Banding after FCPX Export

Hi all

First time post and looking forward to being involved with the forum.

I'm having an issue with XAVC footage in FCPX. This is the first time I have natively edited XAVC footage in FCPX. I usually work off ProRes proxies but for this particular job I did not. I have a completed edit in FCPX and I go to export a ProResHQ through SHARE > MASTER FILE. Export goes fine but when I look at the exported video it has quite a lot of banding on the first 'fade up' of the video and also a lot on the final graphic at the end. The graphic at the end is a transparent layer with a colourful shot of a dress underneath and a graphic over the top of it all.

Has anyone else experienced some banding issue with editing native XAVC footage in FCPX? The XAVC footage has been rewrapped (not optimised) during FCPX's import stage so its still a 10-bit codec. I even exported to a ProRes4444 (which is a 12-bit codec to my knowledge?) and it still had banding though it wasn't as bad. Regardless, I shouldn't being seeing it with a ProResHQ export.

Cheers

Anybody?

I don't think the banding is a result of the XAVC footage, but you might tell us what flavor of XAVC you are using. We shoot XAVC-I and XAVC-L and the footage itself always looks clean. The banding may be more related to any underlying graphics or compositing and also may be due to the effect you are using to fade in and out. Are you using a standard FCPX dissolve or some other transition? What happens if you replace (as a test) the XAVC footage with another piece of footage having a different source codec? Maybe also try replacing the footage with a solid background to test if the banding is still present. I believe most NLE's sometimes struggle with banding issues in general under certain circumstances.

This particular footage is XAVC-I from my F55. Yes just the standard FCPX dissolve. Just tried replacing the footage with two different clips and applying a fade up. The original XAVC clip is a shot of the sun rising over the beach. The first clip I replaced the original clip with was a ProRes LT and after applying the fade up, then exporting to a ProResHQ it showed no signs of banding on the export clip. The second clip was a ProRes Proxy shot with the sun rising over some trees. Again I applied the fade up, exported to ProResHQ and it showed no signs of banding.

The reason I mention the original XAVC clip being the sun rising over the beach is because its probably a shot with a lot of 'shades of grey' especially after throwing a dissolve up over it. The banding looks a lot like an image after some heavy noise reduction. I've seen this happen on a similar sunset scene where I tried to use NR on it before.

I've thrown the video up on Vimeo if you wanted to see what I was talking about: vimeo.com/138951457

Its the first fade up shot. If you pause halfway through it you will see what I'm talking about. I know its been compressed by Vimeo but it still is a good indication of what I'm seeing in my master export. It happens on the graphic at the end as well. On closer inspection I think I can see slight banding happening in the sky throughout the video. Might be harder to see on the Vimeo version...

Cheers

Nice video, by the way. I do see a lot of banding throughout, and particularly in the initial fade up, the blue sky and the gradient background at the end. I'm not sure I can offer a sound reason why you are getting this, but I have noticed similar banding in certain projects with FCPX before (on footage other than XAVC-I). Gradients seem to be the most problematic but I have also seen banding with dissolves as you are seeing.

Hopefully others can offer some suggestions. I am not convinced it is a problem with FCPX exclusively, but possibly with Mac AV Foundation as Quicktime 7 seems to render gradients more smoothly. You might try encoding a QT7 movie from your master file and see if there is any difference.

Hi Gavin,

Did you record your XAVC-I footage in any form of S-Log? And if so, how dit you grade it? Did you use a LUT prior to your grade?
I made a small test this morning before rushing of to the IBC and loaded a shot in FCPX from my F5. It was recorded in SLog3.Gamut3.Cine.
If I did NOT apply the LUT I normally use on this kind of footage (I like the Arri-LogC LUT and use this one either from within the info tab in the inspector, or I use it from within Color Finale) andjust graded the footage using only the controls in the Color Board, I noticed banding to occur when I applied a fade from black and rendered the fade.
However, this didn't happen when I applied the LUT first and then graded to taste using the Color Board and applying and rendering the fade.
I know that applying a 1D camera LUT is essential for converting the SLog footage in a proper way to the Rec709 Gamma Curve and colorspace.

Thanks Dan for your help anyways

Hi Robbert

For this shoot I did shoot Slog3.SGamut3.Cine but I did 'burn in' a LUT in camera so the final image coming into the edit is not LOG footage. Just standard Rec709. I should mention that this LUT I used in a modified version of Sony's 'LC709TypeA' LUT. It basically takes the original Sony LUT and brings the slightly lifted blacks back down to 0% and extends the highlight range up to 109%. So the original LC709TypeA LUT range is 4%-100% and the modified LUT takes it into extended range with levels 0%-109%. I'm starting to wonder if this 'stretching' of the range is causing this.

I never have this issue when I shoot SLog and do an offline to online with Resolve and I use the LC709 LUTs from Sony quite a lot. But then I'm using the original LUTs and not a modified one like this instance...

Can it be the 120fps ?

Hmmmm I'd be very surprised if it was. Saying that I don't usually shoot specifically at 120fps. Usually 150-180fps when doing slow motion. To my knowledge theres not anything different with the codec at high frame rates. Still XAVC-I 10-bit 422. The only thing the camera does different is pixel binning but that shouldn't affect things like banding...

Still, since I haven't shot lots specifically at 120fps before I can't rule it out without further testing...

Hi Gavin.

I'm on a shoot with the F5 this week and when I can find a moment to squeeze in a test with your HFR settings with a baked in LUT, I will let you know. Can you send me the LUT you used? You can use my PM: rjvddoes at mac dot com