This IS the Avid L2: Re: [Avid-L2] Beating the Dead QT Gamma Shift Horse

Wednesday, January 13, 2016

Re: [Avid-L2] Beating the Dead QT Gamma Shift Horse - UPDATE

I've taken everyone's good counsel, and embarked on many tests in an effort to get an export out of MC that didn't end up with a severely gamma-shifted QT (on its way to a BRD for client review).

Quick refresher — this is a feature shot on the Epic. Footage was opened in AMA and fully transcoded to DNxHD 175. Sound was sync'd in the Avid. All subsequent offline work has been done in a true DNxHD MXF happy Avid environment, just the way I like it: no AMA.

So then upon the need to export, I tried doing the video mixdown to same-as-source (DNxHD 175) then exporting SAS, then opening in Encore and Compressor alike, but NO JOY! The result was crushed down and murky! I tried doing the video mix down to ProRes 422 HQ MXF then exporting SAS, then opening in Encore and Compressor alike, but NO JOY! The result was, again, crushed down and murky!

I tried all manner of codecs until finally… JOY! I did the video mixdown to DNxHD 175 then exported to Animation codec. And that did it. When I pulled the QT with Animation codec into Encore it read exactly as it appeared when working offline in MC. So there's something tagged in both the ProRes and the DNxHD video mixdowns that seem to tell downstream apps (such as Encore and even VLC) to gamma shift it.

Someone really should fix this.

In any case, maybe this is old news to many people out there in L2 Land, but it is a happy revelation to me that, at the very least, there's a way to get what I'm seeing in MC out to the app that makes my BRDs.

David Dodson

davaldod@gmail.com

On Jan 4, 2016, at 1:48 PM, bigfish@pacbell.net [Avid-L2] <Avid-L2@yahoogroups.com> wrote:

Sounds like you need to make some test exports using color bars. I have found that when I export QT ref to Adobe Media Encoder I have to check the RGB box if I'm going to make ProRes and XDCam 50 files from a DNX QT Ref. If I'm just making DNX the 601/709 works.

Rather then speculate export color bars and make a file. Link back to the file in ama and see what the level is. At least then you have a reference point. I find often times with Avid's QT Ref even though the essence of the video is 16-235 601/709 level the outboard applications seem to treat the files as RGB and wash them out etc... Then sometimes the opposite happens.

Since you are using SAS then export bars and ama link to the file. Are the bars coming back in at the correct level? Move on from there and rinse and repeat.

I do realize that test reference signals are just BS that old farts like me believe in and with networks wanting files without bars it must mean that I'm full of crap to suggest using bars but I guarantee that with a test signal you can find out where the shift is happening.

I have found in my Avid centric world the best assessment tool for me is an ama link back to the file. If you have aja or kona cards you could also use some of the tools to look at the raw file video essence and feed the cards output to a scope but I'm betting you are going to have to use the Avid's internal scopes. While Avid scopes aren't fun to work with if you are just checking color bars they should give you a reasonable idea of where the levels are going south.

---In avid-l2@yahoogroups.com, <davaldod@...> wrote :

Hi, Job, Yeah, I see it in everything i open it in. VLC. MPEG Streamclip. Even when I open the SAS export (whether it comes from a Mixdown to ProRes or Mixdown to DNxHD 175) in Encore, it's just shifted way dark. It's truly like it's coming out of the SAS export that way. I'm completely at a loss here.

David Dodson
davaldod@...

On Jan 4, 2016, at 12:23 PM, Job ter Burg (L2B) <Job_L2@...> wrote:

David, where are you seeing that gamma shift? I mean, what player are you using to watch the SaS export? Did you try and watch it in VLC player? That's the most transparent one, IMHO.

On 4 jan. 2016, at 16:44, David Dodson davaldod@... [Avid-L2] <Avid-L2@yahoogroups.com> wrote:

for me, it's coming out of the Avid, on SAS export as already gamma shifted dark.