• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.7
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• pp.1663-1670
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• 2014

Recently, lots of research works have been actively focused on the DVC (Distributed Video Coding) techniques which provide a theoretical basis for the implementation of light video encoder. However, most of these studies have showed poorer performances than the conventional standard video coding schemes such as MPEG-1/2, MPEG-4, H.264 etc. In order to overcome the performance limits of the conventional approaches, several channel-divided distributed video coding schemes have been designed in such a way that some information are obtained while generating side information at decoder side and then these are provided to the encoder side, resulting in channel-divided video coding scheme. In this paper, the interpolation scheme by weighted sum of multiple motion-compensated interpolation frames is introduced and a new channel-divided DVC scheme is designed to effectively describe noisy channels based on the motion vector and its matching characteristics. Through several simulations, it is shown that the proposed method performs better than the conventional methods at low bit-rate and keeps the reconstructed visual quality constantly.

• Journal of Broadcast Engineering
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• v.15 no.2
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• pp.280-289
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• 2010

The H.264/AVC standard uses efficient inter prediction technologies improving the coding efficiency by reducing temporal redundancy between images. However, since H.264/AVC does not efficiently encode a video sequence that occurs a local illumination change, the coding efficiency of H.264/AVC is decreased when a local illumination change happens in video. In this paper, we propose an improved motion compensation using adjacent pixels and motion vector refinement to efficiently encode local illumination changes. The proposed method always improves the BD-PSNR (Bj$\o$ntegaard Delta Peak Signal-to-Noise Ratio) of 0.01 ~ 0.21 dB compared with H.264/AVC.

• ETRI Journal
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• v.34 no.3
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• pp.369-378
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• 2012

In this paper, we propose new adaptive search range motion estimation methods where the search ranges are constrained by the probabilities of motion vector differences and a search point sampling technique is applied to the constrained search ranges. Our new methods are based on our previous work, in which the search ranges were analytically determined by the probabilities. Since the proposed adaptive search range motion estimation methods effectively restrict the search ranges instead of search point sampling patterns, they provide a very flexible and hardware-friendly approach in motion estimation. The proposed methods were evaluated and tested with JM16.2 of the H.264/AVC video coding standard. Experiment results exhibit that with negligible degradation in PSNR, the proposed methods considerably reduce the computational complexity in comparison with the conventional methods. In particular, the combined method provides performance similar to that of the hybrid unsymmetrical-cross multi-hexagon-grid search method and outstanding merits in hardware implementation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.7
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• pp.1589-1596
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• 2010

In this paper, we propose the method that reduce computational complexity for intermode decision using CBP(coded block pattern) and coded information of colocated-MB(macro block). Proposed method classifies MB into best-CBP and normal-CBP according to the characteristics of CBP. On best-CBP, it eliminates the computation for $8{\times}8$ mode on intermode decision process because the probability for SKIP mode and M-Type mode is 96.3% statistically. On normal-CBP, it selectively eliminates the amount of computation for bit-rate distortion cost, because it uses coded information of colocated-MB and motion vector cost in deciding SKIP mode and M-Type mode. The simulation results show that the proposed method reduces total coding time to 58.44% in average, and is effective in reducing computational burden in videos with little motion.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2014.06a
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• pp.209-210
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• 2014

최근 인터넷 상에서 제공되는 영상 서비스에 대한 요구가 증가하고 있다. 하지만 네트워크 환경에서 전송되는 데이터는 오류로 인하여 쉽게 손실될 수 있다. 특히 HEVC(High Efficiency Video Coding)와 같이 높은 압축률로 압축된 정보에 대한 전송 오류는 영상 복원에 심각한 영향을 끼친다. 따라서 네트워크 환경에서 일정한 화질을 유지하기 위한 오류 은닉(Error Concealment : EC) 방법이 필요하다. 본 논문은 HEVC EC 를 위한 PU(Prediction Unit) 기반 움직임 벡터 외삽법(Motion Vector Extrapolation : MVE) 모델을 제안한다. PU 는 예측의 기본 단위로써 PU 내에 동일한 물체가 포함될 확률이 높다. 따라서, 이 모델은 손실된 프레임의 이전 프레임이 갖는 PU 정보를 이용하여 PU 단위로 외삽(extrapolation)을 실시한다. 또한, 손실된 블록과 외삽 블록간의 관계를 고려하여 겹쳐진(overlapped) 외삽 블록 중 가장 작은 PU 크기를 EC 기본 단위로 결정한다. 이 방법은 PU 정보를 반영함으로써 블록 경계 오류(block artifact)를 감소시킨다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.11a
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• pp.325-327
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• 2011

비디오 압축을 위한 움직임 벡터 부호화 과정에서 최적의 예측 움직임 벡터를 율-왜곡 관점에서 선택할 경우, 차분 움직임 벡터의 정보량을 최소로 만들 수 있지만, 추가적으로 예측 움직임 벡터의 인덱스 정보를 부호화해야 한다. 본 논문은 예측 움직임 벡터 인덱스 정보에 대해 모순 검증 기술을 적용하여 전체 예측 움직임 벡터들 중 모순으로 판명된 예측 움직임 벡터를 전체 집합에서 제외시켜 부호화 효율을 증가시키는 기술에 대해서 계층적 B 영상에 대한 새로운 실험한 결과를 제시한다. 제안하는 모순 검증 방법은 Motion Vector Competition 방법과 비교하여 평균 1.26%의 전체 비트량을 절감시킨다.

• Journal of Korea Multimedia Society
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• v.11 no.10
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• pp.1359-1365
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• 2008

The portion of header in H.264 gets higher than those of previous standards instead of its better compression efficiency. Therefore, this paper proposes a new technique to compress the header of H.264. Unifying a sentence elementary in H.264, H.264 does not consider the distribution of element which be encoded and uses existing Exp-Golomb method, but it is uneffective for variable length coding. Most of the header are block type(s) and motion vector difference(s), and there are redundancies in the header of H.264. The redundancies in the header of H.264 which are analyzed in this paper are three. There are frequently appearing symbols and non-frequently appearing symbols in block types. And when mode 8 is selected in macroblock, all of four sub-macroblock types are transferred. At last, same values come in motion vector difference, especially '0.' This paper proposes the algorithm using type code and quadtree, and with them presents the redundant information of header in H.264. The type code indicates shape of the macroblock and the quadtree does the tree structured motion compensation. Experimental results show that proposed algorithm achieves lower total number of encoded bits over JM12.4 up to 32.51% bit reduction.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.887-890
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• 1998

We present a novel multi-resolution block matching algorithm (BMA) for fast motion estimation. At the coarsest level, a full search BMA (FSBMA) is performed for searching complex or random motion. Concurrently, spatial correlation of motion vector (MV) field is used for searching continuous motion. Here we present an efficient method for searching full resolution MVs without MV decimation even at the coarsest leve. After the coarsest level search, two or three initial MV candidates are chosen for the next level. At the further levels, the MV candidates are refined within much smaller search areas. Simulation results show that in comparison with FSBMA, the proposed BMA achieves a speed-up factor over 710 with minor PSNR degradation of 0.2dB at most, under a normal MPEG2 coding environment. Furthermore, our scheme is also suitable for hardware implementation due to regular data-flow.

• Journal of the Korea Computer Industry Society
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• v.4 no.10
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• pp.761-767
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• 2003

In this paper, A Fast Multi-level Successive Elimination Algorithm (FMSEA) is presented for block matching motion estimation in video coding. Motion estimation accuracy of FMSEA is equal to that of Multilevel Successive Elimination Algorithm(MSEA). FMSEA can reduce the computations for motion estimation of MSEA by using partial distortion elimination technique. The efficiency of the proposed algorithm was verified by experimental results.

• Journal of the Korea Computer Industry Society
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• v.4 no.12
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• pp.1043-1052
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• 2003

In this paper, we present a fast motion estimation algorithm to reduce the computations of block matching algorithm for motion estimation in video coding. The proposed algorithm is based on Multi-level Successive Elimination Algorithm and Efficient Multi-level Successive Elimination Algorithms. The best estimate of the motion vectors can be obtained by hierarchical search point sampling and thus the proposed algorithm can decrease the number of matching evaluations that require very intensive computations. The efficiency of the proposed algorithm was verified by experimental results.