Dinh Trieu Duong

Hybrid Temporal Error Concealment Methods for Block-Based Compressed Video Transmission

Boundary matching algorithm (BMA) and decoder motion vector estimation (DMVE) are two well-known temporal error concealment methods using the matching-based approach. In these two methods, the motion vector of each missing block is estimated by choosing one among candidate motion vectors which minimizes a sum of absolute differences (SAD) between boundary pixels of the corrupted macroblock. In general, the performance of DMVE is better than that of BMA. However, depending on the location or pattern of the corrupted block, BMA produces higher visual quality than DMVE. In this paper, we propose two types of hybrid error concealment methods; switching method and blending method. The switching method chooses one of two results obtained by BMA and DMVE based on the normalized SAD values. In the blending method, the weighted sum of the results concealed by the aforementioned two methods is utilized to improve the performance of error concealment. In order to reduce blocking artifacts further, the modified overlapped-block motion compensation is adaptively applied to the concealed blocks. Simulation results show that the proposed methods outperform other techniques in terms of subjective visual quality as well as PSNR performance.

Power-Aware rate control for mobile multimedia communications

Consumers increasingly demand high quality of service (QoS) for multimedia applications. Rate control scheme is one of the major methods that provide high video quality for mobile multimedia devices over wireless networks. This paper presents an efficient rate-control scheme which estimates the transmission power level of mobile devices, then adaptively adjusts the encoding bit rate according to the estimated power level to minimize overall distortion over sequences of video frames. Experimental results show that the proposed method can efficiently enhance the video quality and provide better peak signal to noise ratio (PSNR) performance than existing TMN8 rate control method.

A novel frame error resilient technique using adaptive redundant picture coding

In this paper, we propose a novel frame error resilient technique which exploits adaptive redundant picture coding in packet loss environment. The proposed algorithm based on redundant picture coding adopted in the H.264/AVC video standard can effectively recover the erroneous video data caused by transmission errors with a small amount of redundant data. In the proposed algorithm, the distortion in the decoded video is estimated using error modeling. Then, adaptive redundant picture coding is performed to minimize the distortion. Experimental results show that the proposed scheme provides better performance than conventional methods in terms of visual quality.

Power-aware rate-control for QoS provisioning over CDMA networks

This paper presents a power-aware rate control method that dynamically adjusts the encoding bit rate according to the receiving power level of mobile stations (MSs) in CDMA network. The proposed rate-control method performs bit allocation at the video frame level using the estimated channel bit rate to minimize the average distortion over wireless video transmission. Experimental results show that the proposed method can significantly enhance the video quality in CDMA networks.

Adaptive GOP bit allocation to provide seamless video streaming in vertical handoff

Vertical handoff is required to offer users the capability of achieving anywhere and anytime internet access with the full service support from interoperability between third generation (3G) and wireless LAN (WLAN) network. However, video data can be lost due to latency caused by vertical handoff. To solve this problem, in this paper, we propose an efficient GOP bit allocation method to provide seamless video streaming in vertical handoff. In the proposed method, the streaming server first predicts the network status by using the wireless channel modeling and then adaptively performs bit allocation for a group of pictures (GOP) to adapt video delivery to vertical handoff scenario. Experimental results show that the proposed method can provide significant improvement to video streaming performance, in terms of users-perceive video quality, and robustness against the latency and packet loss caused by vertical handoff.