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rendering problems

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Greg FitzPatrick
rendering problems
on Mar 14, 2015 at 5:52:03 pm

Here is a snapshot from a clip shot with sony avc



Here is the bleached out look I wanted using the Sony brightness & contrast VEFX



Here is what MainConcept and Sony AVC renderings came out as



Here is what I got from a Quicktime render of the same clip. It is for all purposes identical to the filtered original.



Anybody have a clue as to why this is happening?

I am using VP12


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Aaron Star
Re: rendering problems
on Mar 14, 2015 at 10:56:16 pm
Last Edited By Aaron Star on Mar 14, 2015 at 11:26:23 pm

Looks to me like Sony and MC have more latitude, and the quicktime is either expanding the level range out so the background is clipping or is not including the levels above a certain level. I was able to recreate what you have using your original with Sony AVC. Use your video scopes and make sure that background is clipping, or use a white background when you shoot. That way the white will roll off faster than the skin tones.



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Greg FitzPatrick
Re: rendering problems
on Mar 15, 2015 at 12:05:26 am

Thanks for responding, Aaron.

My background is intentionally a green screen. When I decided to do the bleaching and saw that the results looked good in my preview window I didn't bother to key out the green.

As I understand it Sony XAVC is recommended for prerendering and I find it odd that it can't handle the filter settings Brightness 0,260 contrast 0,279, contrast center 0,500. A render of the unfiltered clip looks fine.

I also tried rendering with Sony AVC and MainConcept AVC and both resulted in similar results as XAVC. Can you tell me how you were able to recreate/render the washed out filtered image with Sony AVC?

Can you take my green-screened image and filter it with the settings I list above and then get a render that matches the preview with XAVC? I can't do this.


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Aaron Star
Re: rendering problems
on Mar 15, 2015 at 1:22:21 am

Here is a zip of the project settings. It does not render any different between SonyAVC, XAVC, or QT. The main thing is get the green high enough to clip out. Its easier to send you the vegas file than document the settings.

blown-out-test.zip


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Greg FitzPatrick
Re: rendering problems
on Mar 15, 2015 at 10:34:48 am

Thanks again. Aaron.

I loaded your VEG and verified that you could recreate the washed out effect with out using the Video Event FX Brightness & Contrast and render it faithfully with SonyAVC, XAVC, or QT.

But then I also noticed that I could do the bleaching with the Brightness & Contrast filter and get it to render just as faithfully in all three as well.

Since I couldn't do that in my VEG I realized there must be something different with our project settings. There was: You were using the 8 bit pixel format and I had been using the 32-bit floating point (video levels)

When I switched to 8 bit the render came out bleached and identical to the filtered original without any of the green background breaking through.

When I switched back to 32-bit floating point (video levels) and the washed out effect looked the way I wanted it to in my preview, the SonyAVC and XAVC renders caused the green background to breakthrough while the QT render kept it suppressed i.e. the QT results were faithful to my preview screen.

Using your method for washing out the image and rendering with 32-bit floating point (video levels) the green also breaks through (where your mask doesn't cover it) with SonyAVC and XAVC -- but the QT render with Sorenson Video 3 suppresses it.

Since I am quite a ways into my project using 32-bit floating point (video levels) I don't see switching to the 8 bit pixel format for the entire production, but I do realize that I will need to do 8 bit pre-renders on all my 'bleached' clips that have greenscreen backgrounds. A little extra work, but a lot simpler than chromakeying and masking a moving target against an uneven greenscreen.


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Aaron Star
Re: rendering problems
on Mar 15, 2015 at 6:49:53 pm

I see what you are saying now. Yeah 32-bit mode is going to have more levels of brightness and color info. You should be able to do the same thing, just need to keep working it until the green level are clipping the way they do in 8-bit mode. I tried the same thing using a mask, and uploaded another version of the file. See if this works better. You can play with the levels on the mask to vary the detail levels in the hair and skin. As far as the green spill on the hair goes, I am not sure how to get rid of that, minus dropping the color.

Blown-out-test-2.zip


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Greg FitzPatrick
Re: rendering problems
on Mar 15, 2015 at 10:29:03 pm

Masking was a good way to go. And using only Brightness and contrast with a mask on top kept the green away in the 32 bit render.

How do you feather the Mask Generator mask?

Too bad I can't see the results before hand in my preview device. Tried switching between computer rbg and studio rbg but it didn't seem to help.

By the way, is there a way to eliminate audio in the XAVC render?


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