Decklink internal keyer BT.2020 support

I want to use the internal keyer of the Decklink 8K Pro to place an overlay on a live video image. Different input video formats should be supported and the input video properties (resolution, refresh rate, color coding, ...) should not be changed.
I set the output video mode based on the detected input video mode. This ensures that the resolution and refresh rate are correct. However, if the input signal has a BT.2020 color space, the color space is converted to BT.709 after keying. (If I have BT.709 at the input, the output is BT.709 as expected)

How can I control the color space on the output pin of the Decklink 8K Pro?

Here a screenshot of the DeviceStatusCSharp.exe from the Decklink SDK examples showing the difference between input and output signal:

Hello Juri,

You can set bmdDeckLinkConfigRec2020Output flag.

If set to true, device will output Rec.709 frames in
Rec.2020 colorspace.

Thanks for the reply. I hope that i can somehow avoid color conversions at it may lead to information lost or any type of modification of the incoming video signal.

By luck I saw the following changelog in the changelog of the new Desktop Video version 14.1.

New feature on DeckLink 8K Pro:
Add support for keying in Rec.2020, HLG and PQ.

This is exactly what i am search for, i think

In the decklink SDK documentation i did not find anything regarding this feature.
Is here a Blackmagic dev who could explain how this new feature works?

[Cameron Nichols]

Hi Juri,

To output a frame with Rec.2020, please use the following steps:

• If required, create IDeckLinkMutableVideoFrame object with IDeckLinkOutput::CreateVideoFrame[1].
• Create new class that implements both IDeckLinkVideoFrame and IDeckLinkVideoFrameMetadataExtensions with the following guidance[2][3]:
  
  • Provide created IDeckLinkMutableVideoFrame object to constructor, storing reference.
  • Release reference to IDeckLinkMutableVideoFrame object in destructor
  • Implement all methods of IDeckLinkVideoFrame providing wrapped calls to the local IDeckLinkMutableVideoFrame member.
  • Implement IDeckLinkVideoFrameMetadataExtensions::GetInt to return colorspace value bmdColorspaceRec2020 when metadata ID is bmdDeckLinkFrameMetadataColorspace[4][5]. Return E_NOTIMPL for other metadata IDs
  • The remaining IDeckLinkVideoFrameMetadataExtensions method should just return E_NOTIMPL.
  • Implement IUnknown methods with examples from SDK samples. QueryInterface should handle cases for IID_IDeckLinkVideoFrame and IID_IDeckLinkVideoFrameMetadataExtensions.
• Create an object with the custom interface and schedule output with the IDeckLinkVideoFrame as normal.

The SignalGenHDR sample should be used as reference, please have a look at the implementation of class HDRVideoFrame.

Regards
Cameron

References (DeckLink SDK manual)
[1] Section 2.5.3.9 IDeckLinkOutput::CreateVideoFrame method
[2] Section 2.5.5 IDeckLinkVideoFrame Interface
[3] Section 2.5.43 IDeckLinkVideoFrameMetadataExtensions Interface
[4] Section 3.65 Colorspace
[5] Section 3.61 Frame Metadata ID

Hello Cameron,

Thank you for your detailed reply!
We will try it out in the next few days

Hi Cameron,

Thank you for your detailed explanation. We have a few additional questions regarding this topic.

In the latest update to the DeckLink SDK (version 14.1), we noticed that the flags bmdDeckLinkConfigVideoOutputConversionColorspaceDestination and bmdDeckLinkConfigVideoOutputConversionColorspaceSource were added to the BMDDeckLinkConfigurationID enum.

Our question is: is it possible to use these flags to configure the input and output colorspace directly without having to override each frame of the output?

We’ve attempted to implement this in our C# application and have updated the SDK and DLL to version 14.2. However, we faced an E_NOTIMPL error returned from the dll when calling the IDeckLinkConfiguration.GetInt/SetInt(_BMDDeckLinkConfigurationID.bmdDeckLinkConfigVideoOutputConversionColorspaceDestination, out long destination) method.

We would greatly appreciate any assistance you can provide on this matter.

[Cameron Nichols]

Hi Yaroslav,

Configuration items bmdDeckLinkConfigVideoOutputConversionColorspaceSource and bmdDeckLinkConfigVideoOutputConversionColorspaceDestination are used to configure the output conversion pipeline for Dolby Vision output. Please refer to high-level description in section 2.4.12.3 in the DeckLink SDK manual for further information.

Accessing these configuration items will return E_NOTIMPL for targets that do not support Dolby Vision.

Kind Regards
Cameron Nichols