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Kona output banding / hatching in illegal whites & colours

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editmonkey
Kona output banding / hatching in illegal whites & colours
on Mar 27, 2007 at 10:58:24 am

Hello.

FCP 5.1.2
Kona 3 ver 3.3

I have a problem with a DV FCP project. The footage is mostly DV codec, and some of it was shot very hot. In these shots they look fine in the timeline, but when I render them in the timeline I get a tartan like hatching of grey shapes in the whites. Looking at the scope these whites are illegal, but when FCP renders is 'on the fly' they look fine.

The sequence render settings are - and need to be - High Precision YUV, with super whites enabled. When you change the scene's render settings to render in 8 bit then this issue goes away. Apparently this has happened on the FCP video output of the GUI flatscreen monitor as well, though I have not seen it. It seems to be just the Kona which is amplifying the problem.

Has anyone seen this before?

Thanks,
Tom.


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JeremyG
Re: Kona output banding / hatching in illegal whites & colours
on Mar 27, 2007 at 1:53:10 pm

Is the video scaled at all?


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editmonkey
Re: Kona output banding / hatching in illegal whites & colours
on Mar 27, 2007 at 2:08:33 pm

Not scaled, or at least not intentionally. The stuff came in DV. But we are seeing the same thing with digibeta ingested 10bit uncompressed straight into FCP through the Kona 3. When you grade it up and push it illegal, this banding and hatching occurs. If it is any consolation you can see something similar in the FCP GUI, but not nearly as bad. Is this a limitation / known issue of working YUV high precision?

Out of interest does the Kona scale on input and output? I guess it does not if it lets you output illegal colours.

Cheers,
Tom.


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JeremyG
Re: Kona output banding / hatching in illegal whites & colours
on Mar 27, 2007 at 4:12:08 pm

I was having this same exact problem with HD material that had been scaled over 100% in the motion tab. I had to bring the highlight levels way below where I normally would. After chatting with AJA for a while, they suggested adding a desaturation filter and leave the level @ 0 (which basically does nothing to your image). That forces another level of rendering and the problem goes away, at least it did for me. I see this only on 10 bit sequences, just like you.

Try the desaturation filter and rerender and see if that works for you.


Jeremy


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christopherkarcher
Re: Kona output banding / hatching in illegal whites & colours
on Mar 27, 2007 at 9:27:10 pm

This has been an ongoing problem for us as well. We did a series of political spots a few months back in 10 BPC 29.97 SD and and any red typography created in FCP and AE (even if it was NTSC legal) was terribly aliased on the edges- all of our settings were correct in FCP/AE (prefs update)but something was happening in the FCP timeline with the footage.

I wish AJA and apple could find and resolve the issue- our only recourse was to render everything in the RGB codec and it seemed to fix most of the issue- however that mean't getting the entire spot in After Effects for a render... or our footage would shift colors/levels! Arrgghh!



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editmonkey
Re: Kona output banding / hatching in illegal whites & colours
on Mar 27, 2007 at 10:44:56 pm

Thanks Jeremy & Christopher.

So it sounds like this is a 'known issue' then. Shouldn't AJA be telling us about it? And yes, rendering everything in RGB does seem to fix it, but that's an awful lot of processing. Which, as you say, is gonna shift things a little too much for my liking.

Interestingly the pattern that I see in a blown out white square is like a tartan quilt pattern of grey. And if you turn on 'show excess luma' in FCP then the same pattern is shown in the zebra. Does this mean that AJA are blaming Apple maybe? I would like to know. Anyway surely the thing should just hard clip the image, not produce funky patterns over the top. To be fair it is a seriously illegal picture, going up to about 0.76volts. But like I say it should surely just hard clip.

I reckon this is one I will take up with AJA. Cheers for your wisdom though guys,
Tom.


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walter biscardi
Re: Kona output banding / hatching in illegal whites & colours
on Mar 27, 2007 at 10:55:34 pm

[editmonkey] "So it sounds like this is a 'known issue' then. Shouldn't AJA be telling us about it? And yes, rendering everything in RGB does seem to fix it, but that's an awful lot of processing. Which, as you say, is gonna shift things a little too much for my liking."

FCP has been having a lot of issues with 10bit rendering lately. I'm pretty certain Apple's FCP 5.1.4 was supposed to have addressed this issue. I see you're still running FCP 5.1.2. We're going to update to 5.1.4 tomorrow.

Walter Biscardi, Jr.
http://www.biscardicreative.com
HD Editorial & Animation for Food Network's "Good Eats"
HD Editorial for "Assignment Earth"

Read my blog! http://blogs.creativecow.net/WalterBiscardi


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JeremyG
Re: Kona output banding / hatching in illegal whites & colours
on Mar 27, 2007 at 11:27:09 pm

I see the exact pattern.

It was explained to me as an FCP problem as it has to do with a real time render from interlaced YUV to RGB progressive for display. Rendering is controlled by FCP and not AJA. I wanted to think it was an AJA problem as well because it only happened on my external display and the problem didn't show up in the viewer, canvas or any exported quicktime movies. Calling AJA will certainly help as they are closer to Apple then you or I am, that's for sure. They will be able to remind apple to fix this nice little 'feature'. It's definitely only a 10 but problem and happens in illegal whites, but my initial whites weren't over exposed so it happens in legal whites too.

And Walter, I have not updated to 5.1.4 citing fear of the unknown.

Seems to be working alright on some people's machines, but there's too much going on for me to take the risk. editmonkey, if you end up upgrading to 5.1.4 and that fixes it, please let me know. I have a spot to master next week and saving the hassle to put the desaturation filter on all my clips will help a lot.

Jeremy


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christopherkarcher
Re: Kona output banding / hatching in illegal whites & colours
on Mar 29, 2007 at 2:31:23 pm

we may be the first to try. The same political group is coming back for a new spot (round 2) next week. They just finished shooting this morning. I'll let you all know what happens.



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Kevin Wild
Re: Kona output banding / hatching in illegal whites & colours
on Mar 30, 2007 at 4:43:16 am

We had a similar problem with video jumping around only when rendered. If I made the clip unrendered and played it, it was fine.

Very strange stuff. I'll work around it since a new version is on it's way hopefully in a few weeks.

KW


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Kevin Wild
Re: Kona output banding / hatching in illegal whites & colours
on Mar 30, 2007 at 4:44:12 am

I should've said "when video whites were illegal" the picture jumped around. If I put a broadcast safe on it, it was fine.


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