Bug pixelling in BMPCC4k

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hugoo8

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Bug pixelling in BMPCC4k

PostThu Aug 04, 2022 12:13 pm

Hi everybody,

I'm writing to you because I encountered a bug for which I couldn't find an answer online on my blackmagic pocket 4k.

I've had it for 3 years and I had never encountered this problem until then, it appeared to me very recently.

I encountered an apparent square problem in the image. We see a kind of pixelation in the image which groups only a part of the image and which disappears quite quickly, then sometimes comes back. Something quite fluctuating. It's quite light and it does not group the whole image. We see quite large blocks, really like pixels but much larger.

I don't think it's a compression issue, I'm shooting in BRAW 12:1 and it's too big to be blocks of pixels anyway. Also, I didn't have this problem before with the same codec.

This bug appears really randomly, sometimes in motion, sometimes in fixed areas. I searched the internet for answers but couldn't really find any.

Do you know where it could come from? I haven't made any changes to my camera recently, nor has it deteriorated. I updated the software quite recently, I don't know at all if it can come from there.

Thanks for clarifying the point to me. You can see this problem in this video, especially in the red of the sweater : https://drive.google.com/file/d/1nbOrW8 ... sp=sharing

Thanks in advance,
Best regards,

Hugo Willocq
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roger.magnusson

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Re: Bug pixelling in BMPCC4k

PostFri Aug 05, 2022 9:11 am

Looks like compression artefacts. I would expect the reason is you've used the highest compression (lowest quality), BRAW 12:1. It will be bit-starved in very detailed shots, like in this wide shot with trees and grass. Not a bug in my opinion, just use a higher quality setting.

The file you shared is 8-bit 1080p DNxHR HQ, it would be interesting to see what the source file looks like.
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rick.lang

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Re: Bug pixelling in BMPCC4k

PostFri Aug 05, 2022 4:11 pm

Perhaps try switching to the constant quality settings such as Q1 and see if it looks consistently clean.
Rick Lang
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Jamie LeJeune

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Re: Bug pixelling in BMPCC4k

PostSat Aug 06, 2022 5:59 pm

roger.magnusson wrote:The file you shared is 8-bit 1080p DNxHR HQ, it would be interesting to see what the source file looks like.
Exactly. The issue could very likely be caused by the 8bit transcode or something due to the app that transcoded the file. Its best to share the original BRAW clip so that those variables can be avoided.
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hugoo8

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Re: Bug pixelling in BMPCC4k

PostWed Aug 10, 2022 11:03 am

Thanks for all your answer !

The original BRAW shows the same problem. It is not caused by transcoding. Also, sometimes, I can see this problem of pixelling directly on the screen of my bmpcc4k
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rick.lang

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Re: Bug pixelling in BMPCC4k

PostWed Aug 10, 2022 4:46 pm

Have you tried the suggestions to use a higher quality codec? Begin with the best quality such as BRAW Q0 or 3:1 to see if that’s good. Then try a lower quality and verify, and so on.
Rick Lang
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funkblaster

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Re: Bug pixelling in BMPCC4k

PostFri Sep 30, 2022 8:35 pm

I have the same problem.....

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