Error control for H.263 video transmission over wireless channels

We consider ways to combat the error effects when transmitting H.263 video over a wireless channel. The error control measures consist of two `layers,' namely, that of the coded bitstream and of the video information. At the bitstream layer, we employ error-resilient entropy coding (EREC), with pseudo-random block interleaving, to reduce the error propagation in decoding of variable-length codewords. At the information layer, we employ a DC recovery scheme to conceal the effects of corrupted DC coefficients. Corrupted motion vectors are detected and corrected using a motion-vector pairing technique in the encoder and a corresponding motion-vector checking and recovery algorithm in the decoder. By these methods, corrupted strips in the images caused by loss of synchronization are avoided. The annoying `green/pink block artifacts' caused by erroneous DC coefficients and the effects of incorrect motion compensation caused by corrupted motion vectors are also reduced.