Fri May 29, 2020 1:06 am
How is the output from the computer connected to an input of the switcher?
Are you using an UltraStudio or DeckLink device to connect both a key and a fill source (using two inputs on the switcher), or are you just sending an HDMI out (possibly through a converter) to only one input of the switcher?
If you are sending two outputs from one of the BMD devices (you will need one of the add-on modules to do this with versions of ProPresenter prior to 7), then set the background of the slide to be transparent and configure the fill and key sources appropriately for one of the keyers. Turn that keyer on to show the graphics. In this mode you could use either an upstream or a downstream key, but a DSK probably makes more sense.
If you are only sending one output from the computer, you will need to use either a chroma key or a luma key on the switcher to knock out the background.
If you use a luma key then you can also use either an upstream or a downstream keyer, and it will knock the black out of the source. Simply select the computer input as being both the fill and the key source when configuring on the switcher. In ProPresenter, make the background of the slides black, and make sure your text and other content is not black - it needs to be bright enough to get past the keyer.
If using a chroma key, pick a color (chroma green for example - 0 red 100% green 0 blue) and use that as the background color of the slides; don't use it (or anything close to it) in any of your text or graphics. Set up the switcher to do a chroma key as explained in the manual. A chroma key can only be on the upstream keyer, but allows you to use black in the graphics.
With a chroma key, transitions done by ProPresenter might not output quite as smoothly if parts of the graphics are transitioning between being opaque and being transparent, so you might consider having a consistent shape to contain them and rely on the switcher to do the transitions on and off the screen (have the computer output in place before turning the keyer on, and turn the keyer off before stopping the output from ProPresenter).
Sending both fill and key out from one of the BMD devices eliminates the limitations on color choices and avoids the transition smoothness problems as well, but it does mean extra hardware and tying up an extra input on the switcher to accept the key source.