VLSI Architecture Design of Fractional Motion Estimation for H.264/AVC
The H.264/AVC Fractional Motion Estimation (FME) with rate-distortion constrained mode decision can improve the rate-distortion efficiency by 26 dB in peak signal-to-noise ratio. However, it comes with considerable computation complexity. Acceleration by dedicated hardware is a must for real-time applications. The main difficulty for FME hardware implementation is parallel processing under the constraint of the sequential flow and data dependency. We analyze seven inter-correlative loops extracted from FME procedure and provide decomposing methodologies to obtain efficient projection in hardware implementation. Two techniques, 44 block decomposition and efficiently vertical scheduling, are proposed to reuse data among the variable block size and to improve the hardware utilization. Besides, advanced architectures are designed to efficiently integrate the 6-taps 2D finite impulse response, residue generation, and 44 Hadamard transform into a fully pipelined architecture. This design is finally implemented and integrated into an H.264/AVC single chip encoder that supports realtime encoding of 720480 30fps video with four reference frames at 81MHz operation frequency with 405 K logic gates (41.9% area of the encoder).
vlsi architecture motion estimation h.264/avc video coding