BRAW for Chroma Keying???

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patfish

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BRAW for Chroma Keying???

PostMon Jul 05, 2021 4:27 am

Hi everyone!
Last week i did a chroma keying test in After Effects with our Pockets 6K (BRAW 1:3, 1:5, 1:8) against the old FS700+Odeysee Q7 (RAW (cDNG)) and it was a real disaster that i end up using the old FS700 for the job.

I have no idea what happend (i work with green screen since 15 years) but the 6K BRAW footage was "not keyable" (not usable) in After Effect at all while the Fotoage of the FS700 (cDNG) was a dream to work with.

Is this a BRAW After Effects problem? or is BRAW not designed for perfect Chroma Keying?
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Hendrik Proosa

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Re: BRAW for Chroma Keying???

PostTue Jul 06, 2021 7:56 pm

What was the problem exactly? You got blocks in the key? Braw compression is based on DCT transform so when pushed, you can get blocky artifacts.
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patfish

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Re: BRAW for Chroma Keying???

PostThu Jul 08, 2021 10:14 pm

Hendrik Proosa wrote:What was the problem exactly? You got blocks in the key? Braw compression is based on DCT transform so when pushed, you can get blocky artifacts.


Exactly! very ugly blocks and noise like i would use a compressed 4:2:0 footage out of an 8bit DSLR.
So you are telling me that all Blackmagic cameras are not good for VFX work because of BRAW?

What would be the best/your recommended format/settings for chroma keying with a Ursa Mini Pro or a Pocket 6K?

I´m a bit shocked because i bought 3 years ago a Ursa Mini Pro for our university, made some chroma key test with cDNG RAW and it worked like a dream. Whit this in mind (i never got a warning that the BRAW update would be a massive downgrade for my use case) i ordered now two Pocket 6K.

regards,
Pat
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Uli Plank

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Re: BRAW for Chroma Keying???

PostFri Jul 09, 2021 3:00 pm

Without some samples from your side, nobody can tell.
We found BRAW to key quite nicely if you are using one of the lower compression ratios.
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Hendrik Proosa

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Re: BRAW for Chroma Keying???

PostFri Jul 09, 2021 6:39 pm

patfish wrote:Exactly! very ugly blocks and noise like i would use a compressed 4:2:0 footage out of an 8bit DSLR.
So you are telling me that all Blackmagic cameras are not good for VFX work because of BRAW?

What would be the best/your recommended format/settings for chroma keying with a Ursa Mini Pro or a Pocket 6K?

I haven't had a need to key braw footage, so can't recommend anything about it. I know about potential macroblocking issues just out of interest in the format.

I did a massive project where we filmed with Ursa Mini Pro 4.6K to prores4444 and had no keying problems that I can recall. So possibly test this route with your cameras too.
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Ben Price

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Re: BRAW for Chroma Keying???

PostWed Jul 14, 2021 12:24 am

I'm about to shoot a bunch of green screen videos for a client with my URSA 12K (which only records in BRAW).

In preparation for the project, I've shot a number of test clips at Q5 in 4K and 8K resolution (delivering at 1080p) and haven't noticed any issues with artifacting.
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Hendrik Proosa

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Re: BRAW for Chroma Keying???

PostWed Jul 14, 2021 7:09 am

patfish wrote:very ugly blocks and noise like i would use a compressed 4:2:0 footage out of an 8bit DSLR.

Could you maybe share a test clip, would be interesting to take a peek. Any chance it was shot underexposed by accident? Decently lit braw should not have "unkeyable" properties.
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Kays Alatrakchi

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Re: BRAW for Chroma Keying???

PostThu Jul 15, 2021 7:21 am

This was keyed as Braw, I didn't notice any issues although the footage was a tad noisy.

>>Kays Alatrakchi
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patfish

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Re: BRAW for Chroma Keying???

PostMon Jul 26, 2021 2:55 pm

Hendrik Proosa wrote:
patfish wrote:very ugly blocks and noise like i would use a compressed 4:2:0 footage out of an 8bit DSLR.

Could you maybe share a test clip, would be interesting to take a peek. Any chance it was shot underexposed by accident? Decently lit braw should not have "unkeyable" properties.


I have to look if I still have these clips.
You know it was only a quick test between the FS700 + Q7+ and the Pocket 6k ... and while the 6k was awful, the FS700 was perfect to key. I exposed the green with around 65 IRE.
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patfish

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Re: BRAW for Chroma Keying???

PostMon Jul 26, 2021 3:07 pm

It's hard to tell in such a dark scene ;-) ...but in the close up, from the side I still notice some artifacts in the hair. But it does the job in this case :-) ...but that's not the point! ... the point is that my 9-year-old FS700+Q7+ does the job more than noticeable better in the same conditions, and that BMD made a physical downgrade of my URSA Mini Pro 4.6K for VFX work.

Is there an option to patch my URSA Mini Pro 4.6K back to the old cDNG. Firmware? It would be great to have one camera with full color resolution for all my VFX works.
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patfish

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Re: BRAW for Chroma Keying???

PostMon Jul 26, 2021 3:09 pm

Is there a BRAW-Option with no Color Subsampling planed? ...don't get why BMD forgot VFX with their portfolio?
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patfish

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Re: BRAW for Chroma Keying???

PostMon Jul 26, 2021 5:46 pm

Hendrik Proosa wrote:
patfish wrote:very ugly blocks and noise like i would use a compressed 4:2:0 footage out of an 8bit DSLR.

Could you maybe share a test clip, would be interesting to take a peek. Any chance it was shot underexposed by accident? Decently lit braw should not have "unkeyable" properties.


I have to look if i still have this test files on my notebook? You know, it was only a fast test between the Pocket 6K and my old FS700 + Q7+ Recoder (4K 12Bit Raw cDNG.) and the files out of the FS700 was perfect to key while the 6K BRAW files behave closer to that what I get out of my DRLS :-/

I expose my green with 65 IRE.
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patfish

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Re: BRAW for Chroma Keying???

PostThu Jul 29, 2021 8:21 am

I have to look if I still have some of this footage of this quick test. I exposed the green screen like every time around 65 IRE... this worked on the FS700 perfectly.

But! The point is, not, that it's somehow possible to key with BRAW in an "ok" quality ... The point is, that it's way better with an 9-year-old Sony Camera with an external Recorder that supports cDNG. RAW.

Is there a way to set the firmware of the URSA MINI Pro 4.6 back to stock (with cDNG) ? or does BMD plan a BRAW version with full colors (444) in the near future?

Regards,
Patrick
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Ellory Yu

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Re: BRAW for Chroma Keying???

PostWed Aug 04, 2021 1:26 am

For chroma keying, have you tried shooting at BRAW Q0? That's been suggested for chroma keying so you might want to give that a try.
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patfish

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Re: BRAW for Chroma Keying???

PostSat Sep 04, 2021 2:40 am

Ellory Yu wrote:For chroma keying, have you tried shooting at BRAW Q0? That's been suggested for chroma keying so you might want to give that a try.


Thx for your advice with Q0 I will try that soon!
Has no one a plan if it is possible to set a USRA MINI PRO 4.6K back to the CDNG Stock firmware?

regards,
Patrick

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