strong banding in fade (generated media )

Mindmatter wrote on 2/4/2016, 8:18 AM

Hi all,

working on a test project with footage from my A7S, I created 2 simple fades: a pan towards the sun merging into a solid white media color then fading to black. The footage has a vignette FX on it made with the soft contrast plugin.
You first see strong banding around the vignette, then the fade to black also divides into several gray bands.
I first thought it was because the project was set to 8 bit, but setting it to 32bit floating didn't help.
Here's a file with the fades:

https://www.dropbox.com/s/qlwkhym5v6o3knb/A7S-test.mp4?dl=0

I should mention that the banding is only in the renders, I tried different kind of AVC renders, this one is sony AVC with the highest bitrate setting 25mb/s.

What could be the issue here? I've had the dirty fades problem several times with V13 already, and I can't seem to find a solution.
Thanks!

Comments

monoparadox wrote on 2/4/2016, 9:35 AM

Try setting project properties to 32 bit and increase render throughput which you have tried. Nonetheless, I've found some plugins and renderers don't support higher settings as wells as others.

-- tom

JJKizak wrote on 2/4/2016, 11:00 AM

I thought that banding was the result of too low a bitrate when the video was shot or transferred. But then again I am way behind the times.
JJK

tim-evans wrote on 2/4/2016, 9:53 PM

I've seen similar issues. Never could get rid of it with AVC. I experimented a lot trying to reduce or get rid of it. Rendering to uncompressed and I didn't see it so I knew it was in the encoder.

Rendering to MPeg2 for Blu-ray minimized it.

musicvid10 wrote on 2/4/2016, 10:30 PM

I can help this a bit, but it won't be cured until you shoot, render and play back in true 10 bit UHD.
First, that is easily the most demanding fade I have seen for loading down the encoder. I would love to have it my folder of extreme test clips called "Scourge of YouTube."

So, here is a starting workflow (only):
A. Open the video in a 32 bit project (it won't help the video itself).
B. Do all your compositing and effects layers at 2.2 gamma.
C. When it all looks good, slap the Studio RGB filter on the preview, and render to Sony 10 bit YUV.
> If the file is too large, my next choice is 10 bit DNXHD.
> You will probably have to prelevel the video track separately.
D. Open the YUV intermediate in Handbrake, pick the High PRESET, check Web Optimize, Cropping 0000, Decomb Off (unless it's interlaced), Frame Rate Constant, set RF at 18, Audio to Auto Passthrough, and click Start.

I could tell you why this should show less banding, but I want to see if you see a difference first.

Mindmatter wrote on 2/6/2016, 12:18 PM

Many thanks for the suggestions Musicvid.
It's actually better, but still ugly.

here's the file:

https://www.dropbox.com/s/harvox903hlgybm/A7S-testnew-1.mp4?dl=0

I'd really love to hear your explanations as to why this is not turning out as it should. Is it Vegas? As mentioned before, I keep having this dirty fades issue with V13.

VMP wrote on 2/10/2016, 12:09 PM

I am curious to know if there is a solution to this banding issue too.

Rendering to Mpeg 2 was a bit better (in 32 bit mode).
But still the banding is very visible. On both Mpeg 2 and H264 out of Vegas.

The is how the timeline looks like:
Banding-test-project-timeline-VP13.jpg

The first is a black solid fade, the second part is faded by fading the gradient and the white BG Solid.

Link video sample:
Sony AVC/MVC - AVCHD 1920x1080-50i:
Banding-test-project-VP13.m2ts

MainConcept MPEG-2
HDV 1080-50i
Banding-test-project-VP13.m2t

Do other NLE have this issue too? Anyone tried it?

VMP

larry-peter wrote on 2/10/2016, 1:12 PM

With the vignette you're using over the footage, I don't see a way to eliminate the banding when rendering to an 8 bit format. The vignette plus the fade to black is producing more and more subtle gradations during the fade that can't be reproduced with 8 bits.
If there are still NLEs or encoders that allow for dithering the output you may reduce it some, but I think the 8 bit delivery format is the issue.

altarvic wrote on 2/10/2016, 2:35 PM

Film grain overlay can help sometimes..
Free 720p footage here (for test)

musicvid10 wrote on 2/10/2016, 3:32 PM

Mindmatter,
It actually looks quite a bit better here; your monitor is set for 32 bit, correct?
Maybe sleep on it and have another look.

musicvid10 wrote on 2/10/2016, 3:43 PM

atom12,
Vegas dithers the output, but it is a dirty pattern dither.
The 10 bit intermediate I detailed above gives the second result below.

10 -> 8 bit dither in Vegas (Mainconcept]

10 -> 8 bit dither in Handbrake (libav/x264)]

VMP wrote on 2/10/2016, 7:57 PM

Ok I have now solved the banding problem using Musicvids tips.

The steps I did:

Set Project to 32-bit floating point (Video levels)

Rendered as (Video for Windows (*avi)
HD 1080-50i YUV.
(Left the 'Project' tab Color space to 'Default')

To keep the file size small I have converted it again to AVCHD 1920x1080-50i
So now its 3,47 MB instead of the SONY YUV 745 MB.
Zipping Rar-ing the file makes it smaller too for archiving.

Preview: Banding-test-project-VP13-SONY-YUV-converted.m2ts

Some Notes:

(Referring to the timeline: Banding-test-project-timeline-VP13.jpg)
Fading into A. solid black on top gives better result than B. fading away the two source tracks. Option A. gives almost no banding whereas B. does still give banding.

This is the first time I am not seeing any banding (with option A.), the latest preview of Mindmatter has banding on my monitor too.

Media info about the rendered YUV file:

Video
ID : 0
Format : YUV
Codec ID : UYVY
Codec ID/Info : Uncompressed 16bpp. YUV 4:2:2 (Y sample at every pixel, U and V sampled at every second pixel horizontally on each line). A macropixel contains 2 pixels in 1 u_int32.
Duration : 7s 520ms
Bit rate : 829 Mbps
Width : 1 920 pixels
Height : 1 080 pixels
Display aspect ratio : 16:9
Frame rate : 25.000 fps
Color space : YUV
Chroma subsampling : 4:2:2
Compression mode : Lossless
Bits/(Pixel*Frame) : 16.000
Stream size : 744 MiB (100%)

VMP

VMP wrote on 2/11/2016, 3:51 PM

Mindmatter,

Have you tried this?

VMP

Mindmatter wrote on 2/11/2016, 4:38 PM

Thanks a lot VMP and Musicvid, will try this as soon as I'm back at the workstation.
Will keep you posted.

VMP wrote on 2/11/2016, 5:09 PM

Good to hear Mindmatter,

Looking forward.

VMP

Mindmatter wrote on 2/12/2016, 5:31 AM

OK fading INTO black from white actually yields somewhat better results, but there's still banding. I actually remembered someone suggesting this in an older thread of mine about the dirty fades in V13.

https://www.dropbox.com/s/5jdn4il4xqu9n02/A7S-test4-1.mp4?dl=0

I can even see it in the large uncompressed avi file. Not on the timeline tho, as mentioned.
My EIZO Cs240 should run on a 16bit LUT with the right input, so I guess there's no 8 bit visual limit here.
Unfortunately my Ediusb trial has run out, I'd be curious to see if this is an issue trelated to V13 only.

VMP wrote on 2/12/2016, 3:18 PM

What about this preview: Banding-test-project-VP13-SONY-YUV-converted.m2ts

Do you see banding in that? (Watch in fullscreen)

Did you fade into a solid?

VMP

Mindmatter wrote on 2/13/2016, 9:26 AM

VMP, on my EIZO Cs240 I see almost no banding at all in your file in option A.
Yes, what you see in my file is a solid black fading in on top of everything.