Fast 4*4 intra-prediction based on the most probable mode in H.264/AVC

Abstract

Abstract:In this paper, we analyze that the best mode for intraprediction can be changed by the RD cost related with the bit to signal the prediction mode according to whether the most probable mode (MPM) and the prediction mode are same or not. With this understanding, we propose a fast 4 × 4 intra-prediction based on the MPM in the H.264/AVC. This algorithm uses a defined RD cost including the minimum bit to signal the prediction modes excluded the MPM as a threshold. Experimental results show that the proposed algorithm is capable of reducing the overall encoding time by 36% and the overall intra-prediction time by 47% compared to the full search, with negligible loss of quality. Keywords: H.264, intra prediction, mode probable mode Classification: Integrated circuits

Fast feature-based mode decision for 4×4 intra prediction in H.264/AVC

“…A lot of efforts have been made to speed up the computation during the coding process [4][5][6][7][8][9][10][11][12][13][14][15][16]. For intra prediction in H.264/AVC, many fast algorithms have been proposed.…”

“…Some fast algorithms reduce the RDO complexity by filtering impossible block type for luma components [6][7]11]. Most of fast algorithms reduce the complexity based on the candidate modes selection [8][9][10][11][12][13][14][15][16]. By preprocessing, only small numbers of prediction modes are chosen as candidate modes for RDO calculation instead of all possible modes in the full search algorithm.…”

“…In addition to edge detection technique above, candidate modes can also be determined based on SAD and (or) SATD feature of prediction modes introduced in [12][13][14][15][16]. SAD is the sum of absolute difference between the original block and the predicted block, and SATD is the sum of absolute transformed difference.…”

“…In addition, because natural video sequences are highly spatially correlated, intra prediction modes for neighboring 4 × 4 blocks are highly correlated. The most probable mode of the current block is achieved according to the mode of upper or left block already encoded, and it has a higher chance of being selected as the prediction mode [11,[15][16][17]. In [15], the candidate modes are further reduced from nine to one or two based on the combination of SATD and most probable mode.…”

“…For SAD-based and SATD-based methods, although the SAD or SATD computations are a little more complicated than preprocessing computation of edge-based methods, the number of candidate modes is smaller than four in general; especially only one or two modes are picked up in good cases. In [16], La et al also proposed a fast 4 × 4 intra prediction mode decision algorithm based on the most probable mode. A defined RD cost is used as a threshold for fast intra prediction.…”