DC coefficient estimation of intra-predicted residuals in high efficiency video coding

This paper proposes a DC coefficient estimation algorithm for intra-predicted residual blocks in the High Efficiency Video Coding (HEVC) standard. Discarding the DC coefficient in the current coding block leads to a substantial bit-saving but produces at the same time strong discontinuities between this block and its neighboring reconstructed blocks. To overcome this problem, we propose an estimation algorithm for the DC coefficient, which solves an optimal offset in a closed-form in the pixel domain to recover the corresponding block edges. Test results show that our algorithm achieves 1.0% and 1.4% BD-rate reduction on average for luma and chroma as compared with HM-16.6, respectively, when the sign-bit-hiding (SBH) technique is disabled. When SDH is set on, namely under the common test condition (CTC), the BD-rate reduction drops slightly to 0.7% and 1.1% for luma and chroma, respectively. In the meantime, the test results show that both encoding time and decoding time increase only slightly (about 10%, without any special optimization on programming our proposed algorithm).