prores XQ - it is actually recording at 12 bit

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Troy Wuelfing

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prores XQ - it is actually recording at 12 bit

PostWed Nov 15, 2017 2:56 pm

I see a huge difference in the dynamic range for a raw and the prores XQ.
can someone provide an explanation as to why i see these large differences?

thanks!
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roger.magnusson

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Re: prores XQ - it is actually recording at 12 bit

PostWed Nov 15, 2017 3:40 pm

Dynamic range should be exactly the same regardless of codec and bit depth. Are you perhaps recording in Video Mode instead of Film Mode?
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Denny Smith

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Re: prores XQ - it is actually recording at 12 bit

PostWed Nov 15, 2017 5:30 pm

The larger the bit depth, the greater amount of fine details will be recorded, and this is the difference you are seeing. Going from 10-bit to 12bit, is the same jump you will see going from 8-bit to 10-bit. You really see this difference when editing files, the larger bit depth allows for greater changes in color and image control in grading. The image does not fall apart as quickly when making exposure and color correction changes in post software like a Resolve.
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roger.magnusson

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Re: prores XQ - it is actually recording at 12 bit

PostWed Nov 15, 2017 5:34 pm

Yes, but to be clear, that has nothing to do with dynamic range.

Besides, the ProRes XQ on what I presume to be an Ursa Mini is exceptionally good (even when compared to raw), so something must be set incorrectly.

How are you viewing the files?
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Denny Smith

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Re: prores XQ - it is actually recording at 12 bit

PostWed Nov 15, 2017 5:39 pm

I agree Roger bit depth does not affect dynamic range, which is often over rated. It is the combination of dynamic range and bit depth, along with the color gamut that determines the final image output quality, they all work together, and isolating one above the other often leads to confusion. We have marketing departments to thank for this confusion. :roll:
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Robert Niessner

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Re: prores XQ - it is actually recording at 12 bit

PostWed Nov 15, 2017 8:40 pm

Troy Wuelfing wrote:I see a huge difference in the dynamic range for a raw and the prores XQ.
can someone provide an explanation as to why i see these large differences?


Why not post some examples of the differences you are seeing? Would make it much easier to discuss.
Robert Niessner
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Troy Wuelfing

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Re: prores XQ - it is actually recording at 12 bit

PostThu Nov 16, 2017 12:58 pm

hey,
thanks for the replies.
i didnt have a great test to post the screen grabs of the scopes from until today.
they are now attached.

we are shooting with ursa mini pro 4.6k
we set to film mode.
the results of a raw vs quicktime XQ are attached.

we will want to be able to grade to UHD HDR10 or HLG on these files. I would love to shoot in prores, but it looks like we will end up with a lot less to work with if we do.

thanks for any advice!
Attachments
RAW capture.JPG
RAW capture.JPG (127.4 KiB) Viewed 620 times
Prores HQ capture.JPG
Prores HQ capture.JPG (111.35 KiB) Viewed 620 times
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Robert Niessner

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Re: prores XQ - it is actually recording at 12 bit

PostThu Nov 16, 2017 1:29 pm

You can't trust Premiere's Lumetri scopes for ProRes. I've found them to wrongly interpret bit depth of ProRes.
Better check this in Resolve or After Effects.
Robert Niessner
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Troy Wuelfing

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Re: prores XQ - it is actually recording at 12 bit

PostFri Nov 17, 2017 9:09 am

thanks for the tip to verify the premiere scopes, however i am not very familiar with resolve setup.
i did some googling and could not find the answer, perhaps someone here can tell me how to set divinci to 12 bit per channel for the video, i only have 10 bits as an option, but the files should be 12bpc.

thanks again for the help
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roger.magnusson

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Re: prores XQ - it is actually recording at 12 bit

PostFri Nov 17, 2017 9:58 am

In Resolve, all processing is performed in 32-bit float. Bit depth only comes into play when you're rendering, so choose an output codec with the bit depth you need.
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Sebastian Höglund

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Re: prores XQ - it is actually recording at 12 bit

PostFri Nov 17, 2017 12:29 pm

In the images of the scopes you presented it says HQ and not XQ witch is a big difference.

Prores HQ is a 10 bit 422 codec.

And the difference with prores 4444 XQ and ProRes 4444 is that the XQ also has an Alpha channel that helps when you are doing heavt post production effects.
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Rakesh Malik

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Re: prores XQ - it is actually recording at 12 bit

PostFri Nov 17, 2017 10:34 pm

Sebastian Höglund wrote:And the difference with prores 4444 XQ and ProRes 4444 is that the XQ also has an Alpha channel that helps when you are doing heavt post production effects.


Remember though that there's no real value in an alpha channel at recording time -- there's no information to seed it with. So the recording you get from the camera will seem to have a bogus alpha channel -- it's not a camera bug, just a redundant channel.

(In case that extra channel confuses anyone.)
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Mike Potton

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Re: prores XQ - it is actually recording at 12 bit

PostSat Nov 18, 2017 10:27 am

4444 has an alpha channel, XQ is 12 bit...

https://images.apple.com/final-cut-pro/docs/Apple_ProRes_White_Paper.pdf

Best to go to primary sources when trying to figure this kind of stuff out, the white paper is a great read for anyone shooting Prores on their BMD camera.
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Tommaso Alvisi

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Re: prores XQ - it is actually recording at 12 bit

PostSat Nov 18, 2017 10:34 am

Mike Potton wrote:4444 has an alpha channel, XQ is 12 bit...

https://images.apple.com/final-cut-pro/docs/Apple_ProRes_White_Paper.pdf

Best to go to primary sources when trying to figure this kind of stuff out, the white paper is a great read for anyone shooting Prores on their BMD camera.


Mike, ProRes 4444 is usually 12bit too.

Did you find 12bit in camera are recorded only for 4444 XQ?
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roger.magnusson

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Re: prores XQ - it is actually recording at 12 bit

PostSat Nov 18, 2017 11:00 am

Sebastian Höglund wrote:In the images of the scopes you presented it says HQ and not XQ witch is a big difference.

Prores HQ is a 10 bit 422 codec.

Yes, but that still doesn't affect the available dynamic range, just how many levels of information is available between the bottom and top of the range.
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John Brawley

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Re: prores XQ - it is actually recording at 12 bit

PostSun Nov 19, 2017 4:03 am

Tommaso Alvisi wrote:Did you find 12bit in camera are recorded only for 4444 XQ?


ProRes 444 is absolutely 12 bit.

JB
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