Visible banding in project with Sony Levels (sRGB) on video bus output FX

[John Rofrano]

[Rick Anvican] “had some colors go out of range (after grading) before applying Levels, what would you guys recommend to do in this situation?”

I recommend you use your video scopes and not let your levels or colors go out of range. If it’s just one color (e.g., red) then use the Color Corrector (Secondary) to single it out and bring it back into range. You need to control you ranges when you grade.

You can also try setting the Pixel Format in your Project Properties from 8-bit to to 32-bit Video. This may get rid of the banding because it uses higher precision math when calculating FX. Waring: this will increase rendering time but if it solves the banding problem then it’s worth it but try and keep your colors and levels legal before you resort to this.

~jr

http://www.johnrofrano.com
http://www.vasst.com

[Rick Anvican]

Hi John,
Colors in the project were graded with the sRGB range in consideration, I’ll try just putting Levels on those events with out of range colors, otherwise regrade them to legal colors.

Pixel Format set at 32bit(Video levels) does indeed reduce banding with Levels on, as well as on some events with slight posterization (artefact in the source), guess it’s worth a try, but I’ll just check that the plugins I’m using won’t cause problems during render.

I’ve always used 8bit in Pixel Format for my projects and only this one has stumbled me with the visible banding due to effects and feathered masking, perhaps it’s just the nature of the source footage I’m using.

Thanks.

EDIT: Just finished rendering with Pixel Format set at 32bit(video), it surprisingly took roughly the same amount of time (about 40 mins with Cedocida DVCPRO50) when Pixel Format was set at 8bit, I thought it would have taken 3 hours to complete.
There was one glitch where two events composited with “Screen” mode had patches of bright yellow and red in the render (events were in its original form with no effects/transitions applied), Levels(sRGB) was applied and colors after that according to the video vectorscope were in the legal range and luminance was bordering on 90 IRE(sRGB) but the artifacts remained. This only happens on 32bit(video) and not 8bit.

[John Rofrano]

You’re doing the right thing by keeping your projects at 8-bit. You only need to go to 32-bit to fix banding problems or if you are using 10-bit footage that could benefit from 32-bit processing. Otherwise 8-bit is preferred for most work.

~jr

http://www.johnrofrano.com
http://www.vasst.com

[Rick Anvican]

Actually I was amused when I saw the Pixel Format setting for my first project in Vegas and was tempted to change it, but I left it at the default 8bit because logic tells me that I’m working with over 10 million colors and not 256 colors so that should be plenty.

I rendered that particular part of the project with artifacts at 8bit instead because there wasn’t any visible banding on those two clips anyway and the color grading was done, after that smart-rendered the pre-rendered segments, so all was fine.
Did notice slight color changes (shift in hue) to the original grading when switching pixel format so probably it’s best to do some testing with source footage to check signs of banding due to masking, effects, etc., and then put the project together only after deciding on pixel format.

The 8bit pixel format had me wondering what causes the visible banding, whether is it because of a slight reduction of colors in the sRGB palette which I doubt or is it that the rounding errors are quite significant, I thought that Vegas had a 10bit mode at first…

[John Rofrano]

[Rick Anvican] “Did notice slight color changes (shift in hue) to the original grading when switching pixel format so probably it’s best to do some testing with source footage to check signs of banding due to masking, effects, etc., and then put the project together only after deciding on pixel format.”

Yes, this is why I recommend that most people use 8-bit. It avoids a lot of color problems.

~jr

http://www.johnrofrano.com
http://www.vasst.com

[Rick Anvican]

Thanks for your help.

I’ve read from one of your posts saying that your Quadro card is getting replaced, what problem caused it to fail if you don’t mind sharing? Could invest in a workstation card in future…

Media players like MPC-HC and VLC tend to convert sRGB to Computer RGB colors and it seems that only importing video files into Vegas would show their true colors, according to the scopes there are times when there are out of range colors and luminance for brief periods…

[John Rofrano]

[Rick Anvican] “I’ve read from one of your posts saying that your Quadro card is getting replaced, what problem caused it to fail if you don’t mind sharing? Could invest in a workstation card in future…”

I have no idea. I started getting BSOD’s with the Nvidia drivers and I would just reboot and keep working but on one reboot it came up in a very low res mode and I couldn’t even display my BIOS (the screen as all broken up) so I have no idea what caused it. It just failed. I’m just glad it was under warrantee because I couldn’t afford to buy another one right now because I’m saving for a Mac Pro. 😉

~jr

http://www.johnrofrano.com
http://www.vasst.com

[Rick Anvican]

I’ve had a few BSODs from Nvidia drivers (WHQL assured) in the past, so I’ve stuck with working ones and wait for big updates, there was a GPU bake method that could resurrect broken that have symptoms like yours with the broken BIOS screen, but the Quadro’s an expensive one, probably best not to even if it’s not under warranty,
anyway all the best saving for the Mac Pro!