title: Blackmagic Design DeckLink
copyright: Copyright (C) 2011 Daniel R. Dennedy
creator: Dan Dennedy
description: Output audio and video using Blackmagic Design DeckLink
SDI or Intensity HDMI cards. notes: Please ensure that you use a MLT profile that is compatible with a broadcast standard which the card you are using supports.
- Only internal keying is supported at this time.
- Only 8-bit Y'CbCr or RGBA (key) is supported at this time.
title: Pre-roll Count
description: This controls the amount of buffering in the DeckLink
driver/library. Increase this if you get video tearing or choppy audio. However, as you increase the amount, you increase the risk of audio and video becoming out of synchronization.
title: Enable Keyer type: integer
description: Keying is the process of compositing MLT output over a live SDI input. The alpha channel of the MLT video controls the transparent areas, and the keyer supports alpha-blending. You can not control the compositing rectangle. Rather, the entire MLT output overlays the entire video input. Therefore, you must use MLT's compositing services to control the size and position.
title: Key Opacity
description: This controls the level of blending between the key and the input video. 1 is fully opaque and something near 0 is transparent. However, absolute 0 is considered as "not supplied" and also fully opaque. 0.5 is an evenly balanced blending of the key and input video.