Most video coding standards, including MPEG-4, use variable length
codes to encode the discrete cosine transform (DCT) coefficients
of intra frames and inter frames, and the motion vector
information. Although variable length codes can achieve good
compression, they are very sensitive to channel errors, especially
in wireless channels, which are characterized by bursty errors.
Joint source-channel decoding (JSCD) is emerging as a potential
alternative to traditional error resilience methods for dealing
with this sensitivity to channel errors. This paper describes one
such JSCD for the reliable transmission of MPEG-4 video over
wireless channels. We apply the maximum a posteriori probability based JSCD developed for first order Markov sources to both inter and intra coded macroblocks. Experiments indicate that the proposed decoder gives significant improvements (9 dB in some cases) for MPEG-4 video with error resilience at various channel error rates.