We propose a specific channel encoder to support error concealment of mutually independent source codec parameters. To introduce artificial dependencies a recursive non-systematic convolutional (RNSC) code is applied which exhibits a code rate near r = 1. The channel encoder may be considered as a smearing filter. A TURBO-like exploitation of artificial dependencies and of residual source redundancy according to the iterative source-channel decoding (ISCD) algorithm permits step-wise quality improvements. Previously known error concealment techniques are outperformed in the most interesting range of channel conditions.