So, here's the thing ...

Can I throw something back in? With the caveat that I don't have a technical background and I respect the superior knowledge of many folk here.

I agree that the maths doesn't add up. Logic tells us that we can't 'see' more detail than the pixels we are viewing. However, the problem is not as simple as comparing this with getting a high res image and simply downonverting to a lower res image. There are so many complicating factors in the encoding process between DV and MPEG-2 that just don't figure in the simple Hi-res to Lo-res maths argument. Surely?

For example, is it not so that the best resolving power that the DVX can supply is no more than 380 lines? You can't tell me that the encoding process is uprezzing that to the full 480. Some degrading must occur. My point is that the resolution of SD STARTS this side of ie. LOWER THAN 480 lines. On the other hand HDV resolution starts the OTHER side side of 480 lines, therefore more detail will be preserved. In other words (OMIGOD I COULD BE SO WRONG) :embarasse the proper comparison in a still image in Photoshop would be to take a lower res image than your final output and uprezz it and take your comparison Hi-rez image and down-res to the final output. Which one would now be the better quality image?

Oh, happy Easter, by the way :beer:
 
Actually, here's a resolution chart shot by a DVX in 24p:

24p3lx.png


In progressive mode, the DVX resolves 480 lines. In interlaced mode, it may be closer to what you say.

Barry estimates that the Z1/FX1 resolves about 770 lines in 1080i mode.
 
I have to agree with what Barry is saying, once you throw data away by downsampling or limiting bandwidth in audio it's lost and there's nothing that can be done to bring it back.
But static resolution charts don't tell us the whole story and using black and white charts tell us even less.
Here's a simple test. Take a detailed digital still image, something with lots of fine colour detail. Print it out at the max res onto photo paper. Down the res in PS, print that out, down the res again and do the same thing.
Now take say a DVX100 and track accross those photos, bet you can see the difference even though when the resolution of two of the images is higher than the native res of the DVX 100.
Now I don't have a simple explaination for this but I suspect it may have something to do with harmonics and our brains ability to fill in missing detail.
 
robroysyd said:
But static resolution charts don't tell us the whole story and using black and white charts tell us even less.
Click to expand...

It wasn't meant to show anything other than the resolution of the DVX in progressive mode, answering a direct question exactly on that point.
 
But there is far more to resolution that just spacial res, its called temporal and its the same thing that allows a SD set to look like a HD set.
 
Walter_Graff said:
But there is far more to resolution that just spacial res, its called temporal and its the same thing that allows a SD set to look like a HD set.
Click to expand...

I was addressing a question about vertical resolution only.
 
OK, so now I'm really confused.

In search of enlightenment I turned to Barrys' DVX DVD. I've just been watching it. On it there is a direct comparison - ON DVD - between the image of the DVX and the JVC HD1. How come, on your own DVD, Barry, the resolution of the HDV footage shines through compared to the DVX? :huh:

I'm sure I must be miising something - but I'd like to know what it is ...
 
The demo on the DVX DVD was of DVX footage uprezzed to HD. A small segment of the frame (that could fit in a standard def screen was then compared. So we're talking the opposite process :).
 
The HD1 footage is extremely sharpened in-camera. The DVX footage was shot on detail level -3 or so. The HD1 was not able to adjust the sharpness. If we'd set the DVX on +7 detail level, it probably would have looked the same, but that's not the look we wanted. And at the time that we made that footage (that was shot in 2003) we didn't know how to extract the most from the DVX settings, so we were just using the DVFilm film-transfer default settings.

On the FX1, the sharpening comes at a default of either +11 or +12 (out of 15), don't remember exactly. That would correspond to probably +5 or +6 on the DVX. That's why I keep saying, you have to make sure that all other things are equal; you can't just shoot an FX1 on default and a DVX on default and say "see, there's proof -- the FX1 is sharper", because with a little tweaking in the menus you could make the DVX substantially sharper and the FX1 incredibly softer.

But with the JVC there was no option, it comes as edge-sharpened as I've ever seen any camera, and it's non-adjustable.

Here's an example of how much difference sharpening makes. Here's the DVX at -7, and at +7:
DVX-detail-comparison.JPG


The only difference between those shots was the setting of the detail level, everything else was identical. Obviously the detail level makes a huge difference, and if you're comparing -7 to +7, someone's going to think "wow, that +7 is a lot sharper!" Well, that's the comparison you saw on the DVD, -3 vs. probably +12 (by comparison) for the JVC.

I guarantee that if I were to re-shoot that footage now, the results would be *substantially* different!
 
Man, this fun little discussion/challenge turned back into a science fair. lol

You guys sure know how to take the fun out of what we do. *smile*

Hey Barry.....it's all good. fact is, you know waaaaaaaay more then I do anyhow, and can probably shoot circles around my last 3 DP's. It's all perception.

- Shannon W. Rawls
 
Can't help it -- probably my background as a computer programmer. I have to know what is *actually happening*, rather than just taking somebody's observation and believing whatever they say, or just buying into "conventional wisdom." I'll put anything to the test, and I don't care whose side "wins", as long as I can figure out the what and why.

Some people don't care about the what and the why, but for some of us, discovering that is essential. Different strokes for different folks, I guess.
 
ShannonRawls said:
You guys sure know how to take the fun out of what we do. *smile*
Click to expand...

I really hope not Shannon. But as you also said, it really is about perception and maybe words are just not going to be enough to resolve (:grin: ) the argument.

Actually I have resolved (OK that's eneough) to stick with my DVX. Resolution isn't everything and I know that with attention to detail and Barry's book under my arm I will get some stunning footage onto DVD.

Thank you, Barry for taking (as always) the trouble to explain the detail behind what may be impenetrable to mere mortals such as myself. I still haven't got a handle on what enabled the HDV footage to make such an impression on me when mathematically it doesn't make sense. But I've been picking at this for too many days now and it ain't worth lying awake at night thinking pixels - so I'm learning to stop worrying and love the DVX - until the HDX, that is.
 
Michael_Bott said:
Actually I have resolved (OK that's eneough) to stick with my DVX.
Click to expand...

A wise choice! I didn't own any cam when I went with the FX1, and I think that's the sensible choice (for me) as I move ahead with my work. That said, there's no way I would upgrade from the DVX yet; not until I had to.

But if you're buying a cam without owning one already, *that's* when you should consider a Sony or an HDX. HD editing and all of its freedom (via the extra rez to crop and adjust for SD) is a blast!
 
For making films however; I'd wait for HD 24p (In our price point of course). HD 60i is, well...

Oh nevermind; damn this circle!
 
"Can't help it -- probably my background as a computer programmer"

lol

I understand the feeling, i'm a part time Engineer/inventor/electronic hobbyist/computer programer (assembly langauge Z80 no less in pure binary from op code look up book on the STK80 emulator{back in the Cambridge days/<well was on five years back>})/ artist/ philospher/ i.e. jack of all trades expert at none!

*oops must dash its 2:28 am in the morning and i STILL have'nt completed my thesis..*
 
Been away for a few days and missed a good debate.

Michael Bott and Shannon, I know exactly where you are coming from.
I was out in the garden last week with the first bit of decent weather. Did a few shots of some plants, cows in the field next to my house, a few shots using a new Century Optics diopter. In all about 15 mins of footage. PLayed about with it in FCP, then into DVD Studio 3 and burned a dvd.

Played it on my Pioneer dvd player via HDMI into my Pioneer 43 HD Plasma.

Blew me away. And this is SD we are talking about. Quality is superb. Looks like HD but is not. Surpasses the quality of Return Of The King Extended DVD. And just wait till Blu Ray comes out later this year or early next!
 
Steve Shovlar said:
And just wait till Blu Ray comes out later this year or early next!
Click to expand...

well i'm not sure it's been decided what the Hi def disc will be yet. we have Blu Ray competing with HD-DVD. I'm not sure a single standard has been reached yet.
 
DVD playing FX1 image

DVD playing FX1 image

I gave up looking for explanation on what makes my FX1 produce such good DVDs. Everytime I look at the DVDs I make from the FX1, I am very impressed. If it's not a resolution issue, it might be a couple of other things.

1. It's doesn't work with DV codec. DV really messes things up. I completely bypass that codec and go straight from MPEG2 to Apple Intermediate to MPEG2. When I look at the same frames after converting to DV, several problems appear, including issues with colors (and horrible when you have strong colors).

2. It's real 16/9. People make 2 kinds of DVD from 16/9 footage: they make real 16/9 or they make 3/4 footage with black lines. In both cases, you are working with high resolution footage from original 16/9. No stretching and funny business. Even there, I completely bypass the horrible SD DV codec with its fixed resolution.

The MPEG2 source could also explain why I manage to encode better video for web from HDV than from SD, even if the resolution is lower. I typically deliver my web video at 480x270 in Sorenson 3 pro. If I do the same thing from SD, at comparable resolution, the quality is usually not the same. And again, if I take SD resolution footage from a commercial DVD and make a simiral file for web publishing, it will usually look even better than my FX1 footage.

And I'm here in Europe, where DV codec has a better color space to work with than NTSC DV. I think I would really hate to look at NTSC DV footage.

Codec matters.

By the way, I hate Canopus procoder. I find its deinterlacing is not that good and it's known for converting between PAL and NTSC. When I tried from interlaced footage, it always came out with funny results.
 
I'm a broadcast video engineer by trade, and recent DVX buyer, and have been following the SD DV/HDV debate with interest. Although competent technically, am a bit rusty on the first principles theory, so would welcome input from current acknowledged experts (without brand loyalties).

I wonder if there's any mileage in inviting people like Adam Wilt to pitch in. He seems to be very strong on the theory and not particularly brand biased. It would be great if he could be there for your shootout to validate the methodology.

Unfortunately, there are so many variables and restrictions on comparing like-for-like that it's very easy for one or more overlooked factors to swing the results.

One other thought:
We probably all agree that lens quality is a significant factor. The DVX has a good lens, but has to have been designed down to a price, which means it won't compete in terms of absolute resolution, control of flare, aberrations etc. with a broadcast/film lens costing much more, or even a lens designed for more expensive DV cameras like the DSR570. The designers would have taken into account mechanical complexity, cost of components, and electronic processing compromises further down the chain. Knowing it was destined for SD, they would not have bothered to have the lens capable of resolving more detail than SD can handle, and knowing it was going to be chroma bandwidth limited by DV coding, further compromises may have been allowed. So MAYBE the DVX lens somewhat compromises the quality that the image sensor and recording system could theoretically directly deliver?

Then along comes HDV. The lens brief has similar cost restrictions, but the minimum acceptable quality has to be higher to cope with the increased image sensor resolution and although still severely chroma bandwidth limited, it must be higher than for SD DV. In fact, a similar higher quality threshold must apply to the downstream electronics.

Put it another way. Say we shot a wide angle landscape shot. DVX/PD170 SD footage typically wouldn't resolve fine detail in the distance very well, but we know a more expensive DSR570 DV camera and more expensive lens would do much better. So we know the standard £3000 DV camera chain is quality compromised.

The new HDV chain is also compromised, but must be less so than DV. So it's a matter of LESS compromise! Perhaps the downconverted HDV merely approaches the maximum theoretical quality SD DV is capable of, more closely? Compare studio monitor PAL picture with the same PAL picture connected to a domestic TV, and although both SD, they ARE chalk and cheese!

Damn... I hope I'm wrong, as it might have swung my buying decision, much as I love Panasonic and the DVX for pushing the market envelope and giving Sony a kick up their complacent arses!
 
eric, you make some very legitimate points. I can see good arguements for either is the problem though! The DVX is able to resolve more than the limit of the DV format so that shouldn't be much of a factor. In the downres process you would loose most of the benefit of a sharper lens (if not all). Still... hard to say. I'm not entirely convinced that a broadcast lens would perform all that better than the standard DVX lens. It would be interesting to compare! Surely they will have different MTF ratings. Hmmm.... interesting...

The things we need to account for when we talk about lenses are:

1) Sharpness (limited by the format)
2) Contrast (NOT format limited)
3) Color rendition
4) Aberrations

not sure where that leaves us!
 
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