This is very interesting. Now I wonder if there is any anomalies with how this LUT would interact differently between Avid Hardware and 3rd Party Software. My gut would say a LUT is a LUT and should react symmetrically with different IO hardware but I have experienced the Panasonic Vlog to Rec 709 LUT or it might have been the Arri LogC to Rec 709 generate different levels when running Avid 8,4,x and Avid 8.5.2. I confirmed that on my home system when I first saw it happen after taking a program home from work. The black balance shifted when I took a sequence from work done on 8.5.2 and opened it on my home system on 8.4.x.
When I upgraded the home system to 8,5,2 the black balance was corrected. I back revved to the 8.4.x just to be sure and the black balance went off again. Perhaps that was related to something similar to what the legalluts web site says about certain versions of 8.6 not working correctly with their LUT.
It seems with Avid's SCL there is most definitely a different response to the parameters depending on output hardware. I'd like to think this SCL behavior is limited to SCL but it would be interesting to check out the legal luts effect.
Great suggestion for an alternative as it would work virtually the same way I've been using SCL and I could renderit on an upper track.
For my novice geek side brain that grew up in analogue is it just the way the math transform of this LUT works that makes it a soft clip. A LUT basically takes a certain level/value and transforms it into a different value. I understand that a soft chroma clip would gradually reduce chroma gain as the overall luma increases to potentially illegal levels. In the math transform world of a LUT what does the math actually look at to perform a soft clip? Would it analyze the Y level and use that as a factor to influence how it remaps the U and V signals. I think I understand the Algorithm but not specifically how a math transform gets mapped out to achieve this. I Y level is say 50 percent then the chroma signals could be at normal chroma gain but when the Y is up at 95 percent then chroma signals would have to be rolled off in gain. Where does this math magic come from?
I don't know what amazes me more this kind of stuff or the math voodoo of codecs. It's all just magic and I know because the antenna on my roof collects electromagnetic magic and turns it into pictures on my TV.
---In Avid-L2@yahoogroups.com, <bogdan_grigorescu@...> wrote :
From: "Mark Spano cutandcover@... [Avid-L2]" <Avid-L2@yahoogroups.com>
To: "Avid-L2@yahoogroups.com" <Avid-L2@yahoogroups.com>
Sent: Saturday, March 4, 2017 10:55 PM
Subject: Re: [Avid-L2] More Safe Color Limit Whackyness going between Avid and 3rd party Hardware?
Well until I have another solution it's all I have for file based delivery. I just don't have the time to dick around with figuring out the limiter settings and possibilities of Adobe Media Encoder. I'm sure Clipster and other heavier iron offer such features. I'm too tired to think of the other big player that dub houses would try to sell us to legalize files etc... I would ask for a typical hardware legalizer like the DL-860 from Harris but they would say they didn't have one and suggested one of the higher end units that was used to correct the ABC spike gate FUBAR a few years back.
I understand the quirks of Safe Color Limit but never experienced the parameters reading differently on systems with Avid Hardware vs. 3rd party hardware. Responding differently is the crux of the problem but reading different numbers is just a whole new bowl of F.
Even before I started using 3rd party IO I would get different results with the 7.5 ire setting vs. 0 depending on project type. The basic suggestion has been to always start fresh in the current project.
Oh here's another great bug. After I build my safe color limit to reflect the -.1 luma low clip and save that effect to a bin I can then drag and drop it into the timeline and all is well. Luma low stays at -.1. But if I try to opt double click to apply the effect it ends up with a Luma low of 0. Makes it a major pain when switching systems and I can't just highlight all the safe color limits in the sequence and double click my bin save effect to apply it to all of them at once. It applies but not all the parameters come accross, with luma low being the big culprit but I think RGB lower limit defaults back to 16 or 0 when I've prebuilt the effect with 15 as the lower limit on RGB.
What other options are you contemplating to use instead? It's virtually impossible for me to not use Safe Color Limit as I use it to render the sequence out without rendering individual effects but there will come a time when I need to use some other method.
---In Avid-L2@yahoogroups.com, <cutandcover@...> wrote :Here is another situation where something just doesn't work correctly all the time, and again my advice would be: stop using it. Abandon "Safe Color Limit" because it is terribly untrustworthy.Do I have another solution for you? Not yet. I've been experimenting ever since I was burned by that black level lift. But I for sure will never use Avid Safe Color Limit again EVER EVER. It doesn't work.On Fri, Mar 3, 2017 at 11:05 PM, John Moore bigfish@... [Avid-L2] <Avid-L2@yahoogroups.com> wrote:On my MacPro 12 core OS 10.9.5 system I have a startup drive for DNxIO and one for NitrisDX. I find that when I create a safe color limit on the DNxIO startup Avid 8.5.3 I need to put -.1 for luma low and 15-235 other wise the limiter will raise the black level of 0 black slightly. That's nothing new but today I found if I open the same sequence on the same system using the NitrsDX hardware and the NitrisDX startup drive that does not have the Avid version of BM Video Desktop Software the same effect displays a parameter of luma low of 0 not -.1 WTF. I get that the different hardware units will respond differently with the Nitris DX need 7.4 in the luma low to achieve the same results but to change the read out of the parameter is whacky.When I go back to the DNxIO startup drive the same sequence and safe color limit effect reads correctly as -.1 in the luma low. This is really screwy. Regardless of whether the different hardware units will treat the parameter differently the number shouldn't be changing. And if it's going to change I would expect the -.1 value to shift to 7.4 which is the corresponding value for the same limiting on Avid hardware.The fall out is when switching systems you can really get hosed when legalizing and you can't even trust the effects window read out value.John Moore Barking Trout Productions Studio City, CA bigfish@...
Posted by: bigfish@pacbell.net
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