Blackmagic Decklink cards

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Using BlackMagic Decklink cards

Description

Using BlackMagic Decklink cards

Declink specific settings

To activate the video capture of the Decklink card, the video VideoSize and VideoSubtype indexes must be set to 0, and the format must be specified by the VideoFormat index, e.g.:

VideoGrabber.VideoSubtype = 0 (default)
VideoGrabber.VideoSize = 0 (default)
VideoGrabber.VideoFormat = VideoGrabber.VideoFormatIndex ("HDYC 1920x1080 25 fps")
VideoGrabber.VideoInput = VideoGrabber.VideoInputIndex ("HDMI")
VideoGrabber.StartPreview()

Remark:
If there is no image (black video window), it is possible that the VideoFormat selected is not suitable.
To determine the proper video format, proceed as follows:
- run the pre-compiled MainDemo.exe
- select the Declink card in the VideoDevices list
- set VideoSubtype and VideoSize to default
- select the video input in the "Video Inputs" list
- select the video format in the "Video formats" list
- start the preview
then try each one of the video formats available in the "Video Formats" list, until you see the video capture.

Playout to the decklink renderer

The VideoRendererExternal property lets you activate the external renderer on the Blackmagic Declink card.

- to activate it, set VideoRendererExternal = vre_BlackMagic_Decklink
- to deactivate it, set VideoRendererExternal = vre_None

Note that the renderer requires a standard video size (e.g. 720x480 or 1920x1080).

By default TVideoGrabber resizes to 720x480.
To select the HD format, invoke UseNearestVideoSize (1920, 1080, true) before invoking OpenPlayer (to go back to the default setting invoke UseNearestVideoSize (0, 0, false))

Note that the Decklink renderer requires also a standard frame rate (e.g. 25 fps or 29.97 fps). If the clip has a non-standard frame rate it may fail to play on the Declink output.


Specifying the Decklink renderer to use when more than one Decklink card is installed in the same PC

If more than one Decklink card is used in the same PC, specify the card number to use to the VideoRendererExternalIndex property (in the 0..n-1 range).