H265 capture on an Ultrastudio 4K Extreme 3

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smcgill1969

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  • Joined: Tue Mar 21, 2023 8:13 am
  • Real Name: Simon McGill

H265 capture on an Ultrastudio 4K Extreme 3

PostTue Mar 21, 2023 8:47 am

Hi All,

Firstly, apologies if this is the wrong part of the forum.

I have an Ultrastudio 4K Extreme 3 and want to capture from a HLG/BT2020 source, problem is when I set it to h265 capture it changes the source profile to Rec709 and crushes all the colours. So I put a BiDirectional SDH/HDMI 12G inline and installed a 'real-time' LUT but that doesn't fix the issue.

If I set Desktop Video to capture as ProRes it leaves the source profile at HLG/BT2020. I can then apply the same LUT in resolve and export out as h265 without issue - it's just way too slow doing it that way.

Can anyone tell me if this is possible? Am I barking out the wrong tree, or (hopefully) have I just just got the settings wrong...? ;)


FYI;

4K Receiver - HDCP Stripper - Utratudio (ProRes Cap) = Works

4K Receiver - HDCP Stripper - Utratudio (H265) = Converts back to Rec709

4K Receiver - HDCP Stripper - SDI/HDMI 12G with LUT - Utratudio (H265) = Doesn't seem to help.


Also, just to confuse me some more, the preview window in Desktop Video shows the video as I would hope it's actually being captured!

Hope that explains my issue - as you've most likely guessed this is just for me, I am not a production technician by any stretch of the imagination... :)

Best regards,

Simon.
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smcgill1969

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  • Joined: Tue Mar 21, 2023 8:13 am
  • Real Name: Simon McGill

Re: H265 capture on an Ultrastudio 4K Extreme 3

PostThu Mar 23, 2023 10:53 am

Through a series of good luck more than judgement, I have just about got the LUT'd Rec709 H265 file recording sort of correctly now - one last issue remains though...

There seems to be no correlation between the Desktop Video H265 Quality settings and the recorded file!

Setting the H265 Quality to 10Mbps results in a file that is actually ~16Mbps - moving the setting to 12Mbps is giving me files that are >30Mpbps!!!

Is this a known issue?

Simon.
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smcgill1969

  • Posts: 3
  • Joined: Tue Mar 21, 2023 8:13 am
  • Real Name: Simon McGill

Re: H265 capture on an Ultrastudio 4K Extreme 3

PostFri Mar 24, 2023 4:18 pm

Fixed it!

Just in case it helps someone else, the reason I was getting wildly different compression outputs seems to be because I wasn't giving the H265 compression algorithm a chance to 'settle down'. My test files had all been around 1min in length, as soon as I tried a 1hr capture everything appears to be as I'd expect with the overall bitrate matching what I'd set in Desktop Video's preferences...

I'm a happy boy once more... :D

All the best,

Simon.

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