Fast Bit Rate Estimation for Mode Decision of H.264/AVC

IEEE Transactions on Circuits and Systems for Video Technology, 2006

In video coders, the optimal coding mode decision for each coding block can be achieved by exhaustively calculating the rate-distortion cost, which simultaneously considers the distortion performance and the coding bit consumption of all possible modes. The best mode is chosen from the one with the minimum Lagrange cost. To avoid the expensive computation of Lagrange costs, in this paper, we propose transform-domain bit-rate estimation and distortion measures, based on quantized and inverse quantized integer transform coefficients, for the inter-mode decision in H.264/AVC coders. With the proposed scheme, entropy coding, inverse transform, and pixel-reconstructions are not required in the process. With ignorable degradation in coding performance, simulations demonstrate that the proposed estimation method achieves about 40% reduced computation time of rate-distortion cost for the inter-mode decision and saves about 17% total encoding time while combining with fast motion estimation and fast mode decision algorithms.

IEEE Transactions on Circuits and Systems for Video Technology, 2007

Signal Processing: Image Communication, 2009

The H.264/AVC standard yields higher coding efficiency rates than other video coding standards. This is because it uses the rate-distortion optimization (RDO) technique, which selects the optimal coding mode and a reference frame for each macroblock (MB). In order to achieve this, the encoder has to encode a given block by exhaustively using all kinds of combinations (including different intra and inter-prediction modes). As a result, the computational complexity of video coding in H.264/AVC is extremely high. In this paper, two fast intra-/inter-mode-decision algorithms are proposed to reduce the complexity of the encoder. Both of these algorithms are based on the inter-frame correlation among adjacent pictures. For the fast intra-mode-decision, we used the intra-mode of the mostcorrelated MB at the reference frame to encode the current MB and the stationary property of the current MB was used for the fast inter-mode-decision. The simulation results show that the proposed algorithms significantly reduced the computational complexity with a negligible loss of PSNR and a slight increase in bitrate.

2005 IEEE International Conference on Multimedia and Expo

In a video coder, the optimal coding mode decision for each coding block could be achieved by exhaustively calculating the Lagrange cost (which includes the coding distortion plus the Lagrange parameter times the coding bit consumption) of all possible modes. The best mode can then be chosen as the one with the minimum Lagrange cost. To speed up the computationally intensive Lagrange cost computation, in this paper, we propose transform-domain bit-rate estimation and distortion measures for the inter-mode decision in H.264/AVC coders. With the proposed scheme, entropy coding, inverse DCT, and pixel-reconstructions are not required in the process. Simulation results show that the proposed estimation method is accurate for the inter-mode decision and about 46.42% time reduction can be achieved.

Effective Video Coding for Multimedia Applications, 2011

IEEE Transactions on Multimedia, 2000

The H.264 video coding standard significantly outperforms previous standards in terms of coding efficiency. However, this comes as a cost of extremely high computational complexity due to mode decision where variable block size Motion Estimation (ME) is employed. In this paper, we propose an efficient algorithm to jointly optimize mode decision and ME. A theoretical analysis is performed to study the sufficient condition to detect all-zero blocks in H.264, and thus adaptive thresholds are derived to early terminate mode decision and ME. Besides the aforementioned early termination technique, the proposed algorithm also introduces temporal-spatial checking, thresholds based prediction and monotonic error surface based prediction methods to skip checking unnecessary modes. Experimental results demonstrate that the proposed algorithm can significantly reduce the computational complexity of H.264 encoding while maintaining almost the same Rate Distortion (RD) performance as the original encoder.

2006 10th IEEE Singapore International Conference on Communication Systems, 2006

H.264/AVC, the latest video standard, adopts rate-distortion optimization (RDO) technique to obtain the best intra-and interprediction, while maximizing visual quality and minimizing the required bitrate. However, the full RD cost calculation for all intra-prediction modes, the exhaustive searches for finding optimal motion vectors for all block sizes, and the multiple references frame procedure considerably increase its computational complexity with the allowed number of prediction modes. In order to reduce the complexity, here we propose a new approach for both inter-and intra-mode decisions, that takes into account the two effective parameters, image content type and the quantization parameter. The proposed fast intra-prediction mode selection strategy uses some observations on the interior and the exterior MB properties to select a subset of candidate modes at different quantization parameters. Also, the fast inter-prediction mode decision approach uses split/merge procedure based on correlation of motion vectors and motion details of video objects. Also, here we use a context-based adaptive method to speed up the multiple reference frames motion estimation that is based on inter-and intra-prediction residues and quantization parameters. As such, only a subset of inter-and intra-modes is chosen for RDO calculation. Experimental results show that the proposed algorithm, reduces the total encoding cost with negligible loss in PSNR and a slightly increase in the required bitrate, when compared to RDO and other fast algorithms reported in the literature.

Multimedia, 2010

2008

One of the new features in the H.264/AVC encoder is the use of Lagrangian Rate-Distortion Optimization (RDO) method during mode decision at the macroblock level. The RDO technique has been employed in H.264/AVC for intra prediction mode selection to achieve better coding efficiency. But the computation complexity of mode decision algorithm is extremely high. To reduce the complexity of mode decision, we propose an efficient and fast 4x4 intra prediction mode selection scheme. The proposed method reduces the candidate of the prediction modes based on the Sum of Absolute Transformed Difference (SATD) between the original block and the intra predicted block. Rank of each mode is obtained based on the SATD value. The candidate modes are further reduced by using the combination of rank and most probable mode. Simulation results demonstrate that the proposed mode decision method reduces about 95 % of mode decision time of intra coding with ignorable degradation of coding performance.

2004

The emerging H.264-AVC video coding standard aims to significantly improve compression performance compared to all existing video coding standards. In order to achieve this, a robust rate-distortion optimization (RDO) technique is employed to select the best coding mode and reference frame for each macroblock. As a result, the complexity and computation load increase drastically. This paper presents a fast mode decision algorithm for H.264 intra prediction based on local edge information. Prior to intra prediction, an edge map is created and a local edge direction histogram is then established for each sub-block. Based on the distribution of the edge direction histogram, only a small part of intra prediction modes are chosen for RDO calculation. Experimental results show that the last intra mode decision scheme increases the speed of intra coding significantly with negligible loss of PSNR.