A transform size based quantization for high efficiency video coding

Abstract

Quantization is a key component in High Efficiency Video Coding (HEVC) standard. It enhances coding efficiency, and also introduces quantization distortion which causes degradation of the quality of the reconstructed video. In current framework, HEVC has adopted more transform sizes, and it is obvious that the transform unit (TU) with different transform size has different feature. A TU-level quantization technique, namely an adaptive quantization step size Q along with a fixed transform size is proposed in this paper. The proposed algorithm is implemented in HM software. Compared with HM anchor, the proposed TU-level quantization step adjustment (TUQA) method achieves an average of 0.32%, 2.34% and 2.58% BD bitrate saving for luminance and chrominance components, respectively. The largest BD bitrate saving is up to 1.0% for luminance and 3.8% for chrominance.