  JCT-VC HEVC HM 16 includes a Coding Unit (CU) level adaptive Quantization
Parameter (QP) technique named AdaptiveQP. It is designed to perceptually
adjust the QP in Y, Cb and Cr Coding Blocks (CBs) based only on the variance of
samples in a luma CB. In this paper, we propose an adaptive quantisation
technique that consists of two contributions. The first contribution relates to
accounting for the variance of chroma samples, in addition to luma samples, in
a CU. The second contribution relates to accounting for CU temporal information
as well as CU spatial information. Moreover, we integrate into our method a
lambda refined QP technique to reduce complexity associated multiple QP
optimizations in the Rate Distortion Optimization process. We evaluate the
proposed technique on 4:4:4, 4:2:2, 4:2:0 and 4:0:0 YCbCr test sequences, for
which we quantify the results using the Bjontegaard Delta Rate (BD-Rate)
metric. Our method achieves a maximum BD-Rate reduction of 23.1% (Y), 26.7%
(Cr) and 25.2% (Cb). Furthermore, a maximum encoding time reduction of 4.4% is
achieved.
