XL2: 16:9 or 4:3?
- Thread starter FatBird19
- Start date
This stolen from an article
mikkowilson
Steadi-Guru
I find it amusing that Canon actually advertises the camera a BOTH 16:9 *and* 4:3 native. :huh:
Of course there's the irony that's it's actually not using the chips natively for either! :cheesy:
- Mikko
Of course there's the irony that's it's actually not using the chips natively for either! :cheesy:
- Mikko
Barry_Green
Moderator
The XL2's physical chip shape is 4:3.
However, they never ever ever use the top and bottom 25% of the chip, they only ever sample the middle 16:9-shaped patch. So does that make it 16:9 native? Sure. I mean, what would be the difference, if you were to take a pair of tin snips and snick off the top and bottom of the CCD? You'd end up with a 16:9-shaped CCD. Well, that's what they use. They sample 16:9 off the chip at full resolution.
The question mark then becomes what the size of the CCD is. Probably shouldn't say it's a 1/3" CCD because a good percentage of it isn't being used, so maybe better to describe it as a 1/3.333" CCD.
As for 4:3, they do not expand back up to the full size of the 4:3 chip. Instead, they crop off the left and right sides of the 16:9 patch to create a 4:3 extraction.
The net result is that in 4:3 mode, the XL2 is using a patch of CCD that's equivalent to a 1/4" CCD. But the pixel count within that patch is still full resolution for a 4:3 frame.
So -- yes, it should qualify as both 4:3 and 16:9 native, since there is no digital interpolation going on to create either aspect ratio.
However, they never ever ever use the top and bottom 25% of the chip, they only ever sample the middle 16:9-shaped patch. So does that make it 16:9 native? Sure. I mean, what would be the difference, if you were to take a pair of tin snips and snick off the top and bottom of the CCD? You'd end up with a 16:9-shaped CCD. Well, that's what they use. They sample 16:9 off the chip at full resolution.
The question mark then becomes what the size of the CCD is. Probably shouldn't say it's a 1/3" CCD because a good percentage of it isn't being used, so maybe better to describe it as a 1/3.333" CCD.
As for 4:3, they do not expand back up to the full size of the 4:3 chip. Instead, they crop off the left and right sides of the 16:9 patch to create a 4:3 extraction.
The net result is that in 4:3 mode, the XL2 is using a patch of CCD that's equivalent to a 1/4" CCD. But the pixel count within that patch is still full resolution for a 4:3 frame.
So -- yes, it should qualify as both 4:3 and 16:9 native, since there is no digital interpolation going on to create either aspect ratio.
mikkowilson
Steadi-Guru
(Without starting a resolution flamewar) :violent5:
But, even with oversized chips, only one of those modes can use the pixel aspect ratio of the chips. Only one mode will user a native 720 x 576 pixels on the chip. - The other may be oversampled, but it's still scaled in one direction and not truly native.
Right?
- Mikko
But, even with oversized chips, only one of those modes can use the pixel aspect ratio of the chips. Only one mode will user a native 720 x 576 pixels on the chip. - The other may be oversampled, but it's still scaled in one direction and not truly native.
Right?
- Mikko
Barry_Green
Moderator
Well, see, now you're getting into the whole pixels vs. pixels thing. CCD pixels are not directly 1:1 relatable to frame size pixels. And you can have more, or fewer, and still get full resolution out of your frame.
Most 2/3" broadcast cameras that shoot 16:9 appear to have 960x480 pixel CCDs. 960 isn't 720, yet when they sample and compress their image they make a 720-pixel frame.
Again, CCD pixels are not directly readable by the system. There's no way to find out what a CCD pixel's charge is. It's not like CMOS. CCD pixels are analog wells, and the only way to read it is by getting an analog feed off the system, and digitizing that analog feed. So think about it in terms of audio -- a microphone outputs an analog voltage signal, which gets sampled at 48000 times per second into the digital domain, but nobody asks "how many samples does that microphone output?"
CCDs are to video as microphones are to audio. It outputs a voltage wave, not pixel data.
Most 2/3" broadcast cameras that shoot 16:9 appear to have 960x480 pixel CCDs. 960 isn't 720, yet when they sample and compress their image they make a 720-pixel frame.
Again, CCD pixels are not directly readable by the system. There's no way to find out what a CCD pixel's charge is. It's not like CMOS. CCD pixels are analog wells, and the only way to read it is by getting an analog feed off the system, and digitizing that analog feed. So think about it in terms of audio -- a microphone outputs an analog voltage signal, which gets sampled at 48000 times per second into the digital domain, but nobody asks "how many samples does that microphone output?"
CCDs are to video as microphones are to audio. It outputs a voltage wave, not pixel data.
mikkowilson
Steadi-Guru
Barry, you made me feel stupid for over looking something obvious again... :dankk2:
You are, as normall, totally right.
Then begs the real question: "What defines 'native' resolution?" :huh:
...And, the original question, "is the XL2 16:9 or 4:3?": Is the answer "yes" or "no" ?
- Mikko
You are, as normall, totally right.
Then begs the real question: "What defines 'native' resolution?" :huh:
...And, the original question, "is the XL2 16:9 or 4:3?": Is the answer "yes" or "no" ?
- Mikko
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Barry_Green
Moderator
Well, "native" resolution has typically been used in context with digital stretching/squeezing. So a DVX is native 4:3, and it uses digital stretching to accomplish 16:9; hence "fake" 16:9 (same as XL1 and VX2000 and basically all pre-Panasonic PV-DV953 cameras).
The XL2 qualifies as "native" in that it doesn't do any digital stretching for either aspect ratio, it samples each aspect ratio off the CCD (as does the HVX and the Z1 and basically all the native 16:9 cameras). Some 4:3 cameras do the same thing too; the PDX10 and GS400 and PV-DV953, for example, have 4:3 CCDs but they sample 16:9 signals off the chip instead of doing an after-the-fact conversion.
So the answer to the XL2 is "yes". But in 4:3 mode you're getting the equivalent of a 1/4" CCD, and in 16:9 mode it's the equiv. of a 1/3.333" CCD.
The XL2 qualifies as "native" in that it doesn't do any digital stretching for either aspect ratio, it samples each aspect ratio off the CCD (as does the HVX and the Z1 and basically all the native 16:9 cameras). Some 4:3 cameras do the same thing too; the PDX10 and GS400 and PV-DV953, for example, have 4:3 CCDs but they sample 16:9 signals off the chip instead of doing an after-the-fact conversion.
So the answer to the XL2 is "yes". But in 4:3 mode you're getting the equivalent of a 1/4" CCD, and in 16:9 mode it's the equiv. of a 1/3.333" CCD.
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mikkowilson
Steadi-Guru
"AAHA!"
So the "stretch" mode on the DVX is actually a DSP effect, and not just sampling of the 16:9 area of the CCD.
The DVX's take the 4:3 signal ("720x576") and then post process the 16:9 out of it then? Explains the drop in resolution.
So any signal sampled off the CCDs (regardless of it's shape) can be considered 'native' then. Just like working with film where you can crop any 'native' resolution out of the 35mm area when digitizing for post. Of course you have to be reasonable with the physical chip resolution.
I always find "stretch" misleading, as the actual linear signal (like composite video) doesn't have an aspect ratio, and it's only stretched on an incorrect display. (I can't tell aspect ratio from my scopes).
I guess in this sence they are refering to taking that 4:3 signal and virtually 'streatching it in post' in the camera to get 16:9. - Ok, NOW that makes sence. Yeah, shoot 4:3 and stretch in post folks.
- Mikko ... feeling paticularly educated tonight.
So the "stretch" mode on the DVX is actually a DSP effect, and not just sampling of the 16:9 area of the CCD.
The DVX's take the 4:3 signal ("720x576") and then post process the 16:9 out of it then? Explains the drop in resolution.
So any signal sampled off the CCDs (regardless of it's shape) can be considered 'native' then. Just like working with film where you can crop any 'native' resolution out of the 35mm area when digitizing for post. Of course you have to be reasonable with the physical chip resolution.
I always find "stretch" misleading, as the actual linear signal (like composite video) doesn't have an aspect ratio, and it's only stretched on an incorrect display. (I can't tell aspect ratio from my scopes).
I guess in this sence they are refering to taking that 4:3 signal and virtually 'streatching it in post' in the camera to get 16:9. - Ok, NOW that makes sence. Yeah, shoot 4:3 and stretch in post folks.
- Mikko ... feeling paticularly educated tonight.
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