is connected by HDMI and will upscale to 1080p playing back DVD's. There is noticeably poorer motion from the PS3 over HDMI than from the older Sony DVD over component. OF interest is that playback over HDMI from my SR11 is smooth!!! So the PS3 conversion is not doing as good a job as the Panasonic.
Ron Evans |
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The entire attraction of 24p and 30p in video totally eludes me. The video should not call the viewer's attention to the flaws, but rather the subject material. |
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http://en.wikipedia.org/wiki/1080i http://hometheater.about.com/od/tele...80ivs1080p.htm These pages, and others, imply that 1080i is always deinterlaced when displayed on a progressive display. If it wasn't, jaggies would be visible since on a progressive display all 1080 lines are refreshed progressively. It's hard to tell for sure, but what I read from these and other pages is that after deinterlacing, many TVs then just display the same deinterlaced frame twice in a row, resulting in a screen refresh of 60Hz, but effectively still just 30 fps in terms of the video motion. Ostensibly, this is called 2:2 pulldown. I assume it is possible, however, that some TVs do more complex processing, such as interpolating frames to try to get closer to true 60Hz (or even 120Hz) motion. Such interpolation would be fairly complex, however, as it would have to involve motion detection in order to get a good quality interpolated frame (just doing static interpolation would not look very good). Some expensive TV's may do this, but I doubt all TVs do, especially cheaper ones probably just use 2:2 pulldown. If somebody knows of a definitive source of information on which TVs, if any, do motion interpolation, that would be really nice. |
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I have not come across ANY progressive television that is capable of doing this. I have not come across ANY AVR that will do this either. And there have only been one or two BD players EVER MADE that can do this. So everyone who complains about 30P has never seen it processed on the same level playing field (i.e., correctly processed) as 60i. The only way you can say that 60i yields better motion handling than 30P is if your display chain properly de-interlaces 60i while it does not properly de-interlace 30P. I'm going to edit this because the marketplace has changed since I last reviewed this issue. http://www.hqv.com/products.cfm This is a decent link that shows some of the products that are using the Reon chipset that has been credited with properly de-interlacing 30P video in the past. I suppose the implementation of that technology could still be questioned however. Also, ABT is set to release an HD version of their venerable SD de-interlacing chipset (the one used in that stellar Oppo SD DVD player) that is slated to be even better than the Reon. We shall see in a few months I suppose. I also fired off an email to HQV asking for some clarification. If I get a response, I'll add it here... |
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Assuming you have software that lets you force the deinterlace method to weave (or has smarter deinterlacing), perhaps one workaround would be to use a PC for displaying 30F video to the TV, essentially just using the TV as a 60Hz monitor and letting the PC do the deinterlacing. |
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In terms of frame rate for smooth motion 60i is closer to 60p. The camera is taking 60 pictures a second but only sending out odd or even scan lines for each of these pictures. In an interlaced world the CRT phosphors and our brains filled in the detail to emulate 60 frames a second. For me the frame rate is more important. I want smooth motion. Modern electronics should be able to emulate this interlace effect through interpolation and display a true progressive, smooth image. 24p and 30p cannot generate this smoothness there just aren't enough frames.
Ron Evans |
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As I mentioned earlier in this thread, I find it interesting that ATSC includes 1080/30P as a valid broadcast format. Now that I think about it again, though, I don't think any of the progressive displays in use today would have any problems at all correctly displaying 1080/30P as 1080/60P (by frame doubling) because it would be a progressive broadcast signal not requiring any de-interlacing. The set would simply receive a full frame and then flash it twice to hit its 60Hz refresh rate. |
Ron, that's not how interlaced fields are de-interlaced by progressive sets. The set buffers field A while waiting for field B comprising frame 1. The video processor then combines fields A+B and processes the resultant frame 1 and tries to mitigate the damage through various de-interlacing algorithms. This yields 30fps, NOT 60fps. The video processor then flashes frame 1 twice to hit 60Hz refresh rate of today's progressive sets. No where does the video processing chipset attempt to interpolate the even scan lines missing from field A, nor the odd scan lines missing from field B. It combines these two fields and may interpolate or apply motion adaptive technology in order to eradicate the inherent interlaced artifacts present from interlaced capture during acquisition.
Assuming correct video processing of 1080/30P, the only difference between 30P and 60i is the fact that the entire frame was captured at the same moment in time, thus eliminating the interlaced problems associated with 60i. Both formats yield exactly 30 frames per second on a progressive display. |
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What a mess. At first I was happy that Blu-ray won the format war because of the larger disk capacity, but now I think it might have been better the other way. |
Aaron I understand what you are saying which is why I still prefer the interlace display. 60i is a lot smoother than 30p it effectively has twice the frame rate on an interlace display. I was just hoping that one day the electronics will be able to emulate what one actually sees from an interlace display on a progressive display. Yes interpolate the missing lines. I still prefer the image from my JVC iART CRT to the image on my Panasonic Plasma. There is more detail in the Panasonic but the motion is nowhere near as smooth as on the CRT and the upscaling of SD from cable is awful. This is not just the Panasonic its true of every set I have looked at so far. In choosing the Panasonic it was the best of the 16x9 sets I was prepared to pay for and it is not as good as the Sony HiScan CRT!!!! I would like the smoothness of interlace and high definition. Just hope that sometime soon the technology will give me what I want. Clearly I am more disturbed by motion artifacts than I am about interlace artifacts!!!!
Ron Evans |
yeah Dave, you've got it right. Yes, those of us without a broadcast station at our fingertips, LOL!, must distribute HD video via BD. And that means 30P in 60i.
And Ron, I agree 100%. Interlaced video displayed on an interlaced set is great because you're talking the native language of the display. When you try to de-interlace for progressive displays, you're manipulating the original interlace stream in a manner in which it was not originally intended to be manipulated. So now you have to create a bunch of voodoo magic to try to make it all work with modern displays. My whole point in this thread is simply to say drop interlacing because we're not using interlaced displays any longer. They're dead. Let's move on to the native language of the displays we're using today, and of course that's progressive. As the MIT expert pointed out in his little blurb I linked to in the HV20/30 forum, there is not one single advantage to using 1080/60i over 1080/30P when the target display is progressive. And actually, there is LESS of an advantage because motion between the two fields makes it more difficult for the compression algorithm vis-a-vis a progressively acquired frame. |
I agree to move to progressive but in that case it should be 60p to match the display completely and get nice smooth motion. Maybe JVC / Panasonic were correct in going with 1280x720P60. Do the displays correctly up scale this to 1920x1080P60 its a 1.5 multiple?
Ron Evans |
Again, agree 100% Ron. That's the best we've got for progressive displays and motion fluidity. But, anyone who's happy with 1080/60i on progressive displays and motion potrayal would also be happy with 1080/30P as long as the display chain properly processed 30P - either properly de-interlacing and frame doubling if delivered via 60i, or simply frame doubling if delivered via ATSC broadcast. And yes, your 1080P sets will scale 720P to 1080P. Of course, you're not getting a true 1920x1080 source frame. But the scaling technology today is pretty good. And there is plenty of competition among chipset manufacturers to insure technology continues to improve in both de-interlacing and scaling.
I understand you're not happy with 60i on a progressive set, so the above 60i vs. 30P doesn't apply to you. |
Last week I shot some footage with my HF10 in 60i, 30p and 24p mode. here is a comparison that should give you an idea how the frame rates compare:
60i: http://www.vimeo.com/960647 30p: http://www.vimeo.com/960652 24p: http://www.vimeo.com/960659 The clips are very short, so better loop them. |
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It will be interesting reading the responses from these manufacturers. |
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Aaron, I mean no disrespect but you haven't provided any sources to back up your assertion that fixed pixel displays produce 30fps output from 60i input streams. I can't prove you incorrect either, but intuitively what you said doesn't seem to add up. How can the following points be explained?
- If displays process 60i as you describe, then half of the motion resolution would just be thrown away for video content that was actually recorded in 60i. I don't know about anyone else, but when I replaced my CRT display with a fixed pixel display, I did not notice any loss of motion smoothness. I would think that a reduction by half would be noticeable. - The latest camcorders continue to record in 60i as their default mode, even if capable of 30p recording. Canon does not market 30p as being equivalent or better than 60i when played back on a "good" display. We know that recording in 30p eliminates deinterlacing artifacts, so why would anyone want to record in 60i unless it provided some benefit in terms of motion resolution? You could argue that this is because there are so many displays that don't handle 30p 2:2 properly, but still I would think that if ANY displays existed on which 30p was flat out better than 60i, then Canon would market that fact. - Our buddy Ken Ross is an experienced video enthusiast who has tested both raw 30p and 60i video footage on a Kuro, which is one of the best displays available. He has clearly said that 60i video looks smoother to him. - The article below notes that some crummy displays simply interpolate each individual field to form a full frame. This results in poor spatial resolution, but the full motion resolution of the 60i input stream is preserved. If crummy displays can retain full motion resolution, I find it hard to believe that good displays would not do likewise. I have not seen any articles that say motion resolution has to be sacrificed to get full spatial resolution. http://www.hometheatermag.com/hookmeup/1107hook2/ - This is pure speculation on my part, but if a good display can properly deinterlace field pairs within a frame, wouldn't it be possible to likewise deinterlace fields from adjacent frames? For example: Input frame 1 field A + input frame 1 field B = Output frame 1 Input frame 1 field B + input frame 2 field A = Output frame 2 Input frame 2 field A + input frame 2 field B = Output frame 3 Input frame 2 field B + input frame 3 field A = Output frame 4 ... This approach would in theory yield 60 unique output frames per sec on the display. It doesn't seem fundamentally different or more difficult than only deinterlacing intra-frame field pairs, other than requiring more processing power because more deinterlacing is being done. |
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"The TV then has to combine these two fields into one frame to display on the screen. Done correctly, you'll see white and black alternating lines. Done incorrectly, you'll see a flashing box that flashes between solid black and solid white." This is inconclusive because the first sentence seems to be saying what Aaron and I have been saying - that the two fields are combined into one single frame, but the second sentence seems to indicate that some TV's line-double each field and display them as individual frames. He is saying both things at the same time. Here is another article that I referenced earlier in the thread that seems to indicate that many if not most TV's de-interlace the two fields into a single frame and then just display the same frame twice (2:2): http://hometheater.about.com/od/tele...80ivs1080p.htm To deinterlace a 60i frame into two true 60P frames would require a deinterlacer that could do motion interpolation. This is complex and requires buffering many frames, it is essentially what an MPEG encoder does. This would be the only high quality way to generate 60 *full resolution* progressive frames where there were only 30 originally, I just don't know if any TV's actually do this, but maybe some do. |
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The real problem is the delivery, which you do mention. It will be interesting to see what you hear from the chip set vendors, but it seems for now the only way of delivering 30P to a TV without first going through 30PsF is to use a PC (i.e., have the PC use the TV as a 60Hz monitor). |
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This is a good read on the subject of de-interlacing by HQV, one of the leading vendors of video processing technology. As you say, you don't believe half of the vert rez is missing from interlaced video while displayed on your progressive set, which means perhaps this blurb is a bit dated, since no one seems to be using non-motion adaptive de-interlacing any longer in these displays or BD players. Quote:
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As to your preference for 30p, so be it, that's why we have choices. For me, 60i provides significantly more of the 'you are there' look. I could care less about trying to imitate the look of film...no consumer video camera can do it even near-convincingly. If I want the look of film, I'll buy a film camera. Videocameras do best what they were designed to do, shoot video that looks like video. Now, if you believe that 30p looks better than anything else on a CRT, so be it. But to me watching a 32" display is not exactly cinematic. It strikes me as very very ironic that the same people who are obviously striving for a cinematic 'look' can only achieve that 'look' on a relatively tiny screen. Not exactly cinematic now is it? But hey, that's just MO. :) |
To be more accurate in my last post, I should have used the term "termporal resolution" rather than "motion resolution".
I'll let this rest for now, but in my mind there is still a lot of uncertainty. For those with camcorders which only record in 1080i, this whole discussion is academic. Shoot in 1080i and just be happy. :) For those with camcorders that also record in 30p, it seems prudent to follow Ken's example and do A/B comparisons of 60i and 30p with your camcorder and your display and see what looks better to you. That's what I plan to do. Thanks guys. |
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