Lingzhi Liu

Prediction-based adaptive transform coefficients scanning for inter-frame video coding

In H.264/MPEG-4 AVC, the quantized coefficients are typically scanned in a fixed zig-zag pattern. This fixed scanning order may not always be optimal for entropy coding. To achieve better entropy coding gain in inter-frame coding, we propose a predictive scan ordering scheme and show that additional inter-frame coding redundancy can be removed by our proposed method. The scanning orders are dynamically updated based on the probabilistic distribution of quantized coefficients in the previous frames. Extensive experimental results demonstrate that the proposed algorithm improves coding efficiency by an average of 3.62% and up to 5.63% with negligible additional computational cost.

Integration of Plane Mode with Multiple Predictor Sets in Intra Prediction for video coding

Current default intra prediction method in the current test model for the next generation video coding standard JCT-VC, Unified Intra Prediction, has up to 33 directional modes and only one non-directional mode, which is Intra DC mode. Having only one non-directional mode is insufficient for maintaining accuracy on prediction units with complex texture. In this contribution, Plane Mode is integrated as an additional non-directional mode and an improved Multiple Predictor Set method is introduced; the proposed new method for intra mode prediction is used to obtain higher accuracy for intra mode prediction in video coding. Experimental results have shown that coding efficiency is improved with the proposed method.

Uniform probability model for deriving intra prediction angular table in High Efficiency Video Coding

High Efficiency Video Coding (HEVC) is the latest international standard of video coding under development. In HEVC, the new technology of intra prediction, Unified Directional Intra (UDI), has shown significant improvement on coding performance. Comparing to the intra prediction of H.264/AVC, significant performance improvement was observed for all intra configured tests. In the HEVC Test Model (HM), a predefined angular table is used for generating predicted sample values of UDI. However, how the table is obtained was not clearly presented in the literature. This paper gives a detailed derivation and explanation based on a novel uniform probability model. With this novel model, angular table derivation method was investigated and the selection of table entries used in UDI prediction is well explained. Simulation results show that using the improved angular table proposed in this paper, Bjontegaard Delta (BD)-rate improvement is achieved for sequences with large amount of various textures, in both all intra high efficiency and low complexity configurations.