Studio 12 introduces new Full Picture and Zoom scaling modes to allow images or video to match the timeline aspect ratio exactly with one click, avoiding "black bars" around some assets.
Two context menu items have been added: "Show full picture" and "Zoom picture to fill frame". The default is "Show full picture". If you select "Zoom picture to fill frame" for one or more clips, each clip will be scaled so that black bars are eliminated, zooming the 'smaller' dimension to fully fill the frame, and cropping the 'larger' dimension.
If multiple clips are selected, the scaling mode will be applied to all selected clips. The scaling options can be seen by right-clicking on the desired clip(s).