Goo Rak Kwon

Video transmission adopting scalable video coding over time-varying networks

Recently, there is an active research about a new emerging video coding standard, scalable video coding (SVC). SVC adopts a layered coding scheme to generate multi-layered bitstream for heterogeneous environments. In addition to the layered coding, SVC performs temporal prediction using the hierarchical B picture scheme in order to provide temporal scalable representation of input sequences. Since the coding order of the hierarchical B picture scheme is different from that of conventional temporal prediction schemes, the layer-switching algorithm considering the different coding order has to be developed. In this paper, we first investigate the problems of layer switching in SVC and propose an algorithm that enables the SVC decoder to cope with layer switching caused by the bandwidth variation of networks. With the proposed algorithm, the SVC decoder can decode the time-varying sub-bitstream without modification of encoder. We confirm the proposed methods through the experiments.

An efficient POCS-based post-processing technique using wavelet transform in HDTV

In this paper, we propose a new post-processing method, based on the theory of the projection onto convex sets (POCS) to reduce the in digital high definition television (HDTV) decoded images. We propose a new smoothness constraint set (SCS) and its projection operator in the wavelet transform (WT) domain to remove unnecessary high-frequency components caused by blocking artifacts. We also propose a new method to find and preserve the original high frequency components of the image edge. Experimental results show that the proposed method can not only achieve a significantly enhanced subjective quality, but also exhibit the PSNR improvement in the output image.

Real-Time R-D Optimized Frame-Skipping Transcoder for Low Bit Rate Video Transmission

For the low bit rate (LBR) video communications, LBR transcoding is performed by the transcoder to match the network bandwidth and the performance of the client. One of typical transcoding schemes is a reduced temporal resolution reduction transcoding that enables adapting the bit rate requirements of a network by using frameskipping method. In this paper, in order to provide better visual quality for frameskipping transcoding while reducing computational complexity, we presents a new rate-distortion (R-D) optimized dynamic frameskipping (DFS) transcoder for LBR video transmission in the compressed domain. Experimental results show that the proposed transcoder performs better than the conventional frame-skipping method.

Fast inter-prediction method for mobile video communications using H.264/AVC

We propose a fast inter-prediction method to reduce the encoding complexity for the H.264/AVC coder. The proposed method determines the coding mode of the macroblock (MB) by using the characteristics of the motion compensated residual image. Experimental results show that the proposed method enables the H.264/AVC coder to be effectively adopted for mobile video communications.

Multimedia digital right management using selective scrambling for mobile handset

In this paper, we propose a novel solution called joint encryption, in which audio and video data are scrambled efficiently by using modified phase scrambling, modified motion vector, and wavelet tree shuffling. Experimental results indicate that the proposed joint encryption technique is very simple to implement, has no adverse impact on error resiliency and coding efficiency, and produces level of security.

R-D optimized frame-skipping transcoder for low bit rate video transmission

We propose a new real-time rate-distortion (R-D) optimized dynamic frame-skipping (DFS) transcoder for low bit rate video transmission. The proposed transcoder can adjust the number of skipped frames according to the target frame rate as well as the channel rate. Experimental results indicate that the proposed R-D optimized transcoder can not only perform frame-skipping effectively but also improve visual quality in the low bit rate video transcoding

Intellectual property rights management using combination encryption in MPEG-4

In this paper, we propose a new encryption method for intellectual property rights management of MPEG-4 coder. DCT coefficients and motion vectors (MVs) are used for the combination encryption of the MPEG-4 video. Experimental results indicate that the proposed joint and partial encryption technique provides levels of security and achieves a simple and coding-efficient architecture with no adverse impact on error resilience.

Multimedia digital rights management using modified motion vector for mobile device

This paper presents a new digital rights management (DRM) that modifies the motion vector (MV) of macroblock (MB) for mobile device. Experimental results indicate that the proposed DRM can not only achieve very low cost of the encryption but also enable separable authentication to individual mobile devices such as portable multimedia player (PMP) and personal digital assistants (PDA).

Improved POCS-based deblocking technique using wavelet transform in block coded image

This paper presents a improved POCS-based deblocking technique, based on the theory of the projection onto convex sets (PODS) to reduce the blocking artifacts in decoded images. We propose a new smoothness constraint set (SCS) and its projection operator in the wavelet transform (WT) domain to remove unnecessary high-frequency components caused by blocking artifacts. In order to eliminate the blocking artifacts component while preserving the original edge component, we also propose a significant coefficient decision method (SCDM)for fast and efficient performance. Experimental results show that the proposed method can not only achieve a significantly enhanced subjective quality but also increase the PSNR improvement in the reconstructed image.