Complexity Of HEVC Research Articles

Reference picture selection with decreased temporal dependency for HEVC error resilience

The high level of compression efficiency achieved by the High-Efficiency Video Coding standard (HEVC) decreases the robustness of the encoded bitstreams. This increased susceptibility to network errors leads to end video quality degradation. Moreover, due to the high computational complexity of HEVC, high-resolution video transmission with time constraints over hostile channels such as wireless networks becomes more challenging. This paper proposes a reference picture selection-based error-resilient method to reduce the temporal error propagation due to high-trip delay and frame-copy concealment error. First, the encoder selects the reference pictures based on the error status received from the feedback channel, taking into consideration the Rate-Distortion-Optimization (RDO). Second, the temporal information mismatch prediction resulting from the error concealment is reduced by decreasing the temporal dependency between adjacent frames based on new motion-estimation tools. Results show a PSNR gain of about 6.13 dB, 5.20 dB and 4.72 dB for 1080p, 720p and 480p resolutions respectively.

High-performance intra-mode accelerator for HEVC

The high efficiency video coding (HEVC/H.265) is the latest coding standard that reduces the bit-rate requirement by 50% compared to its predecessor, i.e., H.264. However, the coding complexity of HEVC is increased a lot not only due to its increased number of intra-modes (35 in total), but also due to its brute force methodology. In this article, a fast intra-mode decision strategy is proposed to reduce the complexity of HEVC. The proposed work first incorporates the statistical inference that was formed using the spatial/temporal data into the HEVC’s rough-mode-decision module. Then early termination is predicted by proposing a model that is based on the classical secretary problem (CSP). Thirdly, the uncertainty of the real world is introduced to the proposed CSP that outperforms the existing CSPs. Simulation results demonstrate that the proposed model is capable of achieving a minimum of 32.39% reduction in the total encoding time while the bit-rate (BD-BR) increment is limited to 1.33% on average.

Region-of-Interest Based Conversational HEVC Coding with Hierarchical Perception Model of Face

In this paper, we propose a region-of-interest (ROI) based HEVC coding approach for conversational videos, with a novel hierarchical perception model of face (HP model), to improve the perceived visual quality of state-of-the-art HEVC standard. In contrast to the previous ROI-based video coding approaches, this novel HP model allows the unequal importance of facial features (e.g., the eyes and mouth) within the facial region, by generating a pixel-wise weight map. Benefitting from such a perception model, the adaptive coding tree unit (CTU) partition structure is developed to alleviate the encoding complexity of HEVC, without any degradation of the visual quality in facial regions, especially in the regions of facial features. Subsequently, for the rate control in HEVC a weight-based unified rate-quantization (URQ) scheme, instead of the conventional pixel-based URQ scheme, is proposed to adaptively adjust the value of quantization parameter (QP). Such an adaptive adjustment of QPs is capable of allocating more bits to the face/facial features with respect to our HP model, and as a result, the visual quality of face, in particular facial features, can be enhanced for conversational HEVC coding. Finally, the experimental results show that the perceived visual quality of our approach is greatly improved, with even less encoding time, for conversational video coding on the HEVC platform.

적응적 탐색 영역을 이용한 HEVC 고속 움직임 탐색 방법

본 논문에서는 HEVC 부호화의 연산 복잡도를 줄이기 위한 고속 움직임 탐색 방법을 제안한다. 고속움직임 탐색을 위한 종래의 방법은 현재 영상과 참조 영상 간의 거리에 따라 탐색 영역의 크기를 조절하는 반면, 제안 방법은 예측 단위 간의 움직임 벡터 차의 유사성을 이용하여 예측 단위에 따라 움직임 벡터 탐색 영역을 적응적으로 조절한다. 실험을 통해 제안 방법은 random access 실험 조건에서 움직임 예측의 연산 시간을 약 10.7% 감소시키는 반면, 약 0.1%의 낮은 부호화 성능 하락을 가지는 것을 확인하였다. This paper proposes a fast motion estimation method which can reduce the computational complexity of HEVC encoding process. While the previous method determines its search range based on a distance between a current and a reference pictures to accelerate the time-consuming motion estimation, the proposed method adaptively sets the search range according to motion vector difference between prediction units. Experimental results show that the proposed method achieves about 10.7% of reduction in processing time of motion estimation under the random access configuration whereas its coding efficiency loss is less than 0.1%.

HEVC를 이용한 UHD 영상의 CPU 병렬처리 및 GPU가속처리

The latest video coding standard HEVC was developed by the joint work of JCT-VC(Joint Collaborative Team on Video Coding) from ITU-T VCEG and ISO/IEC MPEG. The HEVC standard reduces the BD-Bitrate of about 50% compared with the H.264/AVC standard. However, using the various methods for obtaining the coding gains has increased complexity problems. The proposed method reduces the complexity of HEVC by using both CPU parallel processing and GPU-accelerated processing. The experiment result for UHD(3840x2144) video sequences achieves 15fps encoding/decoding performance by applying the proposed method. Sooner or later, we expect that the H/W speedup of data transfer rates between CPU and GPU will result in reducing the encoding/decoding times much more.

Early Termination of CU Encoding to Reduce HEVC Complexity

Early Termination of CU Encoding to Reduce HEVC Complexity