EARLY RESYNCHRONIZATION AND ERROR CONCEALMENT I OF VIDEO TRANSMITTED OVER WIRELESS CHANNELS

Abstract

The demand for video services over wireless channels is a new trend in the user requirements nowadays. Wireless channels are error prone mediums where the bandwidth is low, the error rate is high and the error occurs in bursts. Extensive research efforts are done to increase the perceived video quality as using post­ processing techniques at decoder side, known as Error Concealment (EC) techniques. These techniques utilize both spatial and temporal redundancy in the video sequence so that error effect is concealed depending on the scene complexity. The objective is not to make any changes on the encoder side so that we focus our attention on the decoder side and the post processing operations to increase its proper operation in the presence of error. Due to the nature of variable length coding used in MPEG-2 standard, an error can

cause an unresolved situation where decoding is halted and restarted at the next slice header causing the loss of a MacroBlock or a whole slice. Early resynchronization tries to minimize the effect of error by decoding some information that is discarded by usual MPEG-2 decoders. Current algorithms suffer from very high computational complexity making them not suitable for real time playback.