Before proceeding, you must stop the Channel by deactivating the checkbox. Stopping the channel will also stop the playout.
Each Channel has a certain output format (frame size, frame rate, and bit depth) in which the engine is "rendering" the final output.
Stop the Channel by deactivating the checkbox in front of it. Stopping the Channel will also stop the playout engine and therefore the final output.
Select the Channel in the “Devices & Channels” list.
Click on the “Format” tab.
Select an 8bit based format in the “Output Format” drop-down menu or an RGBA format, in case you would like to play out Fill+Key.
Activate the checkbox in front of the Channel to start it again and to take over the changes you just made.
Keep in mind, that using a live input, the incoming live signal must match the Channel's frame rate and interlaced/progressive setting, otherwise it will not be visible in the final output.