Video levels above 255 / 1073 from MXF Sony into Resolve

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LarsBeach

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Video levels above 255 / 1073 from MXF Sony into Resolve

PostMon Dec 02, 2019 7:24 pm

Hi,

1.
DaVinci Resolve 16.1.1.005 / Windows 10

2.
Footage is a MXF Sony camera file 3840 x 2160. It contains spotlights directed straight into the camnera so there are definitive white clips in the file from the camera. Placing the clip on the timeline.

3.
i see something isn't quite right. I reach for the GAIN wheel in Resolve and turn it down. When I reach 0.90 I see the clipped spotlights right at 1073 on the scope.


QUESTION:

I have a feeling Resolve isn't interpreting the footage correctly. Or is Sony recording a file that contains data above 255? Not possible right...? A 16-235 interpretation issue? I haven't change any presets or prefs in resolve, just imported the file to the timeline.

If I transcode the MXF footage to ProRes 4444 or to DNxHD 444 and import that into Resolve then there is nothing hiding above 1073 when I pull turn down GAIN. However, the whites that were above 1073 have been clipped by that transcoding process.

So I have the feeling that the Sony MXF file contains real and valuable info that I don't want to lose. I can tweak each individual MXF file / clip manually to achieve this, but I'd prefer to see the import importing faithfully and correctly.


Any help appreciated
Lars
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LarsBeach

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Re: Video levels above 255 / 1073 from MXF Sony into Resolve

PostMon Dec 02, 2019 7:48 pm

If I view the Waveform Parade RGB in Resolve and pick a clip with a sky / sun / sunrise I see I can turn down GAIN as low as to 0.67 before the R gets below the 1023 line. There seems to be some vast amount of info above 1023.

(Sorry I wrote 1073 in my original post above. It should of course be 1023).

Lars
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Andrew Kolakowski

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Re: Video levels above 255 / 1073 from MXF Sony into Resolve

PostMon Dec 02, 2019 8:10 pm

Change video levels in Clip Attributes to Full.
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LarsBeach

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Re: Video levels above 255 / 1073 from MXF Sony into Resolve

PostMon Dec 02, 2019 8:27 pm

Andrew Kolakowski wrote:Change video levels in Clip Attributes to Full.



Thanks Andrew!

White clips in camera now land exactly on 1023 on the wave form scope.

QUESTION: What exactly did I do now by setting it to "full" ? Telling Resolve to interpret X as Y resulting in Z...?
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Uli Plank

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Re: Video levels above 255 / 1073 from MXF Sony into Resolve

PostTue Dec 03, 2019 10:49 am

Many Sony cameras record information in the 'Superwhite' area.
Resolve Studio and Fusion Studio under MacOS Mojave 10.14.6
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LarsBeach

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Re: Video levels above 255 / 1073 from MXF Sony into Resolve

PostTue Dec 03, 2019 4:28 pm

Thanks Uli for pointing this out. Looking a biit closer to this I see that:

1.
I set Clip attributes to FULL

2.
I look at the scopes and see black almost exactly at 64.

3.
I now look at the clip shot stright into a spotlight. Scope says exactly 1023.



A.
Think a little here shouldn't I see Black as 64 and White as 940...? After having done the "Clip attributes Full" ordeal....?

B.
If so, what you are saying is that the Sony camera adds a little extra there above 940? If I allow that to stay there (whats above 940) and make a DNxHD / ProRes copy/delivery to a TV-station - will there be problems? Or will the texture of the models hair and reflection in the water just look a littleextra crisp and nice...? What is the significance of allowing the Sony camera use that 940-1023 space?

C.
When I drop a clip from the ARRI Alexa Mini (ProRes 4444) 3800x1800 on the timeline and add the standard Arri Log C to Rec 709 I see that whites (windows, spotligths, reflections, etc) often reach around almost as high as the Sony. Not quite - around 1010 or so. This when "Clup Atributes" is set to "Auto" for this clip.

NOW... when I set clip attributes to "FULL" then the white peaks from the ARRI Alexa will get nailed to the 940 helpline that I set in the scope... (and image looking a little boring actually...)

In any case, the Alexa with LUT 709 seems capable of outputting levels above what Resolve is indicating as 940. What conclusion to draw from this?



Best,
Lars
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Andrew Kolakowski

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Re: Video levels above 255 / 1073 from MXF Sony into Resolve

PostTue Dec 03, 2019 4:36 pm

Sony cameras quite often use full range. It's also quite often user selectable in camera menus.
You should be able to check it also with mediainfo.
Resolve may not detect full range flag properly, so it's up to user to set it manually. At the end it's not that important if you grading- just try to recover as much details as possible (if one setting works better than other then it's doesn't matter much).
Grade to your desired look watching scopes (don't try to stay witting 64-940- fill whole range).

When you deliver final timeline using ProRes or DNxHD etc. leave default settings for levels (Auto). It will be properly converted to video range as it's required for broadcast.

You don't have to think about it too much.
You can have info all over the place. Not a single recording is perfect- there will be highlights clipping, etc.
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Cary Knoop

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Re: Video levels above 255 / 1073 from MXF Sony into Resolve

PostTue Dec 03, 2019 4:56 pm

LarsBeach wrote:I look at the scopes and see black almost exactly at 64.

That means that you should not set the clip to full levels but instead set it to video levels.

And having super whites is not unusual at all. You can bring them in if you like.

Note that on export you have an option to either retain the sub blacks/super whites or to clamp them.
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Uli Plank

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Re: Video levels above 255 / 1073 from MXF Sony into Resolve

PostTue Dec 03, 2019 7:52 pm

I normally stay in video and just pull those highlights down.
You should see in the scopes what is coming back in.
Resolve Studio and Fusion Studio under MacOS Mojave 10.14.6
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Andrew Kolakowski

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Re: Video levels above 255 / 1073 from MXF Sony into Resolve

PostWed Dec 04, 2019 12:46 pm

Black in Resolve scopes is at 0, not 64 (regardless if you exporting for broadcast or not). It's all properly converted to correct levels during export depending on chosen codec/settings.
Trying to stay within 64-940 (having in mind broadcast needs or not) in Resolve scopes is simply wrong.

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