Prediction mode reordering and IDCT direction control for fast intra 8×8 prediction

This paper presents a novel architecture of intra 8×8 prediction for a high profile H.264 intra frame encoder. Intra 8×8 prediction consists of prediction and reconstruction phases and two phases are performed in a pipeline manner. In the 2-stage pipelined schedule, bubbles between prediction and reconstruction phases are the main bottleneck for fast 8×8 prediction. To reduce bubbles, prediction mode reordering and Inverse Discrete Cosine Transform (IDCT) direction control schemes are proposed. The proposed schemes reduce 115 cycles of bubbles to perform intra 8×8 prediction for a macroblock and achieve a 24.5% speed-up.