Hahyun Lee

Development of an ultra-HD HEVC encoder using SIMD implementation and fast encoding schemes for smart surveillance system

High efficiency video coding (HEVC) is the newest video coding standard that can support powerful video compression performance with increased picture resolution for ultrahigh definition (UHD). Compared to the previous standard, HEVC achieved a coding efficiency double with a tremendous increase in encoder computational complexity, making support of commercial applications for UHD video service difficult. Especially, optimized HEVC encoder for UHD is expected to be deployed as a key technology for an emerging smart surveillance system in Internet of Things environment. Single-instruction-multiple-data implementation on an Intel x86 processor and several fast encoding schemes were investigated for the complexity reduction of the HEVC reference model (HM) encoder. Fast encoding schemes included early termination processes and data-level parallel processing. The computational complexity of the proposed HEVC encoder was decreased by approximately 192 times compared with HM encoder with an acceptable coding loss.

High coding Efficiency video codec for entertainment-quality

We present a novel video codec for supporting entertainment-quality. It has new coding tools that are intra prediction with offset, integer sine transform with adaptive quantization matrix selection, uni-directional intra prediction, and enhanced block-based adaptive loop filter. These tools are used adaptively in processing of transform, intra prediction, and loop filtering. In experiments, the proposed codec achieved high rate reduction by average 14.77% BD-rate relative to H.264/AVC for 720p sequences.1

Intra Prediction Offset Compensation for Improving Video Coding Efficiency

In this paper, an intra prediction offset compensation method is proposed to improve intra prediction in H.264/AVC. In H.264/AVC, intra prediction based on various directions improves the coding efficiency by removing spatial correlation between neighboring blocks. In details, neighboring pixels in reconstructed block can be used as intra reference block for the current block to be coded when intra prediction method is used. In order to reduce further the prediction error of the intra reference block, the proposed method introduces an intra prediction offset which is determined in the sense of the rate-distortion optimization and is added to the conventional intra prediction block. Besides the intra prediction offset compensation, the coefficient thresholding method which is used for inter coding in JM 11.0, is used for chroma component in intra block, which leads the improvement of the luma coding efficiency of the proposed method. In experiments, we show that the proposed method achieves average 2.45% in High Profile condition and maximum 4.41% of bitrate reduction relative to JM 11.0.

A Prediction Cost based Complexity Reduction Method for Bi-Prediction in High Efficiency Video Coding (HEVC)

In HEVC, the fast search method is used for reducing the complexity of the motion prediction procedure. It is consisted of the sub-sampled SAD which reduce the complexity of Sum of Absolute Differences(SAD) calculation and the simplified bi-prediction method which reduce the iterations of the uni-prediction for the bi-prediction. The computational complexity is largely decreased by the fast search method but the coding gain is also decreased. In this paper, the simplified bi-prediction is extended to compensate the performance loss and the prediction cost based complexity reduction methods are also proposed to reduce the complexity burden by the extended bi-prediction method. A prediction cost based complexity reduction method is consisted of early termination method for the extended bi-prediction and the bi-prediction skipping method. Compare with HM 6.0 references S/W, the average 0.42% of BD-bitrate is decreased by both the extended bi-prediction method and the prediction cost based complexity reduction methods with negligible increasement of the complexity.