FIR/IIR cascade approximating H.264/AVC interpolation filter

Interpolation implemented as an FIR filter followed by an IIR filter is proposed for video coding. Being good approximation to the interpolation filter of the H.264/AVC video coding standard, it has lower complexity measure. It is shown that the proposed filter cascade has minimal achievable round-off error for fixed-point arithmetic. Specific boundary conditions for IIR part that make this filtering affordable for small prediction blocks are provided. The proposed cascade can be used as an interpolation filter for fast motion estimation in hybrid video codecs. Comparison to known short FIR filter used for motion estimation part for H.264/AVC video encoder is provided. The proposed cascade may be used as a self-consistent interpolation filter.