Software Development Kit for Blackmagic Design Inc. DeckLink series of
Editing/Design and Paint PCI cards, including samples and example code.

There is no direct download link for the source zip file which must be
downloaded via the Blackmagic Design web site at:
    https://www.blackmagicdesign.com/support
It requires registration and agreeement to the usage license conditions.
In the "Latest Downloads" column of the support web page, scroll to find the
"Desktop Video X.Y.Z SDK" section (where X.Y.Z is the required version) and
press the "Linux" button; then follow the instructions to download.