A Robust Error Concealment Algorithm in Wireless Networks

IEEE Transactions on Consumer Electronics, 2008

A compressed video bitstream is extremely sensitive to errors when it is transmitted via networks with bursty packet loss such as 3G and mobile WiMAX. Error concealment techniques have been used to improve the recovered picture quality in cases in which parts of the coded picture are not available at the decoder for reconstruction. However, most conventional error concealment methods show low image reconstruction performance due to unavailable motion information about image blocks during burst packet loss, and require high energy consumption to find the best error concealment method in the receiver. The proposed error concealment aware error resilient streaming video system has an intelligent error concealment selector. The method recommends the best error concealment method per macroblock, by additionally transmitting its error concealment selection codes to the decoder. The streaming client conceals the corrupted MB via the chosen error concealment method, with low energy consumption, even when the frame loss is bursty. The experimental results show that the system is highly effective, in terms of the video quality and energy consumption, at the cost of a slight overhead for transmitted bit streams. 1

In this paper we describe two error-recovery approaches for MPEG encoded video over ATM networks. The first approach aims at reconstructing each lost pixel by spatial interpolation from the nearest undamaged pixels. The second approach recovers lost macroblocks by minimizing intersample variations within each block and across its boundaries. Moreover, a new technique for packing ATM cells with compressed data is also proposed.

2003

Compressed video sequences are very vulnerable to channel disturbances when they are transmitted through the burst-packet-loss networks such as a wireless channel. An effective solution for packet loss is to perform concealment at the receiver. Most of the spatial and/or temporal concealment methods estimate the true motion vector (MV) associated with a missing block by using the MVs of adjacent blocks. However, these methods can not conceal effectively the missing blocks, since the neighboring blocks can be easily lost by the burst packet losses destroying a large area of coded video. In this paper, we present a robust error concealment method of estimating the true MV of the missing block by using the bidirectional motion tracking technique within neighboring frames of a damaged frame. This motion tracking technique uses the linear trajectory feature of the image block in the forward and backward prediction directions. Experimental results show that the proposed algorithm has superior subjective and objective video quality than conventional error concealment methods in the burstpacket-loss environments .

2002

Video transport over error-prone channels may result in loss or erroneous decoding of the video data. Error concealment is an effective mechanism to reconstruct the video data. In this paper, we review error-concealment methods and introduce a new framework, which we refer to as second-generation error concealment. All the error-concealment methods reconstruct the lost video data by making use of certain a priori knowledge about the video content. First-generation error concealment builds such a priori in a heuristic manner. The proposed second-generation error concealment builds the a priori by modeling the statistics of the video content explicitly, typically in the region of interest (ROI). Context-based models are trained with the correctly received video data and then used to replenish the lost video data. Trained models capture the statistics of the video content and thus reconstruct the lost video data better than reconstruction by heuristics. A new dynamic model 'updating principal components' (UPC) is proposed as a model for second-generation error concealment. UPC can be applied to pixel values to conceal loss of pixel data. In addition, UPC can be applied to motion vectors, which results in 'updating eigenflows' (U-Eigenflow), to conceal loss of motion vectors. With UPC applied to both pixel values and motion vectors, hybrid temporal/spatial error concealment can be achieved. The proposed second-generation error-concealment method provides superior performances to first-generation error-concealment methods.