XLH1 Video Quality Issue

David Walding · August 19th, 2006, 01:18 PM

I have been very happy with it, but I have noticed that in RAW and compresed video I get oscillating light fluctuations in shiny areas of glasses, or the chrome in chairs, etc. with movement. Is this what some call artifact? It could be my amatuer inabilities but what can be done? Is there a production effect to add to remove it? I am shooting in 30 fps in AV Mode.

Pete Bauer · August 19th, 2006, 04:51 PM

That's not typical compression artifact, but not sure what it actually is. If shooting Tv under some artifical lights (eg halogen or mercury vapor, as noted on p72 of the user manual...and I've seen that happen), you can get an effect like that. But in Av, I don't know; haven't seen it in that mode and not mentioned in the manual. Do you have a sample clip you can post to make sure we're talking about the same thing?

David Walding · August 22nd, 2006, 08:36 AM

Here ya go. This is not the best example but note that the problem is worse on larger reflective items. MPG encoding covers up the small stuff.

Barry Goyette · August 22nd, 2006, 07:46 PM

Hi David

I'm not sure I'm seeing much of anything, other than a little aliasing. It's difficult to tell as it is so short, and has little movement, but I'm guessing that you are simply seeing line "twitter" (aliasing) which is a normal component of DV quality video image. If you have a clip that shows the problem more obviously, it would help.

Barry

A. J. deLange · August 23rd, 2006, 11:16 AM

Classic aliasing.

David Walding · September 3rd, 2006, 01:07 PM

Can anything be done to help prevent it? This means I cant use the XLH1 for TV Quality commercials.

Richard Hunter · September 3rd, 2006, 07:38 PM

Hi David. This is a common problem on my XL2 as well. Basically, the lens is able to resolve finer details than the SD resolution CCD can capture without aliasing occurring. Ideally, there would have been a low pass filter before the A/D conversion of the CCD output to prevent this but it's not an ideal world. :)

On my XL2, I find that the Century Optics 0.7X converter softens the image just enough to largely avoid this aliasing problem.

If your commercial can take something like a classis soft filter, it might be worth trying in order to reduce the sharpness. The camera has a sharpness adjustment built-in, but it's probably done digitally i.e. after the A/D conversion so doesn't help the aliasing much.

Richard

A. J. deLange · September 4th, 2006, 06:26 AM

I believe the XL-H1 does have some anti aliasing filtering built in because the aliasing is much, much less pronounced than with preveious XL cameras. Aliasing can often be dealt with simply by changing the position/angle of the camera so try a slightly different composition.

August 19th, 2006, 01:18 PM	#1
David Walding Regular Crew Join Date: Aug 2003 Location: Claremore Ok Posts: 44	XLH1 Video Quality Issue - SD I have been very happy with it, but I have noticed that in RAW and compresed video I get oscillating light fluctuations in shiny areas of glasses, or the chrome in chairs, etc. with movement. Is this what some call artifact? It could be my amatuer inabilities but what can be done? Is there a production effect to add to remove it? I am shooting in 30 fps in AV Mode.

August 19th, 2006, 04:51 PM	#2
Pete Bauer Wrangler Join Date: May 2003 Location: Eagle River, AK Posts: 4,100	That's not typical compression artifact, but not sure what it actually is. If shooting Tv under some artifical lights (eg halogen or mercury vapor, as noted on p72 of the user manual...and I've seen that happen), you can get an effect like that. But in Av, I don't know; haven't seen it in that mode and not mentioned in the manual. Do you have a sample clip you can post to make sure we're talking about the same thing? __________________ Pete Bauer The most beautiful thing we can experience is the mysterious. It is the source of all true art and science. Albert Einstein Trying to solve a DV mystery? You may find the answer behind the SEARCH function ... or be able to join a discussion already in progress!

August 22nd, 2006, 07:46 PM	#4
Barry Goyette Trustee Join Date: Oct 2001 Location: San Luis Obispo CA Posts: 1,195	Hi David I'm not sure I'm seeing much of anything, other than a little aliasing. It's difficult to tell as it is so short, and has little movement, but I'm guessing that you are simply seeing line "twitter" (aliasing) which is a normal component of DV quality video image. If you have a clip that shows the problem more obviously, it would help. Barry

August 23rd, 2006, 11:16 AM	#5
A. J. deLange Major Player Join Date: Jun 2004 Location: McLean, VA United States Posts: 749	Classic aliasing.

September 3rd, 2006, 01:07 PM	#6
David Walding Regular Crew Join Date: Aug 2003 Location: Claremore Ok Posts: 44	Can anything be done to help prevent it? This means I cant use the XLH1 for TV Quality commercials.

September 3rd, 2006, 07:38 PM	#7
Richard Hunter Trustee Join Date: Dec 2004 Location: Lipa City Batangas, Philippines Posts: 1,110	Hi David. This is a common problem on my XL2 as well. Basically, the lens is able to resolve finer details than the SD resolution CCD can capture without aliasing occurring. Ideally, there would have been a low pass filter before the A/D conversion of the CCD output to prevent this but it's not an ideal world. :) On my XL2, I find that the Century Optics 0.7X converter softens the image just enough to largely avoid this aliasing problem. If your commercial can take something like a classis soft filter, it might be worth trying in order to reduce the sharpness. The camera has a sharpness adjustment built-in, but it's probably done digitally i.e. after the A/D conversion so doesn't help the aliasing much. Richard

September 4th, 2006, 06:26 AM	#8
A. J. deLange Major Player Join Date: Jun 2004 Location: McLean, VA United States Posts: 749	I believe the XL-H1 does have some anti aliasing filtering built in because the aliasing is much, much less pronounced than with preveious XL cameras. Aliasing can often be dealt with simply by changing the position/angle of the camera so try a slightly different composition.