  An optimization technique based on an adapted combination of simulated
annealing (SA) and tabu search (TS) is presented. This method aims at finding
near-optimal unequal error protection (UEP) application-layer FEC code
configurations. This approach is intended to smartly protect audio and video
transmission over IP networks when hard time restrictions apply. The considered
code is a UEP version of the widely-used Pro-MPEG COP3 codes enabling the use
of several matrices of dissimilar size and thus of unequal recovery capability.
Finding the optimal configuration frequently requires the evaluation of a large
solution space. So, to fulfill the imposed constraints, SA is adapted to the
specifics of the scenario. In particular, the annealing schedule is conditioned
by the real-time restrictions. Furthermore, solution neighborhood structures
are determined by a proposed definition of distance between protection
configurations, which, jointly with TS, conditions the selection of candidate
solutions. Experimental results show a significantly improved performance of
the optimization process, which invariably fulfills imposed timing constraints,
at the expense of a very low distortion increase, when compared to using
exhaustive search. These results allow the use of UEP Pro-MPEG COP3 codes for
protecting video and audio transmission, which distinctly outperforms the
standard code in a wide range of scenarios.
