DeckLink 4k Extreme 3D capture in DirectShow

Ask software engineering and SDK questions for developers working on Mac OS X, Windows or Linux.
  • Author
  • Message
Offline

CodyJan

  • Posts: 1
  • Joined: Mon Jan 19, 2015 12:42 pm

DeckLink 4k Extreme 3D capture in DirectShow

PostMon Jan 19, 2015 1:55 pm

Hi guys,

My project is capture two 1080p SDI signals and render them in one VMR window(based on DirectShow framework), it works very well with "DeckLink Duo", but I can't get it from my supplier any more, they only have "DeckLink 4K Extreme". I checked the spec of 4K extreme, it has two channels chA and chB, so I thought it will be very eazy to compile the new card, but I found it not eazy after I bought the new one.

First, let me expaint my project before.
"DeckLink Duo" have two devices in DirectShow's source filter:
"Decklink Video Capture"
"Decklink Video Capture (2)"
so connect the output pins of both source filter to VMR filter, and do some configuration, it works very well.


"DeckLink 4K extreme" have two devices in DirectShow's Video Capture Sources:
"Blackmagic WDM Capture"
"Decklink Video Capture"
But both them only can show one signal (channel A). So I began to try Media Express, I change configuration of "Edit"->"preferents", still have only one signal in capture window.

I read SDK "Blackmagic_DeckLink_SDK_10.3.1", found that 4k extreme have 3D capture function, so i tried to modify sample "CapturePreview" follow SDK pdf 2.4.3.1, unfortunately, I failed.

After that I checked all DirectShow Samples in SDK 10.3.1, nothing about "3d capture" or "4k extreme", is that mean 4k extreme no longer compatible with DirectShow?

I'm out of juice, any one have same experience? is it possible to capture dual signals with 4k extreme in DirectShow framework? Any suggestion?

Thanks for your time.

Best Regards:
Cody
Offline

Chris Skepper

  • Posts: 2
  • Joined: Tue Mar 03, 2015 4:36 pm

Re: DeckLink 4k Extreme 3D capture in DirectShow

PostTue Mar 03, 2015 4:46 pm

Hi,

I have a very similar project, so I'm also interested in the answer to this question.

I've tried 2 x 1080i/50 SDI signals into channels A and B of the DeckLink 4K Extreme, but I've had no luck getting the data from both channels. I can get one channel if I select 1080i/50. But if I select what looks like the 3D video mode (1920 x 2160) I only get black frames.

Any suggestions?

Chris.
Offline

Brad Parker

  • Posts: 22
  • Joined: Fri Mar 01, 2013 11:12 pm

Re: DeckLink 4k Extreme 3D capture in DirectShow

PostMon Mar 23, 2015 4:58 pm

The 4K extreme card can indeed capture 3D video over 2 SDI channels (as well as over 1 HDMI), we have a product that relies on this feature. However what has changed since the Duo/Quad cards is that the signals must now be perfectly genlocked and in sync with each other, or it will refuse to capture in 3D (but 2D still works on ChA). This is something we have noticed that is completely undocumented. Once the signals are genlocked and you are properly enabling all of the right 3D flags in the SDK, then capture will work correctly. The sample "Capture" program provided with the SDK supports 3D capture with the "-3" command-line option, so you can give that a try after solving the sync issue.

If you are not able to genlock the signals, the solution we came up with was to use two "UpDownCross" Blackmagic converters synced with a Blackmagic Sync Generator, setup to just pass the 2 SDI signals through without any conversion turned on. This provided a genlocked pair of signals to the DeckLink card and we were able to capture just fine. Of course this way does not guarantee that your sources are _actually_ genlocked now, it is just retiming the signals to match up on the far end, so they still may be off by a frame or so from each other, but at least you will get an image.

There are also a couple settings in the SDK for modifying the genlock functionality that may help but I have not tried them yet.

Hope this helps.
Offline

Chris Skepper

  • Posts: 2
  • Joined: Tue Mar 03, 2015 4:36 pm

Re: DeckLink 4k Extreme 3D capture in DirectShow

PostFri Mar 27, 2015 3:55 pm

Thanks for the reply - that's useful info to have.

FWIW, we're now thinking that 2 DeckLink SDI 4K cards might be the best way for us to capture 2 channels which aren't necessarily genlocked.
Offline

Brad Parker

  • Posts: 22
  • Joined: Fri Mar 01, 2013 11:12 pm

Re: DeckLink 4k Extreme 3D capture in DirectShow

PostFri Mar 27, 2015 5:27 pm

You can also test this by connecting the same source to both channels with a splitter. If you get an image then it is definitely the genlock issue that's keeping it from working in 3D.

Return to Software Developers

Who is online

Users browsing this forum: No registered users and 17 guests