New Hybrid Error Concealment for Digital Compressed Video
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New Hybrid Error Concealment for Digital Compressed Video Ofer Hadar Communication Systems Engineering Department, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel Email: [email protected]
Merav Huber Electrical and Computer Engineering Department, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel Email: [email protected]
Revital Huber Electrical and Computer Engineering Department, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel Email: [email protected]
Shlomo Greenberg Communication Systems Engineering Department, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel Email: [email protected] Received 2 August 2004; Revised 26 December 2004; Recommended for Publication by Reha Civanlar Transmission of a compressed video signal over a lossy communication network exposes the information to losses and errors, which leads to significant visible errors in the reconstructed frames at the decoder side. In this paper we present a new hybrid error concealment algorithm for compressed video sequences, based on temporal and spatial concealment methods. We describe spatial and temporal techniques for the recovery of lost blocks. In particular, we develop postprocessing techniques for the reconstruction of missing or damaged macroblocks. A new decision support tree is developed to efficiently choose the best appropriate error concealment method, according to the spatial and temporal characteristics of the sequence. The proposed algorithm is compared to three error concealment methods: spatial, temporal, and a previous hybrid approach using different noise levels. The results are evaluated using four quality measures. We show that our error concealment scheme outperforms all the other three methods for all the tested video sequences. Keywords and phrases: error concealment, spatial/temporal/hybrid error concealment, video coding, MPEG-2, decision tree, multimedia/video communication.
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INTRODUCTION
The demand for transmitting compressed video over data network increases as bandwidth and storage of computer networks grow. Signal loss occurring in physical communication channels is unavoidable. During data transmission of packets over the Internet, packets may be dropped or damaged, due to channel errors, congestion, and buffer limitation. Moreover, the data may arrive too late to be used in real-time applications. These errors fall into two categories: (1) bit stream errors caused by direct signal loss of some or the whole compressed packet of a coded MB, and result in the loss of a single block, a group of blocks or macroblocks, or the whole respective slice information; (2) propagation errors
caused in P- and B-frames uniquely by the additional use of motion-compensated time information for their reconstruction at the decoder side. Errors in previously decoded reference frames propagate to their dependent frames in the decoding order. In the case of transmission of compressed video sequences such as MPEG-2, this loss may be devastating and result in a completely damaged
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