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Data Levels vs. "Automatic"

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ninetto makavejev
Data Levels vs. "Automatic"
on Feb 21, 2013 at 2:13:49 pm

Hello,
I've studied the manual on this but I am not quite clear of the best practices with my specific work flow.
I am using a Decklink HD Extreme card which is outputting via HDMI to a calibrated Eizo HD2441 monitor.

The color bars/material I export from a P2 Premiere project as a quicktime 10-bit MXF file show the full range of blacks down to 0. When I open this file in RESOLVE, the sub-blacks are all clipped to legal 16, which is unsettling, since some info that is there is no longer showing up on the monitor which is capable of RGB values. (not a broadcast monitor) As soon as I set the clip's attributes to "DATA LEVELS" instead of AUTOMATIC, bamm, the sub-blacks are back.

Would in not be correct to scale and conform the material with the sub-blacks (data levels) and when exporting or round-tripping to Premiere to legalize the levels in the final master?
Or am I missing some crucial principle here, about how RESOLVE ingests/depicts 10-bit video?

thanks in advance, n.m.


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stig olsen
Re: Data Levels vs. "Automatic"
on Feb 21, 2013 at 11:00:34 pm

Hi,

My bet is that it is exported as 709 from Premiere.
If you export your clip as a RGB file, it will keep it full range or remap to full range if the material in Premiere has blacks set to 16.

Search for some of Peters posts on this.

Stig


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ninetto makavejev
Re: Data Levels vs. "Automatic"
on Feb 22, 2013 at 8:02:01 am

Thanks for the reply.
I did read a series of posts regarding gamma-shift and DNxHD, as well as the perils of not using a broadcast monitor...

Your diagnosis makes sense, but here's the take: I am just wondering WHY/HOW Premiere and Resolve communicate with each other. I do not understand why if e.g. I have a XDCAM-422 project, throw a test-chart/color bars on the timeline, export this "pure" in a 422 10-bit codec (e.g. DNxHD), bring it into RESOLVE and re-export "pure" in the same codec/container I see these black/gamma shifts when I bring the RESOLVE-export into Premiere?! Is Premiere always outputting RGB-values irregardless of codec/color space, but exporting 709? Maybe this is more of a Premiere oddity than anything to do with RESOLVE?
This is very confusing.

Hope someone comes up with the bottom line.


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stig olsen
Re: Data Levels vs. "Automatic"
on Feb 22, 2013 at 11:51:32 am

Hi,

I dont think what you are dealing with is a gamma shift issue.

Most editing softwares is not ment to output RGB (full range), so you need to make sure everything you import in Premiere is normal range. Meaning that the black levels are set to 16. If you have full range footage you need to import as RGB and it will then remap your footage to 709 (black at 16.)
Your monitor should be set to Rec709 and 16 will then be seen as pure black on your monitor.

When exporting to Davinci you need to export as RGB. It will then remap the footage to full range and the blacks will show as 0 on the internal scopes in Resolve.
Make sure you set the output to normal range.

When rendering to Premiere choose normal range.


Stig


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ninetto makavejev
Re: Data Levels vs. "Automatic"
on Feb 22, 2013 at 4:02:38 pm

Thanks Stig.
What you write makes perfect sense. It is just that, as I suspected, the logic of Premiere is very murky. Case in point: I can create a block of "black video" in a Premiere HD project and guess what - it creats a black video block of 0, not at 16, which one would expect in a 709 project. I will go thru all the Premiere settings and monitor levels once more and try to get a "round-trip" to RESOLVE that gives consistent results.


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stig olsen
Re: Data Levels vs. "Automatic"
on Feb 22, 2013 at 4:18:13 pm

Ok,

I dont know how it is handled in Premiere, but Avid / FPC works 709 internally and that is the way it should be in my opinion.
Flame, Davinci, Scratch etc works RGB internally, but they all have the option to set the output monitoring to normal range - as most people do. Then both the editing suites and finishing tools will match.

Note: Avid CAN output RGB through a Nitris DX (the only option) but that will cause a lot of other issues.

I find it strange that Premiere will not remap full range footage to 709 when import as RGB. It should.

Stig


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ninetto makavejev
Re: Data Levels vs. "Automatic"
on Feb 22, 2013 at 4:40:47 pm

Thanks. Yeah, it looks like Premiere, not RESOLVE is the culprit here. Although barely documented anywhere, it seems that Premiere works in RGB (0-255) and for anything else you have to set the levels MANUALLY on the the timeline with a levels effect, which seems a bit crazy.

At least according to these posts at the Adobe forum:
HERE http://forums.adobe.com/message/4287643
and HERE http://forums.adobe.com/thread/1138260

So it seems like the easy way to deal with round-tripping Adobe->Resolve would be to export/import with a RGB codec. Finish and legalize/export to 709 in Premiere at the very end.

Or does somebody have a better solution?


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ninetto makavejev
UPDATE: Data Levels vs. "Automatic"
on Feb 24, 2013 at 2:39:27 pm

An update after some tests: well, I am still not quite sure how Premiere handles 709 color space, but the only way I could get a 100% identical DNxHD round-trip was:

1. export from Premiere as 709 DNxHD 10-bit .mov
2. ingest in Resolve setting attribute as "DATA LEVELS"
3. Export from Resolve also with DATA LEVELS (not auto) in the output dialogue

I hope I do not run into any quirks when I finally legalize this project, but it was important to make sure no re-scaling values was occuring in this round-trip.


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