GDI SDK Option?

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in sok isjeong

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GDI SDK Option?

PostFri Feb 17, 2017 2:45 am

We are developing player in the Windows 7 environment.

We are developing a player using the GDI part in the SDK provided by Blackmagic Design.

This item is "DeckLink studio 4K" card is used.

Here, the graphic image was output by applying "bmdModeHD1080i5994" option of GDI BmdDisplayMode Option.

However, the output image is divided into three parts as shown in the figure below and output.
To avoid this error, I would like to know what kind of option should be applied.
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Waqqas Sharif

Blackmagic Design

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  • Joined: Tue Oct 04, 2016 1:47 am

Re: GDI SDK Option?

PostMon Mar 06, 2017 3:23 am

The GdiExample sample outputs the frame by picking the first supported display mode (which in this case is NTSC) from the list of supported display modes on the device.

In the GdiExample sample, the place where it sets the display mode, you have modified it to use the 1080i50 display mode and you are creating a frame in NTSC size which can lead to the behaviour you are observing.

This scenario is not supported on Desktop Video 10.2.1 where it horizontally repeats the frame, whereas, in other versions of Desktop Video i.e 10.8.4, where the NTSC size frame is centered around the 1080i50 display size.

If your intent is to create both frame and display size in 1080i50 mode, then instead of using the first display mode, iterate over all the display modes and explicitly select 1080i50 display mode.

See example code:
Code: Select all
while (displayModeIterator->Next(&deckLinkDisplayMode) == S_OK)
{
   if (deckLinkDisplayMode != NULL)
   {
      if (deckLinkDisplayMode->GetDisplayMode() != bmdModeHD1080i50)
      {
         continue;
                }
      else
      {   
         break;
      }
   }
}


Hope this helps.

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