Google Research, together with collaborators from Georgia Tech, have developed an algorithm that resizes (or retargets) videos to fit the form factor of a given device without cropping, stretching or letterboxing. "Our approach uses all of the screen's precious pixels, while striving to deliver as much video-content of the original as possible. The result is a video that adapts to your needs, so you don't have to adapt to video.
Six frames from the result of our retargeting algorithm applied to a sub-clip of "Apologize", © 2006 One Republic. Original frame is shown on the left, our resized result on the right. The original content is fit to a new aspect ratio.
The key insight is that we can separate video into salient and non-salient content, which're then treated differently," explains Google.