Uncompressed output discussion at DVinfo.net

Mike Medavoy · November 27th, 2005, 01:07 PM

Hey,

There is a lot of discussion on the Canon XH1 forum about the HD-SDI output on that camera, ways of capturing through that port, possible usus of that feature etc.

How about the component output on "our" camera, the HVX200 :-)

Ways of capturing uncompressed HD... advantages/disadvantages... specs of the uncompressed stream... potential uses of this output... or impracticabilities (does this word exist) etc

Do people find this output useful on the HVX200?

Graeme Nattress · November 27th, 2005, 02:19 PM

Component output capture or SDI capture for that matter is only really practical in a studio setting, especially if you wish to capture uncompressed. It can produce quality advantages, but also increases the power of the computer and hard drives you need to edit to maintain that advantage, and the deck needed to master to.

Graeme

Frederic Segard · November 27th, 2005, 03:47 PM

If you do stick to studio work, a computer with sufficient power, hard drive space and speed is not really that out of reach anymore. Doing green screen work will always yield better results. Of course, 4:2:2 is better then 4:1:1, but when you have 4:4:4 for keying... well lets just say there is no comparison.

The only question I would ask myself is, how much of a quality hit you get from the analog out of the HVX vs. if the HVX would have had straight HD-SDI out? Since there is a double conversion going on from the camcorder's analog output to the digitizing on the computer...

Graeme Nattress · November 27th, 2005, 04:35 PM

You'd need a pretty serious camera to get 4:4:4 though, and certainly not over componet - dual link HD SDI is needed for that! Personally, I feel that lack of compression is the bigger benefit to keying that chroma space, green being mostly luma anyway.

Graeme

Keith Wakeham · November 28th, 2005, 03:57 PM

Component offers some problems as well as advantages. In a perfect world / awesome cool lab setting the DAC doesn't have any slew and your ADC doesn't either. In the real world it does and this causes slight voltages lags that throw off your ADC just a little more. So if the electronics between the port of the camera to the device are really top quality and introduce little noise you should in theory achieve close to HD-SDI, but will always be a little off. Correlated Double sampling is a good way to deal with the slight lag since it takes two measures.

Their are currently component to HD-SDI and the Wafian has component I think. Which are currently the only available option.

Also analog has a colour space of 4:2:2 normally. The Cb and Cr are normally run at 1/2 the clock of the Y but you can sample twice as much for 4:4:4 but you will likely not gain much.

Its unknown what the HVX DAC is starting with. Are they outputing 8 bit or more. I would guess 8 but you can always sample higher which when dealing with analog isn't a bad idea.

November 27th, 2005, 01:07 PM	#1
Mike Medavoy Regular Crew Join Date: Sep 2005 Posts: 63	Uncompressed output discussion Hey, There is a lot of discussion on the Canon XH1 forum about the HD-SDI output on that camera, ways of capturing through that port, possible usus of that feature etc. How about the component output on "our" camera, the HVX200 :-) Ways of capturing uncompressed HD... advantages/disadvantages... specs of the uncompressed stream... potential uses of this output... or impracticabilities (does this word exist) etc Do people find this output useful on the HVX200?

November 27th, 2005, 02:19 PM	#2
Graeme Nattress RED Problem Solver Join Date: Sep 2003 Location: Ottawa, Canada Posts: 1,365	Component output capture or SDI capture for that matter is only really practical in a studio setting, especially if you wish to capture uncompressed. It can produce quality advantages, but also increases the power of the computer and hard drives you need to edit to maintain that advantage, and the deck needed to master to. Graeme __________________ www.nattress.com - filters for FCP

November 27th, 2005, 04:35 PM	#4
Graeme Nattress RED Problem Solver Join Date: Sep 2003 Location: Ottawa, Canada Posts: 1,365	You'd need a pretty serious camera to get 4:4:4 though, and certainly not over componet - dual link HD SDI is needed for that! Personally, I feel that lack of compression is the bigger benefit to keying that chroma space, green being mostly luma anyway. Graeme __________________ www.nattress.com - filters for FCP

November 28th, 2005, 03:57 PM	#5
Keith Wakeham Major Player Join Date: Jan 2005 Location: St. John's, NL, Canada Posts: 416	Component offers some problems as well as advantages. In a perfect world / awesome cool lab setting the DAC doesn't have any slew and your ADC doesn't either. In the real world it does and this causes slight voltages lags that throw off your ADC just a little more. So if the electronics between the port of the camera to the device are really top quality and introduce little noise you should in theory achieve close to HD-SDI, but will always be a little off. Correlated Double sampling is a good way to deal with the slight lag since it takes two measures. Their are currently component to HD-SDI and the Wafian has component I think. Which are currently the only available option. Also analog has a colour space of 4:2:2 normally. The Cb and Cr are normally run at 1/2 the clock of the Y but you can sample twice as much for 4:4:4 but you will likely not gain much. Its unknown what the HVX DAC is starting with. Are they outputing 8 bit or more. I would guess 8 but you can always sample higher which when dealing with analog isn't a bad idea. __________________ www.engr.mun.ca/~wakeham/index.htm

November 27th, 2005, 03:47 PM	#3
Frederic Segard Major Player Join Date: Jul 2003 Location: Montreal, Canada Posts: 209	If you do stick to studio work, a computer with sufficient power, hard drive space and speed is not really that out of reach anymore. Doing green screen work will always yield better results. Of course, 4:2:2 is better then 4:1:1, but when you have 4:4:4 for keying... well lets just say there is no comparison. The only question I would ask myself is, how much of a quality hit you get from the analog out of the HVX vs. if the HVX would have had straight HD-SDI out? Since there is a double conversion going on from the camcorder's analog output to the digitizing on the computer...