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General HD (720 / 1080) Acquisition
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Old March 8th, 2006, 12:34 PM   #46
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It's always a good discussion, and it's great that you're getting multiple educated points of view. Douglas really knows his stuff, and so do I, and that we disagree should be taken as that there's not a simple answer to the question, not that either of us is necessarily wrong. If our comments stop and make you think, then that's the best result by far :-)

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Old March 8th, 2006, 01:05 PM   #47
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Unprofessional language does not lend credibility to one's opinion.
C'mon... Even George Lucas drops the F bomb. I remember right after Return of the Jedi came out, he was saying " What was I thinking? It's nothing but a bunch of F'ing muppets!"
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Old March 8th, 2006, 01:38 PM   #48
 
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Originally Posted by Graeme Nattress
Getting rid of interlace should have been the first step to HD, not the last!!
I agree in theory, but in practice, progressive wasn't even on the plate when the HD spec was developed, nor when the Grand Alliance proposed it, nor when it was officially accepted.

Additionally, had the Grand Alliance had their sh** together, we never would be hearing of 720p, as 720p was intended as an interim, and as history would have it, it will be indeed, an interim format, which is the main reason I'm mostly a 1080 guy. We do have 3 720 cams, we use them a lot, and have scaled them a lot. We first noticed problems on a 60" SXRD monitor at Government Expo, and one of our major clients needed vid for their tradeshow. They took the 720p acquired and delivered footage, viewed it on their Samsung 70", and told us they were unhappy. We reshot the same footage using 1080, and they were happy, and it ended up on 10 screens at CES in January. That whole real-world process is what caused us to dig in deeply, and really stretch what we could do, even buying two different 1080 displays and borrowing a Qualia projector to rip into the footage. (This client is seriously important to us, obviously) I will say that in the process, I've learned that scaling isn't as easy as one might think. While scaled vid looks great on displays smaller than 40", it exponentially increases in view-ability post 60", and gets worse when blown up with a large projector and screen. Especially look at the edges, which are somewhat hidden by bezels on many displays.

Additionally, the discussion of "real" vs "perceived" becomes one of opinion, and at the end of the day, we're really stuck with that. "Really," what Panasonic has done with the HVX simply shows it can't work, on paper. But perceptually, it's a very good camcorder. so what is "real?" Given DSP on both mentioned camcorders, either one can be shown to best the other, depending on a number of variables.

Like Graeme says, just the mere fact we can't agree on what we're seeing or doing, says a lot. I'll stick a dig in here though, and point out that what we see here on our screens, is identical what Poynton has written about in several papers and his "bible" of HD. I have to chuckle though, because when you see guys like Faroujda commenting that you can't deinterlace footage all that well selling deinterlacing devices, and you see Terranex, S&W, Miranda, etc all coming on with very well-made products...some manufacturer has an agenda in the industry.

1080 is the future, whether we need to debate semantics, processes, or actualities of the media conversions.
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Old March 8th, 2006, 01:57 PM   #49
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Originally Posted by Ken Hodson
Considering the FX/Z1 arguably capture less detail/true resolution then the 720p HD100, then is de-interlaced for 1080p, I find the math/logic very hard to buy.
If I recall correctly, resolution-chart tests show the FX1/Z1U having a slight edge over the HD100U in terms of actual recorded detail. Not nearly as much as the theoretical difference in overall resolution would suggest, but enough to make 1080i workable for either 720p or 1080p output. It makes more sense to me that 1080i works as a successful compromise than to expect 720p to upsample well to 1080p.
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Old March 8th, 2006, 03:26 PM   #50
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are we not kind of comparing different cameras here instead of really just the format?

The only true way to test the formats is to take a scene from the same camera but in both formats. I know this is impossible right now.

One thing I have done however is made a scene in 3D Studio Max to match a real world setting. I then rendered at 720p and 1080i with the intent of converting both to 1080p. The 720 was slightly softer but had much less artifacts. The scene I rendered had many thin line objects such as power lines and low angle edges.

One thing that was hard for me to test however is the interlace filtering that interlace cameras always have. Any filtering of the image I did quickly killed any extra detail the 1080i had over the 720p. I know this isn't a god test in terms of what cameras do but it does tell me what can be done with raw images of certain resolutions and aspect ratios. My outcome is that 720p is softer but much cleaner. I personally would rather have a slightly softer image but with no missing thin details or aliased edges. I personally think people are looking for way too much detail. Who really wants to see every single blemish and imperfection?


Douglas what cameras were you using for your client that were shown on those 60" displays? Perhaps it was more of a certain look to the 1080i cameras and really nothing to do with the 720p format. You can take 4 different 1080i cameras and they look all look very different. The JVC HD100 for example does have a slightly more smooth filmic look to it which some people who are used to the crispness of video might not like. It doesn't mean it has less detail but just a different look and style. If you used a highend 2/3" 1080i camera compared to a prosumer 1/3" 720p camera well no kidding there was a boost in detail between the two images. If you used a HD100 compared to a Z1 I cannot see any way on how there could be more detail.

Considering a lot of people think a progressive scan SD DVD is HD on a 60" HDTV I think it is going to be a long time before people start choosing a 1080 image over a 720 image (if somebody didn't just try selling them the numbers first)

The are only two areas where I consider 1080i HDV to have an advantage.

1. smoother motion at 60/50 fields per second. Hopefully this will change when we get 720p 60p.

2. Even though 1080i has more compression per pixel the compression artifacts are not blown up as much. Mpeg2 artifacts at 720p can show up more when scaled up to 1080p.


For those interested on the points of Graeme and Douglas you should check out Steve Mullen's view on 720p HDV vs. 1080i HDV. Most of his tests show many 1080i cameras to have less detail than the 720p from the HD100.
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Old March 8th, 2006, 05:19 PM   #51
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Quote:
Originally Posted by Kevin Shaw
If I recall correctly, resolution-chart tests show the FX1/Z1U having a slight edge over the HD100U in terms of actual recorded detail. Not nearly as much as the theoretical difference in overall resolution would suggest, but enough to make 1080i workable for either 720p or 1080p output. It makes more sense to me that 1080i works as a successful compromise than to expect 720p to upsample well to 1080p.
I would highly recommend the HD shoot-out article by Adam Wilt at
http://www.dv.com/
titled "Four Affordable HD Camcorders Compared" under "Top Stories on DV.com".
This article leaves me with no dillusions that when converting to a 1080p image, 720p JVC HD100 would produce a better image than the interlaced Sony's.
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Old March 8th, 2006, 06:39 PM   #52
 
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While it might not leave you with any delusions about converting, I don't see the relevance. They didn't didn't convert anything in the shootout test to be viewed on scaled or native monitors. Additionally, I believe enough murkiness has been thrown over that particular test to cause it to not be of merit.
Additionally, the conversion is heavily dependent on the algorithm used for the conversion. What may convert well from one system won't convert well for another. For instance, Graeme brought up using a polynomial set. Polynomials are generally not usable for video because it's not consistent with the limited range of video. There are many variables, and many theorems about how this could, should, would be and *is* done. How many taps? From where is the output sample value derived? 8 bits? 10 bits? 12 bits processing? How far is it oversampled?
Looking at a res chart and not being disillusioned about scaling values is like looking at a gas tank and suggesting you know how fast the car can go.
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Old March 8th, 2006, 07:24 PM   #53
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Quote:
Originally Posted by Thomas Smet
are we not kind of comparing different cameras here instead of really just the format?

The only true way to test the formats is to take a scene from the same camera but in both formats. I know this is impossible right now.
Very true, and the camera needs to be potentially higher quality than the formats being considered.

I think it is possible to say three things:

1/ 1080 is better than 720

2/ Progressive is better than interlace.

3/ 50fps gives better motion rendition than 25fps

The obvious conclusion from that is the best format (given a good enough front end) must be 1080p/50, and I don't think anyone seriously can disagree with that. The problem is that that is a huge challenge for todays technology, and that necessitates making a compromise with at least one of those points. (At present.) The big debate is normally whether to accept going down to 720, OR accepting the problems of interlace. Which is the least bad compromise - 1080i or 720p.

That's why I'm surprised the third option isn't more discussed of in these forums - 1080p/25, which is what I believe most top end TV drama etc is being shot in currently (for delivery psf). It keeps the undeniable advantages of 1080 resolution and progressive scan, and for drama many producers actually like the temporal look - "film like".

Assuming you have a camera front end that can deliver the goods.
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Old March 8th, 2006, 08:56 PM   #54
 
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Originally Posted by David Heath

That's why I'm surprised the third option isn't more discussed of in these forums - 1080p/25, which is what I believe most top end TV drama etc is being shot in currently (for delivery psf). It keeps the undeniable advantages of 1080 resolution and progressive scan, and for drama many producers actually like the temporal look - "film like".
.
This was discussed and debated ad nauseum in another thread in this forum, and while I happen to agree with you...doesn't matter, I guess. Did anyone catch Scott Billups recent comments about the Canon shooting a nicer image than the CineAlta 900? I'd have a hard time with that unless I saw it, but Billups is incredibly capable, and has been doing digital cinema longer than most folks here have been saying "DV." He specifically commented on the detailed smoothness found in the 1080i stream and the sweetness of the 24pf image. Pf is basically just deinterlacing in the cam vs in post, and a good deinterlacer can do exactly the same thing, potentially better due to more horsepower and no time constraints, plus multipass.
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Last edited by Douglas Spotted Eagle; March 9th, 2006 at 09:52 AM. Reason: typo
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Old March 9th, 2006, 05:40 AM   #55
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Originally Posted by Douglas Spotted Eagle
Psf is basically just deinterlacing in the cam vs in post, and a good deinterlacer can do exactly the same thing, potentially better due to more horsepower and no time constraints, plus multipass.
I don't think psf is "basically just deinterlacing in the cam vs in post" - it's a way of carrying a TRUE progressive image over an interlace system, exactly the same as film telecined in PAL. Most importantly, it's possible to seamlessly go between psf and p - the difference is solely the order in which the lines are presented, no scaling etc is required at all. For progressive you transmit lines 1,2,3,4.....1078,1079,1080, and for psf the lines are transmitted 1,3,5,7.......1077,1079 (new field) 2,4,6........1076,1078,1080. To go from psf to p you simply reorder the lines, to go from i to p requires a de-interlacer and heavy processing.

What it means in practice is that the same transmission structure is used for both psf and i, and whether the origination is interlace or progressive can be chosen on a programme by programme basis, such as interlace for sport and progressive for drama (for delivery psf).

I'd be interested what Graeme thinks of this?
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Old March 9th, 2006, 06:43 AM   #56
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PSf is exactly as you describe David, a way of trasmitting progressive video carried in an interlaced video carrier. It's not any form of de-interlacing.

The Canon doesn't shoot Psf. It shoots a so called "24f" mode which to me looks like 48i roughly de-interlaced.

David, you're right that if you want a filmish look, 25p, or 30p is just fine, but no affordable HDV camera shoots those rates other than the JVC with it's 720p30. All the 1080i cameras have fake progressive modes, some better than others, but all faked from interlaced chips. Even thinking that 1080i will deinterlace to 1080p and give a result approaching real 1080p forgets that 1080i has about 30% less vertical detail than 1080p, and even best de-interlacers don't put that back in. People say you can think of 1080i60 say as 540p60, but really it's more like vertically wobbled 378p60. The faked progressive modes on the 1080i cameras turn of interlace filtering, so you can get 540p, but only at rates up to 540p30, not 540p60.

And although I like the 24p/25p film look rates, I really like the 50p and 60p rates also. They have a certain luxuriousness to them that's very apealing, and a certain creamyness that 50i / 60i lacks.

David, you're list is correct - P is better than I, 1080 is better than 720, 50fps is beter than 25fps, but....

1080i only has the SAME vertical resolution as 720p due to the interlace factor, so, if you were to rate formats in terms of qualtiy based upon that list you have to take that into account. From what Sony were describing to me, the new XDCAM HD will shoot 50p or 60p, but at (perhaps less than) half vertical resolution. They couldn't tell me if interlace filtering can be turned off. Basically, in overcrank you get 540p, probably embedded in 1080i. Nothing is ever simple.....

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Old March 9th, 2006, 06:48 AM   #57
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Originally Posted by Douglas Spotted Eagle
I have to chuckle though, because when you see guys like Faroujda commenting that you can't deinterlace footage all that well selling deinterlacing devices, and you see Terranex, S&W, Miranda, etc all coming on with very well-made products...some manufacturer has an agenda in the industry.
I chuckle at that one too, but I think it's more like Faroujda saying "We make the best de-interlacers, and still they're not perfect. What's a better waste of R&D money, figuring out how to make de-interlacers' perfect, or just ditching interlace and going fully progressive everywhere?"

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Old March 9th, 2006, 09:18 AM   #58
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Originally Posted by Graeme Nattress
David, you're list is correct - P is better than I, 1080 is better than 720, 50fps is beter than 25fps, but....

1080i only has the SAME vertical resolution as 720p due to the interlace factor, .....
Thanks Graeme - my list was to individually compare p v i, 1080 v 720 etc - I was NOT comparing 720p v 1080i, as I hope you realise, and it still surprises me why the discussion is so often just between those two choices, with 1080psf/25 so little mentioned. With the right camera (true 25p), and if "film motion" is seen as good, this must be the best compromise?

I was also only thinking of transmission formats from a broadcast perspective, and here think 1080 i or psf has a lot to commend it for the present time. That is not the same as saying any individual camera using any recording format is better than another solely because of that. Format comparisons need to be divorced from camera comparisons, and vice versa.
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Old March 9th, 2006, 09:27 AM   #59
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Douglas- ( alittle off topic ) you reminded me of checking out www.pixelmonger.com to see if Mr. Billups has updated his site. The man is in serious need of a webmaster. He's about 3 years ( light years in todays market ) behind. Maybe he's working too much ! It was a relevant source. Now it should be in the Smithsonian. Kurth
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Old March 9th, 2006, 09:51 AM   #60
 
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Originally Posted by David Heath
I don't think psf is "basically just deinterlacing in the cam vs in post" - it's a way of carrying a TRUE progressive image over an interlace system, exactly the same as film telecined in PAL.
Of course you're right, and my intent was to refer to the Canon and typed Psf instead. I've modified my post to refer to the Canon, which as Graeme mentions, is a deinterlaced frame (pf)

Kurth, I get to see/listen to Scott once a year at NAB...maybe I should mention his website, but chances are (knowing the kind of guy he is) he won't care. It's not really part of his very focused world.
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