High-Accuracy and Low-Complexity Fixed-Point Inverse Discrete Cosine Transform Based on AAN´s Fast Algortihm

In this paper, a high accuracy and low-complexity fixed-point inverse discrete cosine transform (IDCT) based on AAN´s fast algorithm is proposed for the approximation of the real IDCT. The proposed transform can be implemented with 16-bit multiplication and 24-bit addition operations. A common factor extraction algorithm is used to obtain a new set of real factors of IDCT whose integer approximations can be implemented with few arithmetic operations. A two-stage scale approach is proposed for constraining the dynamic range to a narrow range in scale part. The experimental results show that the proposed transform has significantly higher accuracy than the thresholds of IEEE1180-1190. The results of the proposed IDCT implemented into the decoder of MPEG-2 also show that the fixed-point IDCT achieves higher performance.