Efficient implementation of pre-filtering has been an important issue in video sequence coding, since it improves coding efficiency dramatically by alleviating camera noise. Based on the approximated generalized Wiener filtering and 2D discrete cosine transform (DCT) factorization, this paper introduces a novel pre-filtering scheme that is performed inside a video encoder. The proposed pre-filtering is performed, by scaling the DCT coefficients of original image blocks for intra block coding and those of motion- compensated error blocks for inter block coding, respectively. Even though the pre-filtering operation is embedded in a video encoder, its additional computational complexity is marginal compared to the encoding process, and the overall architecture of the conventional video encoder is maintained. In spite of its simplicity, the proposed pre- filtering scheme gives good filtering and coding performance for noisy video sequences.