With the new release of ProPresenter, we no longer have “Modules” in our app. All things that were considered Modules are now fully standard as a part of the app. One of these features is the Alpha Keyer which gives the ability to send an Alpha Key output over SDI (with suitable output hardware) or NDI. Some SDI devices have special settings that are needed to properly work with the Alpha Key option here. These settings (if necessary) are outlined in their own section. This article will outline each output option. Please refer to this article to see which devices support Alpha Key
You first will need to make sure you have a suitable BlackMagic Device connected to your machine that allows for two separate output channels. You'll want to install the BlackMagic Desktop Video drivers for your device from www.blackmagicdesign.com. Once this is installed, you can open ProPresenter and begin setting up your Screen.
Open the Screen Configuration from the Screens tab in the Menu bar. From there, you will need to create a screen, and then assign this screen to your BlackMagic Device. Should your device support Alpha Key, you should see the Alpha Key tab in the linked screen configuration. When the Alpha Key is enabled on an SDI output, you can set what type of Key you wish to use (External or Internal) and also the percentage level of Blend that will be used. An External key would be used if you are sending separate key and fill outputs to your broadcast video switcher. It sends the key signal through the preview out of the BlackMagic device and the fill out of the program output. An Internal key would be used if you are using the Alpha Keyer as a downstream key, with a video input coming into the BlackMagic device and one going out of it.
An NDI output is simply sent out over your Network and can be picked up by a suitable NDI program/application or a hardware unit. When the Alpha Key is enabled on NDI, ProPresenter will send the rendered image out with an Alpha Key in place of the background color. This can be useful if you want to key your text on top of video, for example. There are no other settings when sending an NDI Alpha Key output, you simply can enable or disable the Key.
SDI using the BlackMagic 8k
The SDI setup inside of ProPresenter is the same no matter what output device you are using. There are changes that will need to be made for settings in the BlackMagic Desktop Video Setup though. Specifically using the BlackMagic Decklink 8K Pro, you need to go to the Connectors settings and select SDI 1& 2 In and SDI 3 & 4 Output for the best results.