Patent ID: 7161984

Claim:
A method of reproducing a compressed video signal, the method comprising: (a) variable length decoding the compressed video signal to detect quantized discrete cosine transform (DCT) coefficients and a motion vector, when the compressed video signal is input as a bit stream; (b) inversely quantizing the quantized DCT coefficients detected in (a); (c) performing an inverse DCT (IDCT) on the DCT coefficients obtained in (a) to detect a difference video signal; and (d) selectively performing post-processing on the decoded video signal, based on the motion vector detected in (a) and the characteristics of the difference video signal detected in (c), wherein selectively performing post-processing on the decoded video signal comprises: comparing the sum of the DCT coefficients of the difference video signal with a critical value; detecting if there is a motion vector when the sum of the DCT coefficients is smaller than the critical value; comparing the sum of AC components of the DCT coefficients with the critical value when the sum of the DCT coefficients is larger than the critical value; detecting if there is a motion vector when the sum of the AC components of the DCT coefficients is smaller than the critical value; and selectively post-processing the decoded video signal, depending on whether a motion vector is detected or not.