How bmdDeckLinkConfigVideoInputConversionMode works?

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afriza

  • Posts: 3
  • Joined: Fri May 15, 2020 4:10 am
  • Real Name: Afriza N. Arief

How bmdDeckLinkConfigVideoInputConversionMode works?

PostSat May 16, 2020 8:44 am

Hi,

I have set bmdDeckLinkConfigVideoInputConversionMode to bmdVideoInputAnamorphicDownconversionFromHD720 but Media Express still detects the Input as 720 HD..

Is it supposed to automagically converts input or there are steps to be done?

As another try, I tried to set bmdDeckLinkConfigVideoInputConversionMode to bmdVideoInputAnamorphicDownconversionFromHD1080 but StatusMonitor example still detects the Input as 1080 HD..

OBS seems to be able to have the conversion applied though.. So what are the differences between OBS, Media Express and StatusMonitor example?
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afriza

  • Posts: 3
  • Joined: Fri May 15, 2020 4:10 am
  • Real Name: Afriza N. Arief

Re: How bmdDeckLinkConfigVideoInputConversionMode works?

PostWed May 20, 2020 8:41 am

I have done more testing.. and using AutomaticModeDetection sample, the converted DisplayMode is displayed.

However on my testing using Decklink Mini Recorder 4K:
HD 1080p50 is not converted to SD
HD 1080p25 is not converted to SD
HD 1080i50 is correctly converted to SD
HD 720p50 is correctly converted to SD

Is this hardware limitation, faulty unit, or... ?
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Cameron Nichols

Blackmagic Design

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  • Joined: Mon Sep 04, 2017 4:05 am

Re: How bmdDeckLinkConfigVideoInputConversionMode works?

PostFri May 22, 2020 2:42 am

Hi Afriza,

It is expected that 1080i59.95 will down-convert to NTSC (also i59.94) and 1080i50 will down-convert to PAL (i50).

Since Desktop Video SDK 11.5, you can check support for particular down conversion mode with IDeckLinkInput::DoesSupportVideoMode, eg:
Code: Select all
HRESULT hr = deckLinkInput->DoesSupportVideoMode(
    bmdVideoConnectionUnspecified,
    bmdModeHD1080i50,
    bmdFormatUnspecified,
    bmdVideoInputLetterboxDownconversionFromHD1080,
    bmdSupportedVideoModeDefault,
    &actualMode,
    &supported);
This call will output supported = true and actualMode = bmdModePAL. However if input display mode does not support input video conversion, output supported will be false.

Regards
Cameron

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