• Proceedings of the IEEK Conference
• /
• 2002.07a
• /
• pp.611-614
• /
• 2002

In this paper, a novel error concealment, algorithm is proposed for the MPEG-4 video decoding. Apart from existing algorithms which fail to exhibit stable performance over various video sequences and error patterns, the proposed algorithm adopts a new hybrid scheme, which can achieve a consistent performance with reduced computational complexity. This algorithm is implemented on the basis of the MPEG-4 decoder, and the experimental results demonstrate that the new approach provides acceptable performance both subjectively and objectively at various bit error rates and video sequences.

• International Journal of Internet, Broadcasting and Communication
• /
• v.12 no.1
• /
• pp.111-115
• /
• 2020

In this paper, I proposed an effective technique for accurately predicting pixel values using edge components. Adjacent pixel values are similar to each other. That is, generally, similarity exists between adjacent pixels in an image. In the proposed algorithm, edge components are detected using the surrounding pixels in the first step, and pixel values are estimated using the edge components in the second step. Therefore, the prediction accuracy of the pixel value is improved and the prediction error is reduced. Pixel value prediction is a necessary technique for various applications such as image magnification and confidential data concealment. Experimental results show that the proposed method has higher prediction accuracy and fewer prediction error. Therefore, the proposed technique can be effectively used for applications such as image magnification and confidential data concealment.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2014.06a
• /
• pp.209-210
• /
• 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 KSPS conference
• /
• 2004.05a
• /
• pp.235-238
• /
• 2004

Frame erasures cause speech quality degradation in wireless communication networks or packet networks. The degradation becomes worse when consecutive frame erasures occur. Speech coders have a frame erasure concealment(FEC) mechanism to compensate for frame erasures. It is meaningful to evaluate the performance of FEC mechanisms for frame erasures that occur in communications networks. In this paper, various frame erasures are designed. And the FEC algorithms of speech coders are evaluated and analyzed with the Perceptual Evaluation of Speech Quality(PESQ). It is found that the performances vary in accordance with frame erasure types, frame erasure rates, and utterance lengths.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2007.05a
• /
• pp.341-344
• /
• 2007

In this paper, a new temporal error concealment method for the new coding standard H.264/AVC is presented, which uses the high correlation between the motion vectors of neighboring blocks. By using the motion vector of neighboring MB of the lost MB, the MV of the lost MB are recovered. It is shown that under FMO coding method of H.264/AVC, the proposed method increases PSNR gain up to 2.85dB compared to build-in algorithm in the H.264/AVC test model and 2.59dB compared to Lagrange interpolation.

• Proceedings of the IEEK Conference
• /
• 2008.06a
• /
• pp.873-874
• /
• 2008

In this paper, we propose a packet loss concealment (PLC) algorithm for CELP speech coders, which is based on multiple adaptive codebooks by using comfort noise for the lost packet recovery. The multiple adaptive codebooks are composed of a conventional adaptive codebook to model periodic excitation of speech and another adaptive codebook to provide a better estimate of excitation when packets are lost in the speech onset region. The performance of the proposed PLC algorithm is evaluated by implementing it into the G.729 decoder and compared with that of the PLC algorithm employed in the G.729 decoder by means of perceptual evaluation of speech quality (PESQ). It is shown from the experiments under different burstiness of packet loss rates of 3% and 5% that the proposed PLC algorithm provides higher PESQ scores than the G.729 PLC algorithm.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2001.05a
• /
• pp.388-394
• /
• 2001

In this paper, a large number of algorithm have been proposed for error concealment and reconstruction real-time voice transmission for over the internet. The main purpose of this algorithm perform error reconstruction using low bandwidth and then guarantee good voice quality. Error concealment algorithm can be classified into receiver-based and sender- and receiver-based. In this paper, we apply the sender - and receiver-based reconstruction algorithm to low bit rate codec using CELP.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.7 no.8
• /
• pp.1776-1784
• /
• 2003

In this paper, we propose the architecture of stream producer for MPEG­4 Video encoding. This module receives the quantized coefficient from DCT and Quantization module in macroblock unit and performs the VLC coding according to the encoding mode, and supports the error concealment mode of MPEG­4 and data partitioning mode. Using the VHDL, we designed the module using this architecture and performed the evaluations of this module by performing the post­-simulation.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.22 no.5
• /
• pp.1107-1115
• /
• 1997

In this paper, we propose an error concealment method to recovre damaged block-based image coding schemes. Channel errors during transmission of image data such as bit errors or cell loss result in damaged image blocks in the reconstructed images. To recover damaged blocks is to estimate them using the correctly received or undamaged neighborhood information. In the proposed method, an overcomplete basis for a large block containing a damaged block at its center is introduced and damaged blocks are recovered by sequentially projecting the known neighborhood information onto the overcomplete basis function. Computer simulations show that the proposed algorithm outperforms the conventional method in subjectie recovery qualities as well as objective ones.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.39 no.6
• /
• pp.630-640
• /
• 2002

The compressed video bitstream is very sensitive to transmission errors. If we lost packet or received with errors during the transmission, not only the current frame will be corrupted, but also errors will propagate to succeeding frames. Error concealment is a data recovery technique that enables the decoder to conceal effects of transmission errors by predicting the lost or corrupted video data from the previously reconstructed error free information. Motion vection recovery and motion compensation with the estimated motion vector is a good approach to conceal the corrupted macroblock data. In this paper, we prove that it is reasonable to use the estimated motion vector to conceal the lost macroblock by providing macroblock distortion models. After we propose a new motion vector recovery algorithm based on optical flow fields, we compare its performance to those of conventional error concealment methods. The proposed algorithm has smaller computational complexity than those of conventional algorithms.