A multistage mode decision method to reduce the complexity of Intra prediction in H.264/JVT is proposed in this work. The rate-distortion optimized (RDO) mode decision is adopted by H.264 to achieve the optimal coding...
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ISBN:
(纸本)0819452114
A multistage mode decision method to reduce the complexity of Intra prediction in H.264/JVT is proposed in this work. The rate-distortion optimized (RDO) mode decision is adopted by H.264 to achieve the optimal coding gain at the cost of a very high computational complexity. Our research goal is to reduce the complexity of intra prediction without significant RD performance loss. The proposed fast intra prediction algorithm uses two features, i.e. the sum of absolute residual coefficients (SATD) and the sum of absolute gradients (SAG), and a simplified RDO method to determine the best mode for 4x4 blocks. It incorporates an early termination mechanism at various intermediate decision steps to avoid unnecessary computations when a good decision can be made at an earlier stage. It is demonstrated by experimental results that the proposed scheme performs approximately 10 to 30 times faster than the current RDO mode decision (JM7.3a) with little degradation in the coding gain.
We investigate the encoding speed improvement for H.264 with a special focus on fast intra-prediction mode selection in this work. It is possible to adopt the rate-distortion (RD) optimized mode in H.264 to maximize t...
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ISBN:
(纸本)081945124X
We investigate the encoding speed improvement for H.264 with a special focus on fast intra-prediction mode selection in this work. It is possible to adopt the rate-distortion (RD) optimized mode in H.264 to maximize the coding gain at the cost of a very high computational complexity. To reduce the complexity associated with the intra-prediction mode selection, we propose a two-step fast algorithm. In the first step, we make a course-level decision to split all possible candidate modes into two groups: the group to be examined further and the group to be ignored. The sizes of these two groups are adaptively determined based on the block activities. Then, in the second step, we focus on the group of interest, and consider an RD model for final decision-making. It is demonstrated by experiment results that the proposed scheme performs 5 to 7 time faster than the current H.264 encoder (JM5.0c) with little degradation in the coding gain.
We present a unified approach to the construction of multidimensional trellis codes that have small constellation expansion ratio (CER) and small peak-to-average power ratio (PAR) and hence are of high bandwidth effic...
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We present a unified approach to the construction of multidimensional trellis codes that have small constellation expansion ratio (CER) and small peak-to-average power ratio (PAR) and hence are of high bandwidth efficiency. In the approach, we extend Wei's construction to dimensionalities other than a power of two and propose a low-complexityencoder. We also present a general partition technique that gives geometrically uniform partitions with a good distance profile. The proposed method can generate many good codes including previously reported Ungerboeck codes, Gallager-Calderbank-Sloane codes, and Wei codes with quadrature amplitude modulation signals. Some newly discovered six-dimensional trellis codes are compared with these known codes on their CER, PAR, effective coding gain, and encoder/decoder complexities.
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