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Exporting as Rec 601

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Jason Brown
Exporting as Rec 601
on Apr 16, 2013 at 9:45:34 am

I first would like to thank the helpful members here at CreativeCow. I've posted more than a few questions and the fast replies has saved me on this project multiple times. I'm nearing the end of Post and have run into another issue... certain shots exported from Resolve are in Rec 601 instead of Rec 709. When I imported the graded Alexa Quicktime ProRes 4444 clips into Avid Media Composer, I see that the color space has changed to 601. When these shots originally came out of Avid to go to VFX, they were in 709.

Is this cause for major concern as 601 is an SD color space? I was unable to find any way to check export color space settings in Resolve. There may be something I am not understanding about 601 versus 709. I was under the impression that all HD content to be displayed on TVs or video projectors should be in 709.

thank you for your time.


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Joseph Owens
Re: Exporting as Rec 601
on Apr 16, 2013 at 4:53:51 pm

[Jason Brown] "Is this cause for major concern as 601 is an SD color space?"

Within an intelligent decoder like the Media Composer application, the simple answer is no.

If you attempt to play back 601 within a 709 environment that assumes all input will be 709, then, yes it would be a problem, mostly because the RGB -->Y' matrix coefficients are different. But Media Composer, knowing you are operating in 709, will (or should) flag the 601 media as requiring a different matrix extraction, and unify the media, exactly as if you were bringing legacy footage into a fresh edit timeline.

Why your Alexa footage somehow got flagged as 601 is the bigger mystery.

jPo

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


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Jason Brown
Re: Exporting as Rec 601
on Apr 17, 2013 at 5:00:44 am

Thanks for the reply. After further investigation, I've found that all of my rendered exports from Resolve are showing up listed as "YCbCr 601" in Avid MC, rather than "YCbCr 709" as it should be. I'm wondering if this is behind the degraded quality in blacks when viewing on my consumer HD monitor. I thought it was compression artifacting due to a 2nd generation ProRes 444 export, but perhaps it is from this color space issue?

The images look great in Resolve on my 10 Bit broadcast monitor, but running into lack of contrast and what looks like compression artifacts in darker graded scenes.


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Joseph Owens
Re: Exporting as Rec 601
on Apr 17, 2013 at 4:47:12 pm

[Jason Brown] ". I'm wondering if this is behind the degraded quality in blacks when viewing on my consumer HD monitor."

The consumer monitor may not be capable of reproducing the lower gray scale values that a grade monitor is expected to -- very unlikely to be able to support 10-bit, but almost certainly fudging the contrast ratio.

jPo

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


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Joakim Ziegler
Re: Exporting as Rec 601
on Apr 18, 2013 at 7:24:24 am

While I'm uncertain what's causing your colorspace issue, the visual problems you're seeing don't sound like they have anything to do with colorspace. Contrast and so on should look basically the same, the main diffenc you'll be able to see between 601 and 709 will be small hue/sat differences, mostly in blue-green tones.

--
Joakim Ziegler - Postproduction Supervisor


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Jason Brown
Re: Exporting as Rec 601
on Apr 18, 2013 at 7:58:41 am

Thank you for the reply. Most noticeable on all of the footage is a lighter contrast. On dark, graded scenes I do notice a magenta/purple shift in shots on the consumer HDTV that appear desaturated blue on the broadcast monitor.

I've run various export tests - 422, DNxhd, etc. to see if it improved the image. However exporting "Same As Source" still looks best at ProRes4444. I thought that perhaps the "Same As Source" function in Avid was exporting the final file in 10Bit as the source footage is, but this does not seem to be the case.


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