Fast Inter-Mode Decision Based on Rate-Distortion Cost Characteristics.
ABSTRACT In this paper, a new fast mode decision (FMD) algorithm is proposed for the state-of-the-art video coding standard H.264/AVC.
Firstly, based on Rate-Distortion (RD) cost characteristics, all inter modes are classified into two groups, one is Skip mode
(including both Skip and Direct modes) and all the other inter modes are called non-Skip modes. In order to select the best
mode for coding a Macroblock (MB), minimum RD costs of these two mode groups are predicted respectively. Then for Skip mode,
an early Skip mode detection scheme is proposed; for non-Skip modes, a three-stage scheme is developed to speed up the mode
decision process. Experimental results demonstrate that the proposed algorithm has good robustness in coding efficiency with
different Quantization parameters (Qps) and various video sequences and is able to achieve about 54% time saving on average
while with negligible degradation in Peak-Signal-to-Noise-Ratio (PSNR) and acceptable increase in bit rate.
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ABSTRACT: This paper proposes an efficient algorithm for fast mode decision in H.264/advanced video coding by adaptively predicting the optimal mode for each macroblock (MB) to be coded. Firstly, encoding modes are projected as points onto a 2-D map, and an optimal 2-D point of the MB to be coded is predicted based on the encoding information of spatial-temporal neighboring blocks. Then, a priority-based mode candidate list with a descending order to be the best mode is constructed based on the optimal 2-D point. Finally, mode decision is performed according to the priority-based mode candidate list in the checking order, from the most important mode to the least one, with early termination conditions. Extensive experimental results demonstrate that the proposed algorithm is superior to three recent fast mode decision algorithms, with the entire encoding time being reduced by about 60% for quarter common intermediate format/common intermediate format/standard-definition sequences on average and the rate distortion performance being kept almost intact.IEEE Transactions on Circuits and Systems for Video Technology 06/2010; · 1.82 Impact Factor
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ABSTRACT: The new video coding standard, H.264/MPEG-4 AVC, uses variable block sizes ranging from 4×4 to 16×16 in interframe coding. This new feature has achieved significant coding gain compared to coding a macroblock (MB) using fixed block size. However, this feature results in extremely high computational complexity when brute force rate distortion optimization (RDO) algorithm is used. This paper proposes a fast intermode decision algorithm to decide the best mode in intercoding. It makes use of the spatial homogeneity and the temporal stationarity characteristics of video objects. Specifically, spatial homogeneity of a MB is decided based on the MB's edge intensity, and temporal stationarity is decided by the difference of the current MB and it colocated counterpart in the reference frame. Based on the homogeneity and stationarity of the video objects, only a small number of intermodes are selected in the RDO process. The experimental results show that the fast intermode decision algorithm is able to reduce on the average 30% encoding time, with a negligible peak signal-to-noise ratio loss of 0.03 dB or, equivalently, a bit rate increment of 0.6%.IEEE Transactions on Circuits and Systems for Video Technology 08/2005; · 1.82 Impact Factor
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ABSTRACT: In the new video coding standard H.264/AVC, motion estimation (ME) is allowed to search multiple reference frames. Therefore, the required computation is highly increased, and it is in proportion to the number of searched reference frames. However, the reduction in prediction residues is mostly dependent on the nature of sequences, not on the number of searched frames. Sometimes the prediction residues can be greatly reduced, but frequently a lot of computation is wasted without achieving any better coding performance. In this paper, we propose a context-based adaptive method to speed up the multiple reference frames ME. Statistical analysis is first applied to the available information for each macroblock (MB) after intra-prediction and inter-prediction from the previous frame. Context-based adaptive criteria are then derived to determine whether it is necessary to search more reference frames. The reference frame selection criteria are related to selected MB modes, inter-prediction residues, intra-prediction residues, motion vectors of subpartitioned blocks, and quantization parameters. Many available standard video sequences are tested as examples. The simulation results show that the proposed algorithm can maintain competitively the same video quality as exhaustive search of multiple reference frames. Meanwhile, 76 %-96 % of computation for searching unnecessary reference frames can be avoided. Moreover, our fast reference frame selection is orthogonal to conventional fast block matching algorithms, and they can be easily combined to achieve further efficient implementations.IEEE Transactions on Circuits and Systems for Video Technology 05/2006; · 1.82 Impact Factor