There is provided a method for automatically altering a digital video stream including multiple video input frames, to automatically obtain output frames with a target composition, in which frame metadata relating to objects in one or more of the video input frames is analyzed on a frame-by-frame basis and used by a processor to automatically alter one or more output frames to be more similar to, or to match, the target composition, wherein cropping is performed in 3D. A related system and a related computer program product are also provided.