The News, Explained
On November 6, Adobe announced a button in Premiere beta’s Sequence Settings that swaps width and height. A sequence is where you arrange video and audio in playback order. Its frame size determines how many pixels wide and tall each frame is. Premiere already lets editors type in those two numbers. The button removes the need to reenter them when you want to trade one for the other. Source Source
Say you have a 16:9 sequence that is 1920 pixels wide and 1080 pixels tall. Select it and swap the values in Sequence Settings to get a 1080 × 1920 frame with a 9:16 aspect ratio. Adobe says the button changes the frame dimensions and leaves the content where it was. If someone was standing off to one side in the horizontal edit, you still have to see whether they fit in the vertical frame. Adobe announced the button for the beta and gave no date for the regular release. Source Source
For the same 9:16 target, Auto Reframe Sequence does a different job. Adobe’s documentation says it creates a duplicate of the original sequence at the chosen aspect ratio and applies a reframing effect to each clip. The effect can move the view to help keep a subject in the new frame. When the action is fast or there are several points of interest in one shot, an editor may still need to adjust where the view moves. Source
OYOPICK’s Take
Imagine turning a horizontal interview into a short vertical video. If the speaker is already centered and you plan to place captions by hand, swapping the dimensions is a simple starting point. For a sequence that cuts between speakers on opposite sides, it may be more useful to make a vertical copy with Auto Reframe and review who stays in view in each shot. In either case, playing back the vertical edit and checking the captions and edges helps separate resizing the frame from editing the shot again. Source Source