Strange problem with SDI DeckLink 4K adapter

I wrote an application that takes video from a custom camera, and outputs the video footage via a Blackmagic Design DeckLink 4k SDI card. The application itself allows the user to specify the format of the SDI output signal (1080p23.98, 1080p24, 1080p25, 1080p29.97, 1080p30, 1080p50, 1080p59.94, 1080p60, 1080i50, 1080i59.94, or 1080i60).

Everything works well except when the user selects either 1080p25, 1080p29.97, or 1080p30. In each of these cases the actual signal output from the DeckLink card is reported as 1080i50, 1080i59.97, or 1080i60, respectively. I am using a HyperDeck Studio Pro to report the SDI signal format.

I have triple checked to make sure that the selected output format matches the BMDDisplayMode parameter that is supplied to the EnableVideoOutput method of the IDeckLinkOutput COM interface. I have also triple checked that the EnableVideoOutput method returns S_OK when specifying each of the above problem formats.

Why is this happening?

Technical Details:
Operating system is Windows 8.1 64 bit
DeckLink 4K SDI driver version 10.6.1
DeckLink SDK version 10.6.1
Hyperdeck Studio Pro with 4.4.2 update


Code related to EnableVideoOutput method call:

Code: Select all

int attempts = 10;
HRESULT result;

while (attempts--) {
   result = this->device_output->EnableVideoOutput(this->display_mode, bmdVideoOutputFlagDefault);

   if (S_OK == result) {
      Log("SDI Video Output Enabled: display mode(%s) time scale(%d)\n", display_mode::to_string(this->display_mode).toLatin1().data(), this->time_scale);
      return true;
   }
}

if (S_OK != result) {
   return false;
}


Output of the Log calls for each of the problem formats:

Code: Select all

SDI Video Output Enabled: display mode(1080p25) time scale(25000)
SDI Video Output Enabled: display mode(1080p29.97) time scale (30000)
SDI Video Output Enabled: display mode(1080p30) time scale (30000)


[Nicholas Gill]

Hi Andrew,

My first thought is to check the Desktop Video Utility to confirm that the "1080PsF On" checkbox is un-checked. If this checkbox is on, 1080p signals will be output as their PsF equivalents.

If the checkbox is already off, could you please provide some more details regarding how the application configures the capture operation (i.e. usage of the IDeckLinkConfiguration interface)?

Cheers,

-nick

Hi Nick,

The 1080PsF On checkbox was indeed checked. Unchecking it has corrected the problem, and now the application outputs the correct 1080p25, 1080p29.97, and 1080p30 signals.

Thanks!
Andrew