MPEG-7 Based Spatial Shape Concealment Difficulty

In a digital video communication, the encoder can play a very important role on what can be achieved at the decoder side in terms of error processing. To behave in the best way, it is important that the encoder try to foresee the difficulties that the decoder will face dealing with errors and work to help it, notably in the most critical moments. In particular, if the encoder evaluates how difficult certain errors are to conceal, it will be able to better decide the amount of error resilience overhead to be used and where. This evaluation at the encoder may be done by considering the video data being encoded and the coding scheme being used. When object-based video coding schemes such as the one specified by the MPEG-4 standard are considered, channel errors can affect both the shape and texture data, which can be concealed using spatial and/or temporal techniques. In this paper, a spatial shape concealment difficulty measure based on an MPEG-7 descriptor is proposed, with the target to allow the encoder to control the amount of intra-coding refreshment to be used for the shape information in order to improve the concealment performance at the decoder.