Early Termination and Pipelining for Hardware Implementation of Fast H.264 Intraprediction Targeting Mobile HD Applications

H.264/AVC adopts aggressive compression algorithms at the cost of increased computational complexity. To speed up the H.264/AVC intraframe coding, this paper proposes two novel techniques: early termination and pipelined execution. In P slices, intra 4×4 and 16×16 predictions are early terminated with the threshold determined by the cost of motion estimation. In I slices, intra 4×4 prediction is early terminated with the threshold derived from intra 16×16 prediction. The threshold function is chosen as a monotonically decreasing linear function with its optimal coefficients determined by experiments. For the pipelined execution of 4×4 intrapredictions, the processing order of 4×4 blocks is changed to reduce the dependencies between consecutively processed blocks. In I slices, computation for 4×4 intraprediction is reduced by 19 percent with the proposed early termination. In P slices, computations for 4×4 and 16×16 intrapredictions are reduced by more than 81 and 91 percents, respectively. The pipelined execution reduces the computation time by 41 percent. In spite of the speed-up by the proposed methods, degradation in rate-distortion performance is negligible. The proposed pipelined execution is integrated with other H.264/AVC hardware accelerators and fabricated as an SoC using Dongbu 0.13 μm technology.