Method for controlling DCT computational quantity for encoding motion image and apparatus thereof

PURPOSE: A method and a device for controlling a DCT operation amount for encoding motion pictures are provided to utilize the operation amount allocated to a decoder at maximum rate and carry out the decoding for input bit streams normally. CONSTITUTION: A device for controlling a DCT operation amount for encoding motion pictures includes an encoder(320), a decoder(340), and a decoder complexity calculating part(342). The decoder complexity calculation part generates decoding complexity information for a previous frame(f(n)) when the decoding of the nth frame is finished. A DCT operation amount control part of the encoder controls the number to carry DCT of a DCT part(322) for a currently encoding frame(f(n+1)) among input image data by DCT skipping. The control of the DCT operation amount control part is carried out on the basis of the decoding complexity information transmitted from the decoder complexity calculation part. If a really consumed operation amount for the previous frame is smaller than an operation amount allocated to the decoder, the DCT skipping is reduced for frames after the current frame, thereby increasing the operation amounts of the encoder and the decoder.