Colour banding after export with XAVC S-I 4K, 4:2:2 10 bit?

New Here ,
Mar 09, 2021 Mar 09, 2021

Copy link to clipboard

Copied

I hope someone can help.

 

I'm trying to get my head around why my exported project on Premier Pro is showing colour banding when there is none during playback. I'm using HAVC S-I 4K, 4:2:2 10 bit recorded on the Sony A7S III. I'm recording S-Log 3, with colour mode S-Gamut3. I have tried adding 1% noise, I am exporting at 240mbps bit rate, maximum render quality. Any advice would be greatly appreciated.

TOPICS
Editing, Error or problem, Export

Views

244

Likes

translate

Translate

Translate

Report

Report
Community Guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more
community guidelines
Enthusiast ,
Mar 09, 2021 Mar 09, 2021

Copy link to clipboard

Copied

Likes

translate

Translate

Translate

Report

Report
Community Guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more
community guidelines
New Here ,
Mar 09, 2021 Mar 09, 2021

Copy link to clipboard

Copied

Thank you, I am now trying to mess around with this. Is there any way of doing it on a H.264 export format? Or would I need to follow this work around and then convert to H.264? 

Likes

translate

Translate

Translate

Report

Report
Community Guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more
community guidelines
Enthusiast ,
Mar 09, 2021 Mar 09, 2021

Copy link to clipboard

Copied

I don't have definitive answer to your specific issue, but here is steps that seems logical:

1) Try to render/export with enabled 'Maximum Bit Depth' in sequence settings

2) If not help - transcode the sources into Prores 422 or 10bit DNxHR

Likes

translate

Translate

Translate

Report

Report
Community Guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more
community guidelines
Adobe Community Professional ,
Mar 09, 2021 Mar 09, 2021

Copy link to clipboard

Copied

I'm going into the details here not because you may need it all, but because many of the people seeking help here aren't that experienced, work with that cam, and have similar issues. So giving an in-depth response that will help even the newbies is useful over time here.

 

Any HEVC encoded file, even in "10bit" and supposedly 422, throws out a TON of data from the original images. It's how it's designed to work, how it compresses the image. One expert's explanation example was something like it takes a block of similar pixels, and if you've got four pixels that are 233/241/242, and another of that block is232/241/242, that will get "rounded" and stored as the other three pixels.

 

So in the encoding of the file in the camera, though it's still technically a 10-bit file, it's missing a lot of actual needed data to be able to fully utilize the 10 bits in say color grading. You don't have near the ability to move image data around in grading that you would if it was say a RAW or ProRes file.

 

I work with colorists daily, and this is an issue they constantly have to work with their clients about. HEVC 10-bit files are not the equivalent of 10-bit RAW files. They're better than an HEVC 8 bit file true. But not the full match to a RAW or ProRes or similar file.

 

What this can mean at times is noticeable generational loss in fine details and smooth gradations. Um ... gee, like banding. Hair. Yea.

 

So you can't do very much to the media much of the time other than 'stretch' it back to a "normal" Rec.709 file contrast/saturation. And you need to be careful how you grade ... use small increments of mulitple tools to do say a brightening, rather than one tool for the job. You'll get a better chance of avoiding artifacts/banding.

 

And for exports, not all codecs work as well as others. Going back to a long-GOP format at export can trigger banding, again because of the rounding native to that format noted above. Sometimes staying in Cineform, DNxHD/R or ProRes keeps it looking mostly sort of not banded.

 

If you've got a full-on GPU in your rig, Max Depth (unless exporting to DNxHD/R in 4444) is not normally needed, as with that GPU that is what PrPro will do. Sometimes it actually causes issues, so I leave it of. You need to test both ways when you're on the edge like this, though.

 

Max Render Q is all about resizing, period. It's for when you are doing major resizing like a 4k clip in a 1080 sequence, and you are getting jaggies on diagonal lines. Otherwise, leave it off as it can also at odd times cause artifacts.

 

And a last section, as some of the colorists I work with get fed A7S III files shot in log and I've seen their discussions on how to handle that media.

 

Be very, very precise on your in-camera exposure. If you are slightly over or under, not even to the point it looks bad at first, and then grade the file, woa ... banding banding banding.

 

Also, another proper colorist's step: apply the corrective LUT or work to normalize the image to Rec.709 in Premiere, but then go before the LUT to do your basic trim work, exposure/white point/saturation/contrast.

 

So this could be done by applying the normalization LUT in the Creative tab's dropdown list, then using Basic tab to adjust the image to "normal" looking as then the controls you are applying are processed before the LUT as colorist's are taught to do.

 

Or use two instances of Lumetri ... apply the corrective LUT or steps in the second one, then go to the first and do the adjustment of exposure/white point/contrast/saturation.

 

And of course, after it's 'normalized', do any other shot-matching or "look" work.

 

Neil

Likes

translate

Translate

Translate

Report

Report
Community Guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more
community guidelines
New Here ,
Mar 09, 2021 Mar 09, 2021

Copy link to clipboard

Copied

Neil, thank you so much for this. I am currently trying to export it with minimal editing, just the SGamut3.Cine/Slog-3 to 709 look up table preset, and some slight brightness adjustments (using exposure, white points and black points) to see how that comes out. I left maximum render depth off, and I'm trying to export in H.264. If that doesn't work I will export in DNxHD and try to encode it from there. I will reshoot some footage with precise exposure tomorrow and try to play around with that as well. 

I really appreciate the help I've been driving myself crazy looking down the internet rabbit hole for solutions. 

Likes

translate

Translate

Translate

Report

Report
Community Guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more
community guidelines
Adobe Community Professional ,
Mar 09, 2021 Mar 09, 2021

Copy link to clipboard

Copied

Hey, these kinds of things drive you nuts, right?

 

I got a GH3 when they first came out, as the All-Intra (intraframe) setting was at a Mbps that was pretty amazing for a cam that cheap and small. But that had a lot more noise in the shadows than the  non-All-Intra MOV/mp4 files it made. So like many, I struggled using the mov/mp4 format/codecs out.

 

Finally ... I realized that ok, you have to use Neat DeNoiser on the files, but the All-Intra did deliver a ton more data in the shadows and highlights, and could be graded a lot further. Which is to say, could take some grading without banding and artifacts. It's a ... "thicker" file of data? Something like that.

 

Every cam has it's little things you need to figure out.

 

Neil

 

 

Likes

translate

Translate

Translate

Report

Report
Community Guidelines
Be kind and respectful, give credit to the original source of content, and search for duplicates before posting. Learn more
community guidelines