Apparatus and method for processing window for interlocking between mdct-tcx frame and celp frame

PURPOSE: An apparatus and method for processing window for interlocking between MDCT-TCX(Modified Discrete Cosine Transform-Transform Coded Excitation) frame and CELP(Coded Excited Linear Prediction) frame are provided to enable improved coding performance in a low bit rate by determining a window applied to a current sub frame if the coding mode of a preceding subframe or a subsequent subframe is in a CELP. CONSTITUTION: A window processing apparatus comprises: a coding mode decision unit(201) for deciding a preceding subframe coding mode and a subsequent subframe coding mode, with respect to a current subframe; and a window application unit(202) for applying a window that is determined according to the preceding subframe coding mode and the subsequent subframe coding mode, to the current subframe.