Novel CAVLC design for secondary SP-frame

The quantized DCT coefficients of secondary SP-frame are different from conventional P-frame statistically. Therefore, the context-based adaptive variable length coder (CAVLC) designed in H.264 is not suitable for secondary SP-frame. A novel entropy coding approach based on CAVLC is designed for secondary SP-frame according to the special characteristic. The approach selects better VLC table for the level coding of nonzero coefficients by modeling the data fluctuation in each block. Moreover, tables of coding nonzero coefficients and trailingones are also redesigned. Simulation results show that the proposed approach can save 2.04% bits in average compared with H.264/AVC.