In this paper, a new fast encoding algorithm based on an efficient motion estimation (ME) process is proposed to accelerate the encoding speed of the scalable video coding standard. Through analysis of the ME process performed in the enhancement layer, we discovered that there are redundant MEs and some MEs can simply be unified at the fully overlapped search range (FOSR). In order to make the unified ME more efficient, we theoretically derive a skip criterion to determine whether the computation of rate-distortion cost can be omitted. In the proposed algorithm, the unnecessary MEs are removed and a unified ME with the skip criterion is applied in the FOSR. Simulation results show that the proposed algorithm achieves computational savings of approximately 46% without coding performance degradation when compared with the original SVC encoder.

In this paper, we propose an improved coeff_token variable-length decoding (VLD) method in the CAVLC decoder. The number of memory accesses is one of the significant issues in the applications such as DMB and videophone services, where the low-power consumption and high-speed operation are required. In order to cut down the heavy memory accesses, a new fast VLD method is developed through the careful examination of the codewords in variable-length code tables (VLCTs). The simulation results show that the proposed method achieves an approximately 60% memory access saving without video-quality degradation, compared to the existing fast coeff-token VLD method.

A large amount of memory accesses are required for CAVLC decoding in the H.264/AVC baseline profile. It is an important issue for low-power implementation of mobile video applications because the memory access function results in considerable power consumption. We have found some distinctive features in the variable-length code table (VLCT) of total_zeros element through a careful analysis of the codeword. Based on these features, efficient memory architecture is designed and new decoding method is developed in this paper. The simulation results show that the new decoding with the proposed memory architecture achieves an approximately 80∼90% memory access saving compared to conventional decoding.

A new total_zeros decoding method based on efficient memory architecture for variable-length code tables (VLCTs) is proposed in this paper. In general, a large amount of memory accesses are required for context-based adaptive variable-length coding (CAVLC) decoding in the H.264/AVC standard. It is an important issue for low-power implementation of mobile video applications because the memory access function results in considerable power consumption. Some distinctive features in the VLCTs of the total_ zeros have been found through a careful analysis of the codewords. Efficient memory architecture and an advanced decoding are developed in order to remove redundant memory access. The simulation results show that the proposed method achieves an approximately 80%-90% memory access saving, compared with conventional decoding.

In general, a large amount of memory accesses are required for context-based adaptive variable-length coding decoding in H.264/AVC standard. It is a serious problem for applications such as videophone and digital multimedia broadcasting services because of the considerable power consumption of the memory access function. In order to reduce the memory access, we carefully examined the codewords in variable-length code tables (VLCTs) of the coeff-token and found some distinctive features from the structure of codewords. Based on the features, a new coeff-token decoding method with an efficient memory organization is proposed in this paper. The simulation results show that the proposed algorithm achieves an approximately 95% memory access saving without video-quality degradation, compared with conventional decoding

In this paper, we propose a computation reduction method for RDO mode decision in H.264/AVC. The distortion required for RDO mode decision has been shown to be equivalent to the total energy of quantization error. A statistical model of the quantization error for H.264/AVC was developed in order to approximate the distortion. In the proposed method, the reconstruction processes including quantization, inverse quantization, and inverse DCT are not needed. Simulation results demonstrate that the distortion is efficiently approximated with a quality and bit-rate comparable to conventional H.264/AVC.

The bit portion for motion-vector (MV) information becomes significant in very-low bitrate video coding as texture coding has been improved. Especially, the existing methods, such as minimum bitrate prediction (MBP)-based coding, do not work well for slow-moving video sequences, which are popular in video conferencing and videophone applications. It is because the characteristics of the video sequences are not fully exploited for the MV encoding. In this paper, we propose a new hybrid encoding scheme for MV. A new parameter called a skip rate (SR) is defined for estimating the degree of the locality for the MV difference in the proposed scheme. In addition, we suggest a joint coding with a new single codeword combined with the horizontal and vertical codewords. Either the joint coding or the MBP-based coding is determined by the SR. The simulation results show that the proposed scheme enhances the coding performance for various video sequences without additional memory.

An improved algorithm for the early detection of all-zero blocks in H.264 video encoding is proposed in this paper. Based on the theoretical analyzes for the integer transform and quantization in H.264, we derive a sufficient condition under which each quantized coefficient becomes zero. And then, a more precise sufficient condition is proposed by modifying the calculation order of the sum of absolute difference obtained in the motion estimation. The simulation results show that the proposed algorithm achieves approximately an 11%-36% computational saving without video-quality degradation, compared to the conventional method.

In this paper, a new early detection algorithm for all-zero DCT blocks in H.264 video encoding is proposed. We have analyzed the properties of the DCT and quantization in H.264. These analyses show that a great reduction in the number of calculations can be achieved by investigating the individual conditions for the frequency components of (1,1), (1,3), (3,1), and (3,3). Based on these facts, a more precise sufficient condition is proposed by modifying the calculation order of the minimum SAD. Simulation results show that the redundant DCT and Q are efficiently removed without video-quality degradation.

An improved fast full-search algorithm for motion estimation is proposed. The computational process of the sum of absolute difference and the multilevel successive elimination algorithm (MSEA) are theoretically analysed. Based on these analyzes, a new detection criterion and an estimation of the starting level are proposed in order to reduce the computations required for judging invalid candidate blocks. The simulation results show that the proposed algorithm achieves a computational timesaving of about 40% compared with the MSEA.

It is well known that a lot of computations are required for motion estimation in video encoding. Recently, the multilevel successive elimination algorithm (MSEA) has been proposed to reduce the computational complexity of block matching for motion estimation without degradation of estimation accuracy. In the MSEA, the block matching is hierarchically carried out and the invalid candidate block is successively eliminated. In this paper, we propose an improved MSEA based on a new efficient decision condition. The number of the calculations to eliminate the invalid block can be reduced by the new efficient decision condition in the proposed algorithm. The simulation results show that the proposed algorithm achieves about 30-40% computational saving as compared with the MSEA.

In this correspondence, we show that the number of iterations required for the convergence of the fractal image decoding algorithm can be reduced by selecting a suitable initial image. We consider fractal decoding to have two components, namely, "DC" and "AC". Our initial image is an approximation of the attractor of DC decoding, which is a good estimation of the "range-averaged" image, i.e., the image obtained by replacing all pixel intensities in a given block by the mean value of the block. From the simulation, it is demonstrated that the decoding speed is greatly improved.