A novel motion estimation algorithm for arbitrarily shaped video coding

In this paper, we present a fast motion estimation algorithm for arbitrarily shaped video coding in MPEG-4. This novel algorithm takes advantage of our new discovery about the close relation between the best matching block and its shape information-alpha plane. Without any additional padding computation, this new motion estimation algorithm computes the sum of absolute difference (SAD) between two alpha planes rather than the pixels´ intensities. Compared with the full search block-matching algorithm (recommended in the MPEG-4 standard), the proposed algorithm achieves an impressive speed-up ratio with very minor quality degradation and little bit-count increase. Extensive simulations are provided in this paper to demonstrate this fact.