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Display Broadcast Safe Exceptions - how conservative?

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Paul Willis
Display Broadcast Safe Exceptions - how conservative?
on Oct 27, 2014 at 9:28:43 pm

Hi folks,

I've been wondering how conservative this feature is, I get exceptions in areas of red with almost any footage I work in.

I am not new to grading, but I'm new to delivering to broadcast. I have read a LOT on the subject and I understand that without hardware scopes I can't properly monitor out of range chroma in particular. A hardware legaliser and scopes is certainly on the christmas list!

Qualifying and desaturating specific problem areas is obviously hugely time consuming and impractical, and can result in a fairly dull image. Resolve's brick wall broadcast safe limiter is very aggressive and harsh and doesn't give me better results than qualifying the areas myself. Is the feature particularly conservative or am I just unable to properly monitor for issues and fix them in a less aggressive way until I have scopes?

I did a test with EyeHeight's new BroadcastSafe plugin for premiere. It appears to have a very minimal impact on chroma visually, much less so that what is required to bring problem areas into range in Resolve when viewing with broadcast safe exceptions. Resolve thinks the footage rendered out of premiere using eyeheight's plugin is largely still out of range, which baffles me again! I am making sure that video levels (64-940) are maintained throughout and there's been no interpretation issues between.

I'm tempted to run through EyeHeight's plugin for my master instead of Resolve's limiter, but I am not sure what to trust really. Anyone out there with scopes checked to see how well the broadcast safe exceptions work?

If it gets bounced back at QC, it's time to get the credit card out and invest in a legaliser, but I'm hoping to get through this first job without trouble.

Sorry there's a lot of questions in there, but any advice massively appreciated.


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Juan Salvo
Re: Display Broadcast Safe Exceptions - how conservative?
on Oct 27, 2014 at 10:35:48 pm

The conservativeness of the legalizer in resolve is set in the project settings page. Legalizing is about more than mantaining video scaled signal.

http://JuanSalvo.com
http://theColourSpace.com


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Paul Willis
Re: Display Broadcast Safe Exceptions - how conservative?
on Oct 27, 2014 at 10:52:57 pm

Thanks, Juan.

I understand the settings for the legaliser range, I've set it to 0-100 to be as safe as I can be. I'm just wondering why I get what I assume to be excess colour saturation in the shadows on so much of the footage, I guess I can't properly see where the problem areas are without a hardware vectorscope and I'm just ending up desaturating large areas of deep reds and lifting them out of the shadows.

The main thing confusing me was the wildly different ways in which the Resolve limiter affects the footage compared to the EyeHeight limiter. There's very little information on this product at the moment so I am not sure how reliable it is, but I guess with all software limiters there's no guarantee. With regards to the video scaled signal, I was simply referring to making sure that I was testing the clip was being interpreted the same way within Premiere and Resolve for testing purposes. I know exporting video scaled isn't going to ensure legality.


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Juan Salvo
Re: Display Broadcast Safe Exceptions - how conservative?
on Oct 27, 2014 at 11:42:04 pm

Legalization lies not in the saturation or luminance but in the cross over between the two. FWIW 0-100 is VERY conservative and I don't know of any broadcaster today that requires that. The mid step legalization should be enough for almost all broadcast.

http://JuanSalvo.com
http://theColourSpace.com


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Paul Willis
Re: Display Broadcast Safe Exceptions - how conservative?
on Oct 28, 2014 at 12:33:32 pm

Ahh, It seems that it is me that's being too conservative! I have been dubious of software legalisers so I went too conservative to be on the safe side. If it really is a hard limiter that shouldn't let anything through, then I'll ease off on it.

Thanks again, I'm still learning and still practicing and it's gradually falling into place.

Paul


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Joseph Owens
Re: Display Broadcast Safe Exceptions - how conservative?
on Oct 28, 2014 at 3:58:42 pm

[Paul Willis] "I have been dubious of software legalisers"

For the most part they are simulators trying to predict what will happen (based on RS170A composite baseband values) within a 0-100 RGB math model. As Juan responded, the real environment is the combination of luminance and chrominance (Y+C) which requires an encoding matrix.

In general, you are allowed -2 to 102 IRE in Luminance (on a 601 digital scale with a 0-100 luminance band, excluding analog pedestal of 7.5 IRE) and -20 to +120 Y+C for chrominance, which you cannot directly measure in a strictly RGB system.

The software systems say that you are okay if none of the RGB values are outside the 0-100 gamut -- in which case for example, color bars would be illegal, if they included the I and Q flags as those test patches generate illegal (negative) RGB values, even though they are part of the NTSC system.

Not trivial.

jPo

"I always pass on free advice -- its never of any use to me" Oscar Wilde.


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Paul Willis
Re: Display Broadcast Safe Exceptions - how conservative?
on Oct 29, 2014 at 4:08:40 pm

Thanks, Joseph.

That helps me get my head around the issues with software legalisers, I can see that there's never going to be a truly reliable solution with software. The EyeHeight plugin looks the most legitimate I've seen out there, it's made by a company that makes hardware legalisers and seems to justify its effectiveness with good documentation and does seem to work be being deliberately over conservative. However, I can see from your explanation that it can't ever be 100% safe.

This is always going to be a headache for people learning the craft, especially if they haven't begun their career working in a post facility that has access to the right hardware and experienced colourists to show them the ropes. I'm very thankful that the community is willing to offer advice on this stuff for those trying to learn at home.

It seems I may be lucky this time in that they want the grade delivered back to edit for online and titles, which means they're going to have to run it through a legaliser their end anyway. I'll work within the limits as best I can and apply a limit of -10-110 in Resolve for the time being. Time to build up my hardware arsenal when I receive the pay check!

Paul


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Paul Provost
Re: Display Broadcast Safe Exceptions - how conservative?
on Nov 2, 2014 at 5:35:37 am

How much was the eye height plugin?

http://www.filmandtvcolor.com | colorist | Los Angeles, CA

Twitter: @4kfinish


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Paul Willis
Re: Display Broadcast Safe Exceptions - how conservative?
on Nov 2, 2014 at 11:13:03 am

I've been running it in demo mode and it works 'for a few minutes' in export before disabling.

They're not a very transparent company, I had to email the sales director personally to find out any information at all. It's £495 to buy, which is a bit steep but if it works then it's great as it's extremely customisable and could save a lot of stress. You can also hire the plugin but they haven't got back to me on the pricing yet. I'm not sure why they have the pricing shrouded in such secrecy!

I wish I had a better idea how effective it was but there's very little information out there about it. It seems to claim that it will definitely work as long as you transcode to a high bitrate codec, which of course you would be doing anyway.


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Paul Provost
Re: Display Broadcast Safe Exceptions - how conservative?
on Nov 2, 2014 at 3:51:54 pm
Last Edited By Paul Provost on Nov 2, 2014 at 3:53:41 pm

Yeah there's no way I would pay that for a software legalizer plugin. Companies that don't do a lot or retail sales are often very opaque about pricing I guess to protect their dealers who seem to charge "as much as they can get." I ran into the same thing pricing close captioning years ago and from autodesk looking at flame and smoke like ten years ago. It took about two weeks and several meetings to get a price!
Honestly I used to use the plugin in final cut 7 for years doing online tape deliverables and never got kicked back from QC because of illegal video levels. Not once. This was standard def NTSC though.

http://www.filmandtvcolor.com | colorist | Los Angeles, CA

Twitter: @4kfinish


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