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Old March 17th, 2011, 01:44 AM   #1
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Interlace Banding

I just burnt by first Blu-ray disc from within Vegas and I'm noticing banding on the edges of saturated colors. (think red fabric against a black background). I set project properties to "upper field first" and "blend fields". If I render as a progressive mpeg 2 file and view it on my computer monitor there are no artifacts. If I burn this file to Blu-ray within DVDA, the artifacts come back. This only seems to be a problem with fairly bright colors. All of my footage was shot at 30p on an EX1. It's nto a huge issue, but I'd like to get rid of it if possible.

Thanks.
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Old March 18th, 2011, 03:41 AM   #2
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Re: Interlace Banding

I don't know much about this, but 30p is a poor choice for DVD but is perfect for computer viewing. Also, you are taking 30p footage and interlacing, it sounds like, which is not going to provide good results.

I would suggest for future if you can shoot in mode closer to your output you would be better off.

Consider taking original footage and encode with tmpgenc, or HD link, then edit it. Long story short, the conversion process you're using is not working out, and your original footage is a good way off from what it needs to be for DVD
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Old March 18th, 2011, 04:42 AM   #3
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Re: Interlace Banding

Quote:
Originally Posted by Craig Kovatch View Post
I set project properties to "upper field first" and "blend fields".
If that gives you artifacts, try "lower field first" and see if that solves the problem. I am not sure whether you should choose "blend fields" at all: If your original is progressive, what is there to blend? But I do not have any experience with 30p, I shoot 24p, and that is what I would use on a BD.

The point is, try different settings and see what works.

EDIT: Oh, wait, I just loaded DVD Architect and see the choices it gives you in the BD frame rate do not ask the field order. So, is this the Vegas project properties you are talking about? If so and if you are using 30p footage, set the properties to 30p and let the DVDA figure out how to interlace it.
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Old March 20th, 2011, 12:08 AM   #4
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Re: Interlace Banding

I actually burnt the Blu-ray disc right from within Vegas. I read somewhere that 30p isn't in the Blu-Ray spec, so I'm guessing Vegas (and probably DVDA) interlaces the signal to 60i before burning it. The project I shot was a figure skating event, and I was worried about the judder from shooting in 24p, especially with the constant panning involved. I just checked DVDA and there are no options for 30p, just 29.97i (i'm talking about BD not DVD). Do you really shoot everything in 24?
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Old March 20th, 2011, 01:08 AM   #5
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Re: Interlace Banding

After some research, I found something on dvxuser.com:



"Yes, in 4:2:0 interlaced images, vertical resolution of the chroma is roughly halved since the chroma samples effectively describe an area 2 samples wide by 4 samples tall instead of 2X2. In addition, the spatial displacement between both fields can result in the appearance of comb-like chroma artifacts.
As is the case in the 30p to 60i conversion, this effectively cuts the chroma resolution in the vertical plane by half. Noticeable on some material, but not all. The more intense the primary colors and the sharper the edges of those colors, the more likely it will make a visible difference. From across a room though, it would be insignificant to the average viewer."

Looks like in the future I'll have to shoot in either 24p or 60i.

Thanks again.
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Old March 20th, 2011, 01:18 AM   #6
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Re: Interlace Banding

Quote:
Originally Posted by Craig Kovatch View Post
Do you really shoot everything in 24?
Yes, I do (well, in 24/1.001 since my EX-3 does not support true 24). For about a century 24 fps has been the standard of film making. 24p, whether the true 24p or the more common 24/1.001, can be easily converted to 25p, 50i and 60i. The opposite is not true.

Though, I do not shoot figure skating. If I ever did and was fairly certain there was little chance of it ending up on film (in other words, strictly for video), I would probably make an exception and shoot in 60i because those skaters sometimes make very fast moves which interlaced video can capture better than progressive. But as a proverb in my home country says, exceptions affirm the rules. And my personal rule is 24p.
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Old March 20th, 2011, 02:31 PM   #7
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Re: Interlace Banding

Render using "interpolate" instead of "blend", particularly for video with lots of motion. I use "interpolate" exclusively.
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