How can I preview my sources before switching?

Simply select the multiview to the HDMI output, then you can preview all of your sources, including the HDMI inputs and the media player, all on one screen. If you want to see a preview of a source before you bring it on air, you can change the ATEM Mini Pro switching style to program/ preview in the ATEM Utility. ATEM Mini Pro even supports previewing a transition feature so you can see how a key or transition will look before performing it on air.