Error concealment in MPEG video streams over ATM networks

摘要

When transmitting compressed video over a data network, one has tondeal with how channel errors affect the decoding process. This isnparticularly a problem with data loss or erasures. In this paper wendescribe techniques to address this problem in the context ofnasynchronous transfer mode (ATM) networks. Our techniques can benextended to other types of data networks such as wireless networks. InnATM networks channel errors or congestion cause data to be dropped,nwhich results in the loss of entire macroblocks when MPEG video isntransmitted. In order to reconstruct the missing data, the location ofnthese macroblocks must be known. We describe a technique for packing ATMncells with compressed data, whereby the location of missing macroblocksnin the encoded video stream can be found. This technique also permitsnthe proper decoding of correctly received macroblocks, and thus preventsnthe loss of ATM cells from affecting the decoding process. The packingnstrategy can also be used for wireless or other types of data networks.nWe also describe spatial and temporal techniques for the recovery ofnlost macroblocks. In particular, we develop several optimal estimationntechniques for the reconstruction of missing macroblocks that containnboth spatial and temporal information using a Markov random field model.nWe further describe a sub-optimal estimation technique that can benimplemented in real time