Blackmagic Forum

Hello,

I am trying to use the SDK to capture the fields coming from an interlaced signal and not the associated frame.
I would like to gte the field when they arrived to the card.

Is it possible ?

Thanks for answers,

Hi,

Just asked to support and get a answer. I post it here if it can help someone.

Our capture cards only grab frames and cannot grab individual fields of an image. You would have to do this as some form of post processing after acquiring the full frame of video.

I answered:

Then is it possible to get an information that a field is arrived ? Maybe
using the gen-lock ?

and get this:

Adding genlock would not change the functions of the SDK, all you are doing by adding genlock is providing the card with an external reference timing to use, instead of it's own clock. You are only going to be able to grab individual frames, so I don't believe there would be a way to know when a field has arrived, as the card is providing frames to the system.

So the answer to my first question is definitely : no.

Hope this helps someone someday.

I don't know exactly what you are trying to achieve but do you need quite such low-level access as the SDK? GStreamer can capture from Decklink cards and has a de-interlace filter from which you could capture fields. If you put a Tee in the pipeline and add 2 de-interlace filters one set to even, the other odd you would receive 2 streams, one per field.

Regards,

Dave.