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Colours ruined after import (not QT)

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Simon Fly
Colours ruined after import (not QT)
on Apr 9, 2017 at 9:58:15 am
Last Edited By Simon Fly on Apr 9, 2017 at 11:27:45 am

Hi,

so there are many many threads regarding the same issue in this forum, but most of them boil down to the Quicktime Gamma bug, and I doubt that this is the problem in my case, since I do not use a QT format or QT for playback.

I'm working with H264/50fps footage and after importing it to premiere pro, the colours of the output are ruined, when comparing it to the original footage when viewed with VLC. The output then looks as bad when opened with VLC as well.

sample

What could have gone wrong during the import?

EDIT: When viewing the original footage with Media Player Classic, it looks also washed out.

BTW: yes, the footage is completely out of focus and fish-eyed and noisy, but still I'd like the colours to not degrade the output even more.


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Oliver Peters
Re: Colours ruined after import (not QT)
on Apr 9, 2017 at 1:33:54 pm

Which side is the original? How does it look in the Premiere viewer? Are any sort of default LUTs being applied either by intention or automatically on the master clips side?

- Oliver

Oliver Peters Post Production Services, LLC
Orlando, FL
http://www.oliverpeters.com


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Simon Fly
Re: Colours ruined after import (not QT)
on Apr 9, 2017 at 2:02:59 pm

Hi Oliver,

thanks for the reply, I made some discoveries in the mean time that indicate that this isn't premieres fault, which is why I tried to delete the original post, because I felt this wasn't the proper forum for this issue anymore.

Apparently, the footage was recorded with "limited" RGB (16-235) and VLC somehow extends that to full RGB 0-255. MPC doesn't do this, but there is a shader, which will extend the range to 0-255 as well, making the footage look the same in both programs. Because Premiere displays it as MPC would without the extra shader (i.e. using 16-235), I believe that this what it should be displayed like.

I couldn't find an option in VLC to display the range extension, however I managed to use Lumetri settings in Premiere to adjust the footage to my liking (i.e. remove that "grey curtain").

Do you know of any way to analyse the original footage whether it is "full" or "limited" RGB / YUV?


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Oliver Peters
Re: Colours ruined after import (not QT)
on Apr 9, 2017 at 2:10:41 pm

[Simon Fly] "Do you know of any way to analyse the original footage whether it is "full" or "limited" RGB / YUV?"

I'm not sure what MPC is, but typically all pro video is 16-235 (or a 10-bit or 12-bit variation of those numbers). Consumer video, which includes H264, is normally full range (0-255). I'm not sure if there's a way to tell in Premiere, however, you might try transcoding first. I normally use EditReady to transcode any of these prosumer formats (like drone footage) into ProRes, before bringing them into any NLE.

- Oliver

Oliver Peters Post Production Services, LLC
Orlando, FL
http://www.oliverpeters.com


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Simon Fly
Re: Colours ruined after import (not QT)
on Apr 9, 2017 at 2:21:56 pm

Sorry, MPC stands for Media Player Classic, a modern light weight video player, similar to VLC.

I will see if transcoding it beforehand helps, but usually I try to keep the number of transcoding iterations as low as possible to reduce quality loss.


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Oliver Peters
Re: Colours ruined after import (not QT)
on Apr 9, 2017 at 2:24:12 pm

[Simon Fly] "but usually I try to keep the number of transcoding iterations as low as possible to reduce quality loss."

Honestly, I understand. However, you are starting with H264, so transcoding to ProRes isn't going to hurt it. Even ProRes Proxy is a higher-quality codec ☺ Off course, I would recommend LT or standard as the target.

- Oliver

Oliver Peters Post Production Services, LLC
Orlando, FL
http://www.oliverpeters.com


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Simon Fly
Re: Colours ruined after import (not QT)
on Apr 9, 2017 at 2:40:47 pm

Well going from lossy to lossy is always going to introduce some degradation of the footage, no matter the quality of the two codecs.

Oh by the way, I'm using Windows so for using ProRes I would need some funky third-party software? Is it still worth it?


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Oliver Peters
Re: Colours ruined after import (not QT)
on Apr 9, 2017 at 7:15:52 pm

[Simon Fly] "Well going from lossy to lossy is always going to introduce some degradation of the footage, no matter the quality of the two codecs"

Yes and no. There's been a lot of research done regarding compression and the general rule is that the majority of degradation happens in the first generation as compared with uncompressed. Each subsequent compression step (assuming the same or less lossy codec) adds a considerably smaller amount of additional loss. Since you are starting with H264, you've already thrown out most of the potential quality in the recording. If you recompress that with a better codec, odds are that the next pass will at least be visually (not mathematically) the same - everything else being equal.

[Simon Fly] "I'm using Windows so for using ProRes I would need some funky third-party software?"

On Windows, encode to DNxHD instead. Probably using Adobe Media Encoder or Prelude.

- Oliver

Oliver Peters Post Production Services, LLC
Orlando, FL
http://www.oliverpeters.com


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Pat Horridge
Re: Colours ruined after import (not QT)
on Apr 10, 2017 at 3:13:58 pm

ProRes and Avid DNx are considered visually Transparent codecs, so the losses they introduce are subtle and visually difficult if not impossible to see.

Other codecs like H264 are lossy unless data rates are very high. Using multiple codecs introduces concatenation which is each subsequent codec adding artefacts on top of artefacts already present so you get compression elements being compressed. Never good.

So generally its best to either stay in the source codec if possible or transcode into a less lossey codec once and only once.

What you are describing re the levels is a level mapping issue. Studio levels (16-235 for 8 bit) are normal for TV work. full range levels (0-255 for 8 bit often refered to as RGB levels) tends to be used for the web and non TV work.
So mapping levels as you move content in and out of each type of "work" is an normal and important step.

Pat Horridge
Broadcast & Post Consultant, Trainer, Avid Certified Instructor
Free online Tutorials at VET digital media academy online http://vimeo.com/channels/752951
pat@vet.co.uk



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Simon Fly
Re: Colours ruined after import (not QT)
on Apr 10, 2017 at 3:20:18 pm

Hi Pat, thanks for the input.

So how would I find out which levels my original footage is using and can you recommend tools for level mapping (on windows)?


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Pat Horridge
Re: Colours ruined after import (not QT)
on Apr 10, 2017 at 3:23:07 pm

Well I'm an Avid user mainly so I just AMA link. Ensure no color adapters are applied (Avid like to try and apply the correct mapping) then I know what I see is unchanged by anything. I can then add LUTs level mapping etc as required.

Pretty sure Premiere can do the same with the interpret footage options?

Pat Horridge
Broadcast & Post Consultant, Trainer, Avid Certified Instructor
Free online Tutorials at VET digital media academy online http://vimeo.com/channels/752951
pat@vet.co.uk



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Chris Wright
Re: Colours ruined after import (not QT)
on Apr 9, 2017 at 2:54:05 pm

in VLC:
-tools-preferences-
set output to openGL video output and in vlc, effects, filters, disable video effects.
its pixels will precisely match premiere down to the RGB code.

also:
in nvidia control panel, change color range 16-235 to 0-255.


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