Bilateral adaptive quantization in HEVC

Abstract

In this paper, we proposed an adaptive quantization algorithm for High Efficiency Video Coding (HEVC) to boost the encoding performance. The transform coefficients in a Transform Unit (TU) inherit the energy concentration property. However, they are equally quantized before entropy coding. With equal quantization technique, the energy distribution of transform coefficients and the scanning pattern following the quantization stage is not properly considered. In order to quantize the coefficients adaptively, we proposed an improved algorithm to quantize the coefficients. For each coefficient, both the magnitude and its ordinal number scanned in entropy coding process are taken into account. The quantization parameter of each coefficient in a TU is adaptively calculated by the bilateral factors accordingly. We tested our method on the latest HM16.0. An average performance of -0.27% on BD-Rate and 7.07% computing time saving are achieved in the case of the commonly used Low Delay P configuration, which demonstrated the effectiveness of the proposed algorithm.