An apparatus for processing a video signal with N frames is provided. The apparatus includes an encoding module and a selecting module. The encoding module performs a 1st through a Nth encoding procedure. The 1st through the Nth encoding procedure respectively encodes the 1st through the Nth frame among the N frames in a full-image-encoding mode, encodes other frames in an adaptive-image-encoding mode, and calculates the data amount of the N encoded frames in each encoding procedure, respectively. The selecting module selects the N encoded frames with the smallest data amount among the encoding procedures been performed.