macOS 4K capture with magewell USB Capture SDI 4K Plus

[stephanschulz]

I have been using the magewell HD and 4k with a 4K Marshall camera successfully, when set to output HD resolution.
Now I’m testing the videoGrabber to capture 4k but the grabber sets itself to 2560x1440 even though

    vidGrabber.initGrabber(4096, 2160);

**[notice ] Device: 0: USB Capture SDI 4K+ #2**
**[notice ] 0: USB Capture SDI 4K+ #2**
**[warning] ofAvFoundationGrabber: requested width and height aren't supported. Setting capture size to closest match: 2560 by 1440**

Does anyone have experience with capturing 4K over this USB device?

[fresla]

**[warning] ofAvFoundationGrabber: requested width and height aren’t sup

Just in case, did you use the magewell application to set the device settings, maybe you need to set it to 4k there for it to be recognised.

[stephanschulz]

thanks for the reply.

yes I tried their software and set resolution to 4096x2160.
but the capture formate seems to get set by either quicktime or my OF app. but both don’t offer 4k.

[fresla]

I have an interest in this for an upcoming project, did you get anywhere? Could you make it capture at UHD instead of the DCI format, so 3840*2160, I see UHD as a standard capture preset in avfoundation: https://developer.apple.com/documentation/avfoundation/avcapturesessionpreset?language=objc_2

[stephanschulz]

Thanks for the tip. But it did not help.
OF still says 2560 1440 is the max res.
Nor quicktime or OF show a proper feed.

[stephanschulz]

It now works. All I changed was using a SDI cable that is sold as 4K capable. Not sure if that is really why it works now or if doing a reset on the SDI 4K unit helped.

[fresla]

SDI at 4k 30p is 6g and at 60p is 12g, that is a lot of data and for sure with a 1.5g (1080i60) or 3g 1080p60 cable it would not have worked. No idea why it did not give you the resolution though, maybe the capture box checks the impedance of the cable?