Zero coefficient-aware fast IQ-IDCT algorithm

In this paper, we propose a zero quantized DCT coefficients-aware algorithm for the implementation of fast inverse quantization (IQ) and inverse discrete cosine transform (IDCT). In our prior work, we showed that zero coefficient-ware IDCT algorithm for fast decoding. In this paper, we extended a zero-skipping IDCT (Z-IDCT) by incorporating IQ with Z-IDCT. By adaptively skipping zero quantized coefficient computations, the proposed method can significantly reduce the computation time of IQ and IDCT in decoder. The decoding time of IQ and IDCT using the proposed method showed 36.7 percent speedup on average compared to that of MPEG-4 simple profile, and it also showed 9.6 percent speedup on average compared to that of Z-IDCT with MPEG-4 simple profile.