Video processing device and related video processing method

The invention discloses a video processing method and device. The video processing method and device are used for partially decoding video frames when sub-regions of a video are selected for watching. The method identifies and decodes data units and pixel blocks of the video frame required to display the sub-region, while bypassing data units and pixel blocks identified as not required to display the sub-region. A video encoder receives a plurality of cubic surfaces including a first configuration corresponding to a full-size 360-degree virtual reality image. Each cube surface corresponds to a different surface of the cube. The encoder reformats the received video frame by rearranging the plurality of cubic surfaces according to a second configuration different from the first configuration. The second configuration rearranges the six surfaces of the cubic 360 degree virtual reality image in order to fully utilize the line buffer and allow the line buffer to be narrower than the full size 360 degree virtual re