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Canon XL and GL Series DV Camcorders
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Old February 18th, 2005, 01:59 PM   #1
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960x480 widescreen

Hi, I'm getting ready to shoot an out-of-pocket feature on DV for eventual transfer to film, and I'm trying to decide between an XL2 and the DVX-100A. There are a lot of factors in the decision but there is one point I need some advice on.

I'll be shooting 16:9 and the Canon has their "native/true/whatever" 960x480 widescreen target area, while Panasonic does either the digital squeeze or requires an anamorphic lens for their 740x480 CCD. Btw, I'm not worried about resolution per se, or actual CCD size, so don't start on that! The Canon seems like a better choice to avoid the lens complications and the typical digital squeeze but I have these concerns:

I've heard that all DV is 740x480, even on the tape in the XL2... if that's true, what advantage does the 960x480 target area offer? Does it end up working more like the optical (lens) squeeze, as opposed to the digital squeeze, because you're capturing 740 pixels from a wider light area? I can see how that would be better.

If it's not true that DV is always 740x480, and the footage on the tape in the XL2 is truly 960x480, then there's a problem because I understand that any NLE in my price range only captures 740x480 anamorphic widescreen, not true 960x480 widescreen (I know Xpress Pro does this, and their rep claims it's across the board for their competitors). The resolution loss there isn't a problem per se, but I'm worried about resampling at a different rate - could this cause all kinds of digital artifacts and boogers and stuff? Anyone heard about problems like this?

Many thanks!

-Nate
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Old February 18th, 2005, 02:15 PM   #2
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Actually DV is 720x480, not 740x480. This is no different on the XL-2; don't confuse the resolution of the CCD's with what the camera actually puts on tape. I think the following thread will clarify all this: http://www.dvinfo.net/conf/showthrea...threadid=29087
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Old February 18th, 2005, 02:42 PM   #3
 
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Nathan...

I just finished up a 24p, widescreen DV shoot that used both an XL2 and a couple of DVX100's. I editted footage from all three cams down to a 5 minute promo. The XL2 footage was, by far, brighter, more vibrant and clearer than the DVx100 footage. I had to spend quite some time working with the XL2 footage to get it to match the Panny footage.

As for process, the XL2 CCD block is 960x480, however, when you write that to DV tape, it gets recorded as 720x480....that's the DV standard. When I imported into vegas, I had a choice: a-keep the 720x480 DV format, pixel aspect ratio =.909, widescreen letterbox or b-convert back up to 960x480, PAR=1.2121, widescreen, no letterbox. I used option 'a' because it's much more flexible for either 4:3 or 16:9 playback. Both have the same rez.

I'll note that the actual Panny matte didn't exactly fit a 16:9 format. I had to recompose the frame size to exactly match the XL2, which was native 16:9, straight from the CCD block.

We spent some time, before the shoot, color timing the Panny and XL2 together. The XL2 had to be adjusted to match the Panny, since the Panny didn't have near the color adjustability of the Canon.

Unfortunately, I got lazy and left the autofocus on on the XL2 with 20x zoom for part of the shoot. The autofocus exhibited some hunting, not noticeable until I viewed the footage thru a large 13" monitor. never saw it in the XL2 viewfinder. Beware of this if you opt for the XL2.
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Old February 18th, 2005, 07:02 PM   #4
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Thank you both for the invaluable info. That earlier thread had exactly the explanation I was looking for, and the side-by-side comparison of the Canon and Panasonic is extremely useful. Thanks both of you.

-Nate
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Old February 19th, 2005, 10:56 AM   #5
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I'm wondering if this has something to do with the problem I'm experiencing exporting stills and other footage (mpg4).

I shot it with an XL2: 16:9, -3 gain, 24p advanced pull down, some menu tweaks but nothing drastic and a Black ProMist 1/2. In my editor (FInal Cut Pro) it looks perfect. It also looks perfect in After Effects however when I export a still or a quicktime movie it gets "squeezed". I thought this was a problem of rectangular pixels vs. square pixels but I could certainly be wrong. I'm pulling my hair out over this, so any help would be appreciated.

Here is an example of a screen capture right off my editor:

http://www.birthofthecool.com/Testing/still_3b.gif

But that's not what I'm getting when I export. _When I do that I get what you see below:

http://www.birthofthecool.com/Testing/still_1.gif

http://www.birthofthecool.com/Testing/still_2.gif

http://www.birthofthecool.com/Testing/still_3.gif

Thanks!

Matt
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Old February 19th, 2005, 01:15 PM   #6
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Your first link (the screen capture) doesn't open.

Not sure what the issue is, the images are close to the correct size (864x480). If you do the math it's very simple:

480 x 16 / 9 = 853.33

If you do a quicktime export from FCP you should end up with 720x480 pixels, which is correct as far as it's concerned because Quicktime doesn't seem to understand non-square pixels. Resize to 854 x 480 and everything should be correct for display on a square pixel device.

When you edit in FCP the canvas and viewer windows will be correctly proportioned for 16:9 with square pixels. But the output via firewire, or Quicktime export will simply be 720 x 480. You need to view it on a 16:9 capable video monitor if using firewire for your external video device. Or in the case of a Quicktime export you'll need to resize to 854 x 480.

How did you end up with 864 x 480? Actually that's pretty close to being right for square pixels.
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Old February 19th, 2005, 01:20 PM   #7
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How? Well, someone in another thread said 960x480. And then someone on another board corrected me and said it was 864x480. And now of course you're telling me that it's 854x480. :)

I know the first link doesn't work, I've been updating the page as I work on this and thought I had it fixed. I guess I'll have to do it again!

Thank you so much! Do you use compressor to export for DVD? If so, what settings should I use there? Thanks again.

Matt
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Old February 19th, 2005, 01:50 PM   #8
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For square pixels the math is very simple. We want the image to be in the proportion 16/9. We know that the height is 480 pixels. So multiply 480 by 16, then divide by 9 as in my example below. I rounded up 853.33 to 854.

960 x 480 are the pixel dimensions of the CCD. This works out to be the correct proportions for non-square widescreen NTSC pixels. But it really isn't material to anything outside the camera, because that image is downsampled (anamorphically squeezed) to 720 x 480 when written to tape. The 960 pixel width would be meaningless when viewing on a widescreen NTSC monitor, because they are designed to automagically scale the 720 x 480 anamorphic image to fill the screen.

I think that 854 x 480 is the correct size, and in fact it's the resolution of "Enhanced Definition" 16:9 plasma screens http://www.plasmatvbuyingguide.com/p...efinition.html

Sorry, I have never used compressor so I can't help you there...
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Old February 19th, 2005, 04:11 PM   #9
 
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My xl2 is 960x480 exectly...that's the CCD block. Now, if I xapture and render to 720x480, PAR=.909, I get a perfectly displayed letterboxed widescreen on a 4:3 monitor, or a full frame widescreen on a 16:9 monitor. If you're rendering to a DV matte, you gotta use this format.

That same image, when rendered to 960x480, PAR=1.2121 in some format other than DV, will display full frame, widescreen in a 16:9 display, or will display squeezed in a 4:3 monitor.

If you run any PAR/mattes different from this, you'll not get the proper result. A PAR =1.0 is inconsistent with either format.
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Old February 19th, 2005, 07:55 PM   #10
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The 960 pixels on the CCD exist only on the CCD, and they have no relationship to the 720 on tape. The CCD is an analog device, not digital. It gets digitally sampled into a 720x480 frame. You cannot access the 960, they don't exist on the digital tape.

Your DV tape will be 720x480. All DV is 720x480. If it wasn't 720x480 it couldn't be recorded on DV tape (speaking NTSC here only, of course).

When editing, when creating graphics, etc., you always want to use 720x480 with the proper pixel aspect ratio (about .9 for 4:3, about 1.2 for 16:9).

If you go creating graphics at 853 or 864 or 960 or whatever, your editing program will just have to digitally scale/resize it down to 720.

The proper way to work is to treat everything as 720, and if you want to see your footage displayed at the actual aspect ratio, tell your editing program to display the footage with the right aspect ratio (in Vegas, tell it to "simulate device aspect"). That way you'll always be working in 720, creating graphics and titles at 720, etc... no resizing, no stretching, no aliasing, no problems.
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