Playback always seems to be yuv422 for SDI 4K

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Sunrise Wang

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Playback always seems to be yuv422 for SDI 4K

PostThu Oct 12, 2017 2:52 pm

Hi,

Apologies if this has already been asked before, I tried searching and couldn't find anything.

When playing back from the DeckLink SDI 4K, the output always appears to be yuv422, even though I've set the playback to something like rgbx10 (including performing the relevant conversions). I found this out when I was feeding the output of the card directly back into the input, the auto input detection was always picking up the signal as yuv 422, and playing it back correctly.

Is there an automatic conversion that happens somewhere? and is this a card specific thing? If so, is there a way to configure this somewhere so that this conversion doesn't occur?

Thanks in advance for your help
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Cameron Nichols

Blackmagic Design

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Re: Playback always seems to be yuv422 for SDI 4K

PostThu Oct 19, 2017 7:17 am

Hi Sunrise,

Can you detail the output display mode you are using? Be aware that only YUV modes are supported outputs in NTSC/PAL/2160p/4K video formats. You can check either by running DeviceList sample application or via DoesSupportVideoMode method[1].

Kind Regards
Cameron Nichols

References
[1] DeckLink SDK manual - 2.5.3.1 IDeckLinkOutput::DoesSupportVideoMode method
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Sunrise Wang

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Re: Playback always seems to be yuv422 for SDI 4K

PostThu Nov 02, 2017 1:10 pm

Hi Cameron,

Sorry for the late reply on this. My current setup is as follows:

-I enumerate all of the modes, and for each mode use DoesSupportVideoMode to check if the pixel format + mode combination is supported. If they are, I add them to a list which I can later use to select the mode + pixel format to run.
-I feed the playback of my capture card back into the capture slot, and start the capture with auto detect enabled
-Regardless of what pixel format/mode combination I use, the captured signal is always either yuv 8 bit or v210.

DoesSupportVideoMode seems to return bmdDisplayModeSupported for the rgba and rgbx10 formats for most modes as well. My capture card is a SDI 4k.

Thanks a lot for your help!
Sunrise
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Cameron Nichols

Blackmagic Design

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Re: Playback always seems to be yuv422 for SDI 4K

PostFri Nov 10, 2017 7:35 am

Hi Sunrise,

Can you let me know which video mode and pixel format you are targeting on output?

Kind Regards
Cameron
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Sunrise Wang

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Re: Playback always seems to be yuv422 for SDI 4K

PostMon Nov 13, 2017 7:35 am

Hi Cameron,

So this was happening with all modes an pixel format combinations, but for the sake of testing, rgba with 1080p60 should be enough to replicate this.

Thanks for your help
Sunrise
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Sunrise Wang

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Re: Playback always seems to be yuv422 for SDI 4K

PostMon Nov 13, 2017 1:28 pm

Oh apologies, so 1080p 30, since I believe I can't do 60fps with 4:4:4 rgb enabled (which I assume allows me to output in rgb mode?)
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Sunrise Wang

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  • Joined: Fri Sep 30, 2016 1:52 pm

Re: Playback always seems to be yuv422 for SDI 4K

PostTue Nov 14, 2017 1:25 pm

Hi Cameron,

I found the cause of the issue, thanks for the help! It turns out the mini converters were converting my formats to yuv for some reason.

Thanks,

Sunrise

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