• Journal of Broadcast Engineering
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• v.11 no.4 s.33
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• pp.407-419
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• 2006

In this paper, an adaptive illumination change compensation method is proposed for multi-view video coding. In multi-view video, an illumination change can occur due to physically imperfect camera calibration, each different camera position and direction, and so on. These characteristics can cause a performance decrease in the multi-view video coding that uses an inter-view prediction by referring to the pictures obtained from the neighboring views. By using the proposed method, a compression ratio of the proposed method in the multi-view video coding is increased, and finally $0.1{\sim}0.6dB$ PSNR(Peak Signal-to-Noise Ratio) improvement was obtained compared with the case of not using the proposed method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.4
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• pp.774-780
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• 2017

This paper proposes an efficient binary arithmetic encoder hardware architecture for CABAC encoding, which is an entropy coding method of HEVC. CABAC is an entropy coding method that is used in HEVC standard. Entropy coding removes statistical redundancy and supports a high compression ratio of images. However, the binary arithmetic encoder causes a delay in real time processing and parallel processing is difficult because of the high dependency between data. The operation of the proposed CABAC BAE hardware structure is to separate the renormalization and process the conventional iterative algorithm in parallel. The new scheme was designed as a four-stage pipeline structure that can reduce critical path optimally. The proposed CABAC BAE hardware architecture was designed with Verilog HDL and implemented in 65nm technology. Its gate count is 8.07K and maximum operating speed of 769MHz. It processes the four bin per clock cycle. Maximum processing speed increased by 26% from existing hardware architectures.

• Journal of Advanced Navigation Technology
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• v.18 no.1
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• pp.67-73
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• 2014

Due to the development of the communication technology and the high-performance mobile device, the number of video streaming service user has been increasing. Video streaming services in the restricted network environments need error control to support users for the Ultra High Definition(UHD) video delivery. Packet-level FEC method was used to control the error for delay-sensitive video service, but it has a defect in huge occupation of network resources by redundant packets. In this paper, we proposed a packet-level FEC algorithm which maintains the video quality by previous FEC methods and also reduces the occupation of network resource in the restricted network environments. The proposed algorithm controls the redundant rate with using the delivery characteristic of the video coding technology, and improves the efficiency of network resources by reducing the traffic by around 33% in comparison with the previous FEC methods.

• Journal of Broadcast Engineering
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• v.15 no.5
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• pp.617-630
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• 2010

At 37th VCEG meeting in Jan. 2009, Toshiba proposed Quadtree-based Adaptive Loop Filter (QALF). The basic concept of QALF is to apply Wiener filter to decoded image after the conventional deblocking filter and to represent the filter on/off flag data for each basic filtering unit in a more efficient way of quadtree structure. QALF could enhance the compression performance of around more than 9%, but the structure of one filter for a decoded frame leaves room for further improvement in the sense that optimal filter for one region of a frame could quite different from the optimal filter for other parts of a picture. This paper proposes multiple adaptive loop filters for better utilization of local characteristics of decoded frame to optimize the region-based Wiener filters. Additional filters, proposed in this paper, cover separate spatial area of each decoded frame according to the performance of previously designed filter(s) to provide the flexibility of rate-distortion based selection of the number of filters.

• Journal of Broadcast Engineering
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• v.16 no.2
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• pp.190-206
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• 2011

We propose an adaptive combination scheme of intra and inter prediction modes, where uni-directional intra prediction, bi-directional intra prediction, and inter prediction method are adaptively selected in an EMB (extended macro block). For each EMB, after all inter blocks have been encoded and decoded, the reconstructed blocks are used as reference data for bi-directional intra prediction of other blocks. Whereas conventional intra coding scheme does not use the right and below side pixels of the current block as reference data, the proposed method uses those for bi-directional intra prediction mode. In this paper, we propose three advanced techniques; (a) filter design for bi-directional prediction, (b) adaptive coding order scheme which increases the chance to use the bi-directional intra prediction mode, (c) modification of syntax to represent coding order. The information for the coding order is informed to the decoder by using the modified syntax structure without adding any additional flag. The simulation results show that the proposed scheme reduces the BD-Rate by 0.5%, on average, compared to KTA.

• Journal of Broadcast Engineering
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• v.13 no.3
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• pp.388-400
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• 2008

This paper introduces a cost-effective method fur improving anchor picture quality of a multiview video coding scheme that is mainly based on chroma compensation. Proposed method is applied to both INTER $16{\times}16$ and SKIP modes in only anchor P-pictures. By testing using JVT common test conditions, simulation results show that proposed method can obtain the average BD-PSNR gains fur U and V as 0.136 dB and 0.127 dB, respectively, while maintaining almost same performance for Y (luminance). For the range of low bit-rates, it is observed that average BD-PSNR gains of Y, U, and V are 0.141 dB, 0.494 dB and 0.525 dB, respectively. Necessary computational complexity is very marginal because the number of anchor P-pictures is only 4.18% in comparison with whole coded sequences, however it can be found that the proposed method can significantly improve the coding efficiencies of color components.

• Journal of Broadcast Engineering
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• v.13 no.4
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• pp.516-527
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• 2008

This paper introduces a derivation method of both P-SKIP and B-SKIP modes for illumination compensation in the multi-view video coding scheme. In this proposed method, mismatches between IC flag and IC offset in P-SKIP mode are removed, and also computational complexity is far reduced in B-SKIP mode in comparison to a multi-view video coding scheme. In simulation results, proposed method has the almost same coding efficiency in comparison with the referenced coding scheme. However computational complexity in 11m-time decoding process is tremendously reduced, such that the average number of blocks that should be processed in P-SKIP mode is saved in about 7.47%, and the average number of operations per block in B-SKIP mode is saved in about 50.36% and corresponding average decoding time per block is also saved in 46%.

• Journal of Broadcast Engineering
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• v.18 no.2
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• pp.297-310
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• 2013

In this paper, we present a model-based video bit rate estimation scheme for reducing the bit rate while maintaining a subjective quality in many video streaming services limited by network bandwidth, such as IPTV services. First, we extract major parameters which serve as an indirect measurement of frame's bits. Using those parameters, the proposed bit rate estimation scheme can extract candidate frames. Finally, the bit rate of each segment is estimated by statistical analysis and a mathematical model based on a given target quality. In experimental results, we show that the proposed scheme can reduce the bit rate on average by 43% in low-complexity video while maintaining the subjective quality. To find the appropriate bit rate based on video contents, the proposed schemes can estimate the bit rate with neither the repeated full encoding nor subjective quality test. On average, the bit rate can be automatically estimated by encoding the candidate frames of 4%.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2006.11a
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• pp.127-132
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• 2006

Quantization in video coding plays an important role in controlling the bit-rate of compressed video bit-streams. It has been used as an important control means to adjust the amount of bit-streams to at]owed bandwidth of delivery networks and storage. Due to the dependent nature of video coding, dependent quantization has been proposed and applied for MPEG-2 video coding to better maintain the quality of reconstructed frame for given constraints of target bit-rate. Since Scalable Video Coding (SVC) being currently standardized exhibits highly dependent coding nature not only between frames but also lower and higher scalability layers where the dependent quantization can be effectively applied, in this paper, we propose a dependent quantization scheme for SVC and compare its performance in visual qualities and bit-rates with the current JSVM reference software for SVC. The proposed technique exploits the frame dependences within each GOP of SVC scalability layers to formulate dependent quantization. We utilize Lagrange optimization, which is widely accepted in R-D (rate-distortion) based optimization, and construct trellis graph to find the optimal cost path in the trellis by minimizing the R-D cost. The optimal cost path in the trellis graph is the optimal set of quantization parameters (QP) for frames within a GOP. In order to reduce the complexity, we employ pruning procedure using monotonicity property in the trellis optimization and cut the frame dependency into one GOP to decrease dependency depth. The optimal Lagrange multiplier that is used for SVC is equal to H.264/AVC which is also used in the mode prediction of the JSVM reference software. The experimental result shows that the dependent quantization outperforms the current JSVM reference software encoder which actually takes a linear increasing QP in temporal scalability layers. The superiority of the dependent quantization is achieved up to 1.25 dB increment in PSNR values and 20% bits saving for the enhancement layer of SVC.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.11a
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• pp.172-175
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• 2011

높은 효율을 가진 비디오 압축 코덱인 H.264/AVC는 예전보다 압축 성능을 향상 시키기 위한 방법 중 하나로 율-왜곡 최적화 기법이라는 것을 사용한다. 이 기법은 압축된 결과를 가지고 손실과 압축률 두 가지를 모두 고려하여 어떤 경우가 더 최적의 압축인가 하는 것을 판별하는데, 여기서 모든 경우에 대해 압축을 수행해야 함으로 이전 보다 몇 배나 높은 복잡도를 가질 수 밖에 없다. 이러한 문제를 해결하고자 하는 노력으로 본 논문에서는 SAHTD(Sum of Absolute Hadamard Transform Difference)라는 기준을 사용하여 이를 이용해 율-왜곡 최적화 기법을 사용하지 않거나, 사용을 최소화 하면서 압축 효율을 유지하는 방법을 제시하였다. 본 논문에서는 휘도 신호 $8{\times}$8과 $4{\times}4$블록을 위한 방법을 제시하고 있다. 이 두 가지 크기의 블록에 대해서 SAHTD값을 구해 SAHTD가 낮은 순으로 모드들을 정렬하고, 이것이 가장 낮은 3개의 모드를 선택해 이것 중에 MPM이 포함되지 않았을 경우에 대해서는 MPM을 포함해 4개의 모드를 선택해 압축을 수행하도록 한다. 여기서 얻은 모드들 중에 SAHTD값이 일정 값 이상 더 낮은 모드가 존재할 경우, 그 모드들에 대해서만 율-왜곡 최적화 기법을 수행한다. 이를 통해 최적의 모드일 가능성이 낮은 모드들에 대한 부가적인 연산 수행을 방지하게 된다. 휘도신호 16x16이나 색차 신호 압축의 경우에는 SAHTD를 사용하여 가장 낮은 SAHTD값을 갖는 모드를 최적의 모드로 결정한다. JM 참조 소프트웨어를 통한 실험결과 제안된 기법은 기존 JM의 방식에 비해 화면 내 프레임의 부호화 시간의 82.2% 감소와 0.042dB의 PSNR 감소율, 0.527%의 비트 증가율을 보여주었다.