The invention is related to methods and apparatus that encode redundant motion
vectors for predictive-coded visual object planes (P-VOPs) to increase the robustness
of transmitted video signals. One embodiment provides the redundant motion vectors
in a user data video packet of an MPEG-4 compliant bitstream, which thereby allows
the enhanced bitstream to remain compliant with MPEG-4 syntax and backwards compatible
with MPEG-4 decoders. The enhanced bitstreams allow a video decoder to display
a video with a better picture and relatively less error and error propagation when
portions of the bitstream are disturbed or corrupted by interference, delays, and
the like.