Improved performance H.263 under erroneous transmission conditions

The authors present an algorithm for limiting the propagation of errors in an H.263 video bit stream subject to channel degradation. The frequency of occurrence of INTRA coded frames (I-frame) is increased to thwart the temporal dependency of predicted frames (P-frame). The proposed algorithm ensures that all R-bit length INTRADC coefficients of I-frames are received by inducing a change in their order of transmission. To combat the effect of channel corruption on INTRADC coefficients, a half rate convolutional coder is used. The synchronisation is protected by sending synch words at fixed-length intervals within the bit stream. Results showed that the proposed algorithm improved the quality of service (QoS) of the video coder on both the subjective and objective scales, even when similar target bit-rates are considered