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Canon XL and GL Series DV Camcorders
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Old May 10th, 2008, 08:02 PM   #1
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Canon XL2 image resolution vs DV format

Hi everyone!
I am not sure if I understand the image resolution of XL2. It says that XL2 has 960x576 effective pixels in 16x9 mode.
But as I know DV format cannot have higher res than 720x576.
Is there any possibility to record DV in 960x576 on normal DV tape? Or that higher sensor resolution is being scaled down to 720x576 giving just sharper image in normal DV mode?
Sorry for any spelling errors, I am not english :)
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Old May 10th, 2008, 08:07 PM   #2
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See my article at http://www.dvinfo.net/canonxl2/articles/article06.php

It was written for NTSC but also applies to PAL (change 480 to 576).

The answer is that it scales to 960 for recording to tape.
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Old May 11th, 2008, 08:59 AM   #3
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So would shooting Direct-to-disk maintain the 960x576 effective pixels in 16:9?
And if so, wouldn't it make more sense to just bypass the tape completely?
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Old May 11th, 2008, 09:21 AM   #4
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It might depend on which direct-to-disk solution, but generally speaking, the answer is no. Most all direct-to-disk options are specifically DV format, so the recorded width will never exceed 720 pixels.

If you are looking for a higher-resolution recording, consider an HD format such as HDV. The Canon XH A1 records native 16:9 (which is 1440 anamorphic x 1080) in HDV and costs about the same as the Canon XL2.
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Old May 11th, 2008, 12:27 PM   #5
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Well I am already shooting everything on the XL2, but I'm also running the Adobe Production Suite, which includes OnLocation. I've also been considering the FireStore, is any of this going to get me a higher res?
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Old May 12th, 2008, 03:36 AM   #6
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Quote:
Originally Posted by Andrew Hoag View Post
So would shooting Direct-to-disk maintain the 960x576 effective pixels in 16:9? And if so, wouldn't it make more sense to just bypass the tape completely?
Quote:
Originally Posted by Chris Hurd View Post
It might depend on which direct-to-disk solution, but generally speaking, the answer is no.
So is there any direct-to-disk system that handles 960x576 pixels in 16:9?

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Old May 12th, 2008, 09:27 AM   #7
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To my knowledge, all direct-to-disk or direct-to-edit options that I'm aware of are format-specific, meaning they will record DV at 720x480 (or 720x576) and / or HDV or DVCPRO HD at 1280 x 720 or 1440 x 1080.
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Old May 12th, 2008, 06:27 PM   #8
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To my knowledge, all direct-to-disk or direct-to-edit options that I'm aware of are format-specific, meaning they will record DV at 720x480 (or 720x576) and / or HDV or DVCPRO HD at 1280 x 720 or 1440 x 1080.

It just seems senseless for the XL2 to even have the 950 by 576 pixel ratio if it's going to be scaled down to 750.

Someone needs to get a DTD solution for it. Any programmers or engineers around?
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Old May 12th, 2008, 10:56 PM   #9
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I don't have any links, but I know there are people who will "MOD" your XL2 with a jack that puts out uncompressed video. It basically involves opening up the camera and hardwiring in some jacks that take the image from the CCDs before it gets downconverted to DV.

That's about the extent of my information, but I'm sure you can find stuff by googling. If I recall, the people who do it charge a good amount of money, and with the cost of the XL2 + that money, you could buy an HDV camera.
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Old May 14th, 2008, 11:52 AM   #10
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Yeah, but not uncompressed HD. I'd take uncompressed SD over compressed HDV any day.
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Old May 14th, 2008, 02:39 PM   #11
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Quote:
Originally Posted by Krystian Dobak View Post
Hi everyone!
I am not sure if I understand the image resolution of XL2. It says that XL2 has 960x576 effective pixels in 16x9 mode.
But as I know DV format cannot have higher res than 720x576.
Is there any possibility to record DV in 960x576 on normal DV tape? Or that higher sensor resolution is being scaled down to 720x576 giving just sharper image in normal DV mode?
Sorry for any spelling errors, I am not english :)
"effective" is the key word. The sensors are 16:9 but each horizontal line is sampled at the D1 rate which gives 720 samples per line in the video image. i.e., even though the sensors have >950 pixels horizontal, the signal fed into the compression electronics on the camcorder doesn't have that resolution.

DV only permits two frame sizes: 720 x 480 (NTSC) and 720 x 576 (PAL).

The DV signal carries a marker that tells display equipment whether the video is 4:3, 16:9 or one of a number of other options (2.35:1, 14:9 etc). On a 16:9 display, the image will be stretched and will end up looking like it has a resolution of ~960 x 576. But it isn't that resolution. The resolution is still 720 x 576 - it's just that the pixels are stretched.

As mentioned elsewhere, to get the full uncompressed, native image you have to get to the sensor signals before they are digitized/corrected etc etc.
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Old May 15th, 2008, 07:48 AM   #12
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Originally Posted by Jeremiah Rickert View Post
I don't have any links, but I know there are people who will "MOD" your XL2 with a jack that puts out uncompressed video. It basically involves opening up the camera and hardwiring in some jacks that take the image from the CCDs before it gets downconverted to DV.
I had no luck finding this on Google. Hence, any pointers appreciated.

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Old May 15th, 2008, 10:05 AM   #13
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You may be thinking about Andromeda from Reel Stream. The owner - Juan something - sold it to an unknown buyer, with much conjecture that it was the Red/Scarlet team. There is also unconfirmed news (from a usually reliable source) that he is now working at Panasonic corporate in Japan.

The web site is still up, but you really have to dig to find that they are not actually selling any longer, though DVX's with this mod are being bought and sold like "Penny Blacks".

2-3 years ago (pre-NAB) when I first discovered Andromeda, $2,500 for 4:4:4 out of a DVX, and recording it direct to your laptop, did not seem so outrageous.

http://www.reel-stream.com/andromeda.php
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Old May 15th, 2008, 10:34 AM   #14
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Originally Posted by Andrew Hoag View Post
It just seems senseless for the XL2 to even have the 950 by 576 pixel ratio if it's going to be scaled down to 750.
You mean 960 scaled down to 720. But you have to realize that if it isn't scaled down to 720, then it's not DV. It's not even DVCAM or DVCPRO. It *must* be 720 or it's not DV. See John Miller's excellent post above.

And yes it makes a significant difference by having 960 pixels on the chip and scaling that down to 720 for recording -- that's a sharper, better solution than previous methods which sacrificed vertical resolution.
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Old May 28th, 2008, 09:30 PM   #15
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I believe the key word here is oversampling.

There is a video coverage from this years NAB where John Galt explains the theory of resolution. It is very technical and may be hard to grasp, but everyone interested in knowing how a image sensor works (or should work) would benefit from this knowledge. Especially if they are looking for a new camera.

http://www.freshdv.com/freshtv

Segment: Demystifying digital camera specifications

Last edited by Nik Skjoth; May 29th, 2008 at 09:02 AM.
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