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Old August 18th, 2005, 01:39 AM   #1
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16x9 CCD question

I am just curious about one thing I noticed in the pdf manual. On pg. 62 under 'Aspect' it talkes about setting the screen size between 16x9 and 4x3 and it says:

"The resolution in the vertical direction (when switched to 16x9) drops compared to 4:3 video."

Now, I was always under the impression that the camera has 16x9 native chips but if the resolution drops when switched to 16x9, that would indicate that the image in 16x9 is cropped (letterboxed) and, hence, the chips are 4x3. If they are/were 16x9 then the image would be cropped on the sides when switched to 4x3 and the vertical resolution would not change, correct?

I could be wrong (and hopefully am) but it is confusing.
Any ideas/explanations?

Thanks, Jiri
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Old August 18th, 2005, 02:33 AM   #2
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IINM, the JVC HD1 used 4:3 chips, and extracted a 16:9-shaped patch out of the center of it (the same technique used by the XL2).

I believe the HD100 uses the same chips. I have no confirmation of that from any sources other than viewing the footage, but I do think (until told otherwise by someone who can verify) that the chips in the HD1 and the HD10 and the HD100 are all the same. Which would make it a 4:3 chip, and the behaviour would match what you describe in the manual.

That doesn't mean they're not 16:9 native. That just means they wouldn't be physically shaped 16:9. The HD100 still delivers full native resolution out of its 16:9 patch off its 4:3 chip -- there's no digital stretching or resizing going on, as happens in non-native cameras.
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Old August 18th, 2005, 05:26 PM   #3
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The CCD block is indeed 4:3 "in shape" (which confused one of our D.O.P's for a moment or two).
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Old August 19th, 2005, 11:58 AM   #4
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Someone test this, please...

Then, there is another question; does the camera use the FULL 4x3 block for its 4x3 aspect ratios and crops that to 16x9 by turning off the top and bottom? If yes, then we are getting less resolution in HDV and all 16x9 aspect ratio modes. Why?

As for testing this, someone who already has the camera can easily find out for us by doing the following:
1. in 4x3 frame a shot so that you can clearly see the edges, i.e. a door frame, window, etc.
2. switch to 16x9 and see what happens to the frame

If you see more to the sides, then we are getting more overal resolution in 16x9. If we see more on top and bottom and the sides don't change, then the camera is cropping the resolution for 16x9 (and as a result HDV) and I wonder if we are not getting cheated on resolution and also by the claims of 'native' 16x9 - because it would be not.
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Old August 19th, 2005, 12:01 PM   #5
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I guess a footnote question would be; doesn it matter? I seem to recall when I shot a while back with CineAlta that it showed a 4x3 aspect in the viewfinder and cropped the aspect to whatever is selected...so perhaps it's not that much of an issue?
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Old August 19th, 2005, 12:02 PM   #6
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From what I've heard and read, you get true square pixel 1280x720 resolution. The actual chip is simply bigger than that.Thats been one of JVCs marketing points. As to recording 4:3, I wonder if that is cut down or uses the full chip?
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Old August 19th, 2005, 01:34 PM   #7
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Jiri, if that test proves that the camera is native 16:9, and if Barry is right and the camera uses the same chips as the HD1 I can assure you it does have more space to the left and right. I've always noticed that on my HD1 when switching between DV and 480p/720p.
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Old August 19th, 2005, 02:21 PM   #8
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Thanks guys.

I guess the 'red flag' of concern is the line in the manual "The resolution in the vertical direction (when switched to 16x9) drops compared to 4:3 video.", but perhaps, that's a mistake on th epart of the technical writer. It wouldn't really make much sense because the vertical rezolution for NTSC DV shouldn't be other than 720 and if the HDV rez is 1280x720 as they say then the top and bottom part of the 4x3-shaped chip should not be used in any mode, hence making it 16x9 native.
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