Kwan-Woong Song

Error concealment of multi-view video sequences using inter-view and intra-view correlations

An efficient error concealment algorithm for multi-view video sequences is proposed in this work. First, we develop three concealment modes: temporal bilateral error concealment (TBEC), inter-view bilateral error concealment (IBEC), and multi-hypothesis error concealment (MHEC). TBEC and IBEC, respectively, exploit intra-view and inter-view correlations in multi-view video sequences to reconstruct an erroneous block. MHEC finds a few candidate blocks based on the block matching principle and combines them for the concealment. We then propose a mode selection scheme, which chooses one of the three modes adaptively to provide reliable and accurate concealment results. Simulation results demonstrate that the proposed algorithm can protect the quality of reconstructed videos effectively even in severe error conditions.

Broad-band erbium-doped fiber amplifier with double-pass configuration

We demonstrate a broad-band silica-based erbium-doped fiber amplifier (EDFA) with double-pass configuration. The signal gain and noise figure are obtained more than 24 dB and less than 6 dB, respectively, for 1526-1562 nm and 1569-1605 nm. The same signal gain can be achieved with 53% less pump power and 45% shorter erbium-doped fiber length, compared to a conventional parallel type EDFA. Furthermore, the noise figure and power conversion efficiency are improved for the wavelength range.

1-fiber WDM self-healing ring with bidirectional optical add/drop multiplexers

We propose a 1-fiber bidirectional WDM self-healing ring that has bidirectional optical add/drop multiplexers. A simple fault detection method is proposed, and no signal degradation due to in-band crosstalk is demonstrated in the failure state. The power penalty of the ring transmission was less than 1 dB at a BER 10/sup -12/ in the normal and failure state.

Error concealment techniques for multi-view video sequences

In this work, we investigate error patterns in compressed multi-view video signals and propose three error concealment algorithms, which can hide the effects of transmission errors efficiently. The proposed algorithms conceal a lost block by choosing and combining the best candidate blocks in the temporally adjacent frames or the inter-view frames at the same time instance. Simulation results demonstrate that the proposed algorithms effectively protect the quality of reconstructed videos against transmission errors.

Error Concealment of H.264/AVC Video Frames for Mobile Video Broadcasting

An efficient frame error concealment (EC) algorithm for H.264 video is proposed in this work. The proposed algorithm temporally conceals a lost frame by combining several pixels or several motion vectors using an overlapping window. The proposed algorithm requires a low computational complexity, but provides better performance than the conventional frame error concealment methods. Therefore, the proposed algorithm is suitable for mobile video broadcasting applications.

Multi-view video coding with view interpolation prediction for 2D camera arrays

An efficient compression algorithm for multi-view video sequences, which are captured by two-dimensional (2D) camera arrays, is proposed in this work. First, we propose a novel prediction structure, called three-dimensional hierarchical B prediction (3DHBP), which can efficiently reduce horizontal inter-view redundancies, vertical inter-view redundancies, and temporal redundancies in multi-view videos. Second, we develop a view interpolation scheme based on the bilateral disparity estimation. The interpolation scheme yields high quality view frames by adapting disparity estimation and compensation procedures using the information in neighboring frames. Simulation results demonstrate that the proposed multi-view video coding algorithm provides significantly better rate-distortion (R-D) performance than the conventional algorithm, by employing the 3DHBP structure and using interpolated view frames as additional reference frames.

Efficient Multi-Hypothesis Error Concealment Technique for H.264

An efficient multi-hypothesis error concealment algorithm for H.264 video is proposed in this work. The proposed algorithm temporally conceals a lost block by combining several hypothesis blocks in the previous frame. We investigate the error recovery performance according to the number of hypotheses and the weighting coefficients. Simulation results demonstrate that the proposed algorithm provides better performance than the conventional error concealment algorithm, although the additional complexity requirement is negligible.

Efficient stereo video coding based on frame skipping for real-time mobile applications

An efficient stereo video coding algorithm based on frame skipping is proposed for real-time mobile applications in this work. Based on the binocular suppression theory, the proposed algorithm skips a selected set of frames to save the encoding complexity and the transmission bit rate. At the decoder side, we reconstruct those skipped frames faithfully using the advanced bilateral interpolation method. Extensive simulation results demonstrate that the proposed algorithm provides better PSNR performances than the conventional stereo coding algorithm, while achieving realtime encoding and decoding.

Virtual view synthesis using multi-view video sequences

A virtual view synthesis algorithm using multi-view video sequences, which inherits the advantages of both the forward warping and the inverse warping, is proposed in this work. First, we use the inverse warping to synthesize a virtual view without holes from the nearest two views. Second, we detect occluded regions in the synthesized view based on the uniqueness constraint. Then, we refine the occluded regions using the information in the farther views based on the forward warping technique. Simulation results demonstrate that the proposed algorithm provides significantly higher PSNR performances than the conventional inverse warping scheme.

Adaptive rate control for real-time video streaming over the mobile WiMAX

To achieve high video quality for real-time video streaming over the mobile WiMAX network, it is necessary to adaptively adjust the target bit rate of the video encoder based on verified network status. Since it is difficult to verify network congestion using only PHY-layer parameters, this paper proposes an algorithm for verifying network status by using a MAC-layer parameter implying PHY-layer information and then correspondingly adjusting the target bit rate. The results show that the proposed algorithm achieves a video quality 0.7 to 6.3 dB higher than that achieved with fixed target bit rates over the mobile WiMAX network.