Slow capture card startup

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r0nj0n

  • Posts: 1
  • Joined: Tue Dec 10, 2019 9:52 pm
  • Real Name: Jeremy Mitchell

Slow capture card startup

PostTue Dec 10, 2019 10:01 pm

I am using the DeckLink Duo 2, and have downloaded and am using the latest SDK. I saw that in the SDK there was an example project known as CaptureStills, which seemed to be able to get me a picture off of one of the inputs. However, when i run that application it can take 1-2 seconds in order for the card to respond with an image using this project. I do notice that if I ask for more than one frame from the application, that it will capture the subsequent pictures quite quickly. Is there a setting on the card, or a way to always keep it "ready" so that if I ask for a capture, it responds as fast as these subsequent requests appear to capture?

Thanks in advance.
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Cameron Nichols

Blackmagic Design

  • Posts: 273
  • Joined: Mon Sep 04, 2017 4:05 am

Re: Slow capture card startup

PostWed Dec 11, 2019 11:47 pm

Hi Jeremy,

When the DeckLink Duo 2 and Quad 2 cards are configured with half-duplex profile (ie each connector can be configured as either input or output), there will be a short delay from when IDeckLinkInput::EnableVideoInput is called to when the device locks to the incoming signal.

In addition, if you are using auto-mode detection, rather than specifying the input mode, then there will be a small delay of 1-2 frames.

You can minimize the delay of the captured frame by calling EnableVideoInput in advance and ignore incoming frames until capture is required - perhaps by adding a getchar() to initiate capture.

Regards
Cameron

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