Method and device for obtaining minimal rate-distortion cost

The invention discloses a method and a device for obtaining minimal rate-distortion cost, belongs to the technical field of computer. The method comprises the following steps: obtaining a first code unit, wherein the first code unit is any code unit included in a video image; selecting parts of reference frames from a reference frame list; obtaining the first minimal rate-distortion cost of the first code unit based on a motion vector set and the selected parts of reference frames. The device comprises a first obtaining module, a selecting module, and a second obtaining module. The method and device are able to reduce the calculated amount of calculating the minimal rate-distortion cost, and increasing the efficiency of obtaining the minimal rate-distortion cost.