Temporal and spatial error concealment techniques for hierarchical MPEG-2 video codec

The MPEG-2 source coding algorithm is very sensitive to the channel disturbances. For instance a single bit error in the bitstream will cause a high degradation of picture quality due to error propagation. Hence, for picture replenishment error concealment techniques (ECTs) may be required at the receiver. The aim of the article is to study different ECTs for MPEG-2 hierarchical coded pictures applied for terrestrial broadcasting. For the base layer different temporal and spatial ECTs are investigated. Two temporal ECTs are considered: a simple temporal error concealment (EC) and a temporal EC with motion compensation. The latter method provides the best results in inter coded pictures (where motion vectors exist). For the intra coded pictures, where no motion information exists, two spatial interpolation techniques are considered. The main problem for spatial EC in MPEG-2 coded pictures is that only the top and the bottom macroblock can be used for interpolation, since one error in the bitstream causes one damaged horizontal stripe of macroblocks in the picture. Different ECTs for the upper layer of hierarchical coded pictures are also investigated. The possibility of upsampling the base layer for concealing the upper layer made by spatial scalability gives best results