Spiral intra macroblock refresh with motion vector restriction for low bit-rate video telephony over a 3G network

A method to limit the effect of error propagation in low bit-rate error resilient video coding has been proposed and implemented on a 3G prototype videophone. In conventional methods, the effect of the bit-stream error does not vanish rapidly since the refreshed macroblocks are affected by the errors in the unrefreshed macroblocks. To overcome this ineffectiveness, two techniques are used; one is motion vector restriction that limits the error propagation, and the other is the spiral intra macroblock refresh that minimizes coding efficiency degradation caused by the motion vector restriction. Further, the latter technique concentrates on the center area in the screen, where the subjective preference is closely related. Experiments show that the proposed method removes the effect of the error more rapidly than the conventional methods.