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DeckLink SDK Qt Capture preview

PostPosted: Thu Jan 18, 2018 8:50 am
by Petar Petrov
Hello, does someone have a code example in Qt? The sdk includes MFC capture preview examples.

Ive found this project: But I couldnĀ“t get it working in windows with the new sdk (The project was made for decklink sdk 7.3)


Petar Petrov

Re: DeckLink SDK Qt Capture preview

PostPosted: Fri Jan 19, 2018 4:40 am
by Cameron Nichols
Hi Petar,

Unfortunately we do not yet have a Qt-based CapturePreview sample, we do have plans for this sample.

My advice is to refer to the Linux SignalGenerator sample, which uses a Qt-based screen preview with the IDeckLinkGLScreenPreviewHelper[1]. The same principle will apply for capture, both IDeckLinkInput and IDeckLInkOutput can register a class with base IDeckLinkScreenPreviewCallback[2] via SetScreenPreviewCallback()[3] method.


Refs (DeckLink SDK manual)
[1] 2.5.23 IDeckLinkGLScreenPreviewHelper Interface
[2] 2.5.22 IDeckLinkScreenPreviewCallback Interface
[3] IDeckLinkInput::SetScreenPreviewCallback method

Re: DeckLink SDK Qt Capture preview

PostPosted: Fri Jan 19, 2018 8:23 am
by Petar Petrov
Thanks, I will give it a go.

Re: DeckLink SDK Qt Capture preview

PostPosted: Mon Feb 19, 2018 9:28 am
by Petar Petrov
Im unsure how to preview the signal that is coming from an input.

I have succesfuly combined both SignalGenerator and Capture preview examples with Qt and I have the preview callback working. The issue is, I want to capture using FFmpeg which is an external binary and preview what is capturing from the api, the example of SignalGenerator manually creates the frames that are going to be shown to a IDeckLinkOutputDevice on a ScreenPreviewCallback. And in the other hand, the capture preview example, captures so it blocks my input device so ffmpeg cant capture.

How can I preview on a OutputDevice whatever is coming into an InputDevice no matter if im capturing or not?

Petar Petrov