In this letter, fast intra mode decision algorithms for HEVC Screen Contents Coding (SCC) are proposed. HEVC SCC has been developed to efficiently code mixed contents consisting of natural video, graphics, and texts. Comparing to HEVC version 1, the SCC encoding complexity significantly increases due to the newly added intra block copy mode. To reduce the heavy encoding complexity, the evaluation orders of multiple intra modes are rearranged and several early termination schemes based on intermediate coding information are developed. Based on our evaluation, it is found that the proposed method can achieve encoding time reduction of 13∼30% with marginal coding gain or loss, compared with HEVC SCC test model 2.0 in all intra (AI) case.

This paper proposes a fast mode decision technique for intra prediction of High Efficiency Video Coding (HEVC) based on a reliability metric for motion vectors (RMMV). Since such a decision problem can be regarded as a kind of pattern classification, an efficient classifier is required for the reduction of computation complexity. This paper employs the RMMV as a classifier because the RMMV can efficiently categorize image blocks into flat(uniform), active, and edge blocks, and can estimate the direction of an edge block as well. A local search for angular modes is introduced to further speed up the decision process. An experiment shows the advantage of our technique over other techniques.

In this paper, a specified hardware architecture of the Fast Mode Decision (FMD) algorithms presented by our previous work is proposed. This architecture is designed as an embedded mode dispatch module. On the basis of this module, some unnecessary modes can be skipped or the mode decision process can be terminated in advanced. In order to maintain a higher compatibility, the FMD algorithms are unitedly designed as an unique module that can be easily embedded into a common video codec for H.265/HEVC. The input and output interfaces between the proposed module and other parts of the codec are designed based on simple but effective protocol. Hardware synthesis results on FPGA demonstrate that the proposed architecture achieves a maximum frequency of about 193 MHz with less than 1% of the total resources consumed. Moreover, the proposed module can improve the overall throughput.

High efficiency video coding (HEVC) is a video compression standard that outperforms the predecessor H.264/AVC by doubling the compression efficiency. To enhance the intra prediction accuracy, 35 intra prediction modes were used in the prediction units (PUs), with partition sizes ranging from 4 × 4 to 64 × 64 in HEVC. However, the manifold prediction modes dramatically increase the encoding complexity. This paper proposes a fast mode- and depth-decision algorithm based on edge detection and reconfiguration to alleviate the large computational complexity in intra prediction with trivial degradation in accuracy. For mode decision, we propose pixel gradient statistics (PGS) and mode refinement (MR). PGS uses pixel gradient information to assist in selecting the prediction mode after rough mode decision (RMD). MR uses the neighboring mode information to select the best PU mode (BPM). For depth decision, we propose a partition reconfiguration algorithm to replace the original partitioning order with a more reasonable structure, by using the smoothness of the coding unit as a criterion in deciding the prediction depth. Smoothness detection is based on the PGS result. Experiment results show that the proposed method saves about 41.50% of the original processing time with little degradation (BD bitrate increased by 0.66% and BDPSNR decreased by 0.060dB) in the coding gain.

The emerging high-efficiency video coding (HEVC) standard attempts to improve the coding efficiency by a factor of two over H.264/AVC through the use of new compression tools such as various block sizes with multiple directions. Although multiple-directional predictions are among the features contributing to the improved compression efficiency, its high computational complexity keeps it from being used widely. This paper presents an algorithm to skip backward and bi-directional predictions when merge or forward prediction modes are likely to be determined as the best mode. The proposed algorithm takes advantage of the fact that there is a cost relationship among multi-directional predictions and that the results of backward and bi-directional predictions are therefore predictable before the actual operations. After merge and forward predictions, if the expected results of backward and bi-directional predictions are worse than the results up to that point, then additional backward and bi-directional predictions to search for more accurate motion vectors are not performed. A simulation shows that the encoding time is reduced by about 15.18% with a marginal degradation in compression efficiency.

This letter proposes a pipelined architecture with prediction mode scheduling for high efficiency video coding (HEVC). An increased number of intra prediction modes in HEVC have introduced a new technique, named rough mode decision (RMD). This development, however, means that pipeline architectures for H.264 cannot be used in HEVC. The proposed scheme executes the RMD and the rate-distortion optimization (RDO) process simultaneously by grouping the intra prediction modes and changing the candidate selection method of the RMD algorithm. The proposed scheme reduces execution cycle by up to 26% with negligible coding loss.

Video coding plays an important role in human life especially in communications. H.264/AVC is a prominent video coding standard that has been used in a variety of applications due to its high efficiency comes from several new coding techniques. However, the extremely high encoding complexity hinders itself from real-time applications. This paper presents a new encoding algorithm that makes use of particle swarm optimization (PSO) to train discriminant functions for classification based fast mode decision. Experimental results show that the proposed algorithm can successfully reduce encoding time at the expense of negligible quality degradation and bitrate increases.

The emerging High Efficiency Video Coding (HEVC) standard attempts to improve the coding efficiency by a factor of two over H.264/AVC through the use of new compression tools with high computational complexity. Although multipledirectional prediction is one of the features contributing to the improved compression efficiency, the computational complexity for prediction increases significantly. This paper presents an early uni-directional prediction decision algorithm. The proposed algorithm takes advantage of the property of HEVC that it supports a deep quad-tree block structure. Statistical observation shows that the correlation of prediction direction among different blocks which share same area is very high. Based on this observation, the mode of the current block is determined early according to the mode of upper blocks. Bi-directional prediction is not performed when the upper block is encoded as the uni-directional prediction mode. A simulation shows that it reduces ME operation time by about 22.7% with a marginal drop in compression efficiency.

A direct inter-mode selection algorithm for P-frames in fast homogeneous H.264/AVC bit-rate reduction transcoding is proposed in this paper. To achieve the direct inter-mode selection, we firstly develop a low-complexity distortion estimation method for fast transcoding, in which the distortion is directly calculated from the decoded residual together with the reference frames. We also present a linear estimation method to approximate the coding rate. With the estimated distortion and rate, the rate-distortion cost can be easily computed in the transcoder. In our algorithm, a method based on the normalized rate difference of P-frames (RP) is used to detect the high motion scene. To achieve fast transcoding, only for the P-frames with RP larger than a threshold, the rate-distortion optimized (RDO) mode decision is performed; meanwhile, the average cost of each inter-mode (ACM) is calculated. Then for the subsequent frames transcoding, the optimal coding mode can be directly selected using the estimated cost and the ACM threshold. Experiments show that the proposed method can significantly simplify the complex RDO mode decision, and achieve transcoding time reductions of up to 62% with small loss of rate-distortion performance.

Different encoding modes for variable block size are available in the H.264/AVC standard in order to offer better coding quality. However, this also introduces huge computation time due to the exhaustive check for all modes. In this paper, a fast spatial DIRECT mode decision method for profiles supporting B frame encoding (main profile, high profile, etc.) in H.264/AVC is proposed. Statistical analysis on multiple video sequences is carried out, and the strong relationship of mode selection and rate-distortion (RD) cost between the current DIRECT macroblock (MB) and the co-located MBs is observed. With the check of mode condition, predicted RD cost threshold and dynamic parameter update model, the complex mode decision process can be terminated at an early stage even for small QP cases. Simulation results demonstrate the proposed method can achieve much better performance than the original exhaustive rate-distortion optimization (RDO) based mode decision algorithm by reducing up to 56.8% of encoding time for IBPBP picture group and up to 67.8% of encoding time for IBBPBBP picture group while incurring only negligible bit increment and quality degradation.

The H.264/AVC standard achieves significantly high coding efficiency if multiple block size Motion Estimation is adopted. However, the complexity of Motion Estimation and DCT is dramatically increased as a result. In previous work we propose an early mode decision algorithm to control the complexity, based on all-zero-blocks detection in 1616 size. In this paper, we improve the algorithm. Firstly, we propose to detect all-zero blocks in 1616, 88 and 44 sizes to simplify the course of mode decision. Secondly, we define the thresholds which are used to terminate motion estimation and mode decision in advance for these sizes. Last, we present the whole proposed algorithm. Experiments show that about 77% encoding time and 85% motion estimation time can be saved on average, which is better than state-of-the-art approaches.

In this letter, we present a simple but efficient intra prediction mode decision for H.264/AVC. Based on our investigation, the DC mode appears to be the superior prediction mode among the various candidates. We propose an intra-mode decision algorithm where the DC mode is chosen as a candidate for the best prediction mode. By experimental results, on average, the proposed algorithm significantly saves 81.905% of the entire encoding time compared to the H.264 reference software; besides, it reduces negligible peak signal-to-noise ratio (PSNR) values and slightly increases bitrates.

The rate-distortion optimization (RDO) method in the H.264/AVC encoder is an informative technology that improves the coding efficiency, but increases the computational complexity. In this letter, a fast Intra mode decision algorithm using DCT (Discrete Cosine Transform) coefficients distribution is proposed to reduce the H.264 encoder complexity. The proposed method reduces the encoder complexity on average 63.44%, while the coding efficiency is slightly decreased compared with the H.264/AVC encoder.

Scalable video coding (SVC) was standardized as an extension of H.264/AVC by the JVT (Joint Video Team) in Nov. 2007. The biggest feature of SVC is multi-layered coding where two or more video sequences are compressed into a single bit-stream. This letter proposes a fast block mode decision algorithm in spatial enhancement layer of SVC. The proposed algorithm achieves early decision by limiting the number of candidate modes for block with certain characteristic called same motion vector block (SMVB). Our proposed method reduces the complexity, in terms of encoding time by up to 66.17%. Nevertheless, it shows negligible PSNR degradation by only up to 0.16 dB and increases the bit-rate by only up to 0.64%, respectively.

Since multiview video coding (MVC) based on H.264/AVC uses a prediction scheme exploiting inter-view correlation among multiview video, MVC encoder compresses multiple views more efficiently than simulcast H.264/AVC encoder. However, in case that the number of views to be encoded increases in MVC, the total encoding time will be greatly increased. To reduce computational complexity in MVC, a fast mode decision using both Macroblock-based region segmentation information and global disparity vector among views is proposed to reduce the encoding time. The proposed method achieves on the average 1.5 2.9 reduction of the total encoding time with the PSNR (Peak Signal-to-Noise Ratio) degradation of about 0.05 dB.

One fast inter mode decision algorithm is proposed in this paper. The whole algorithm is divided into two stages. In the pre-stage, by exploiting spatial and temporal information of encoded macrobocks (MBs), a skip mode early detection scheme is proposed. The homogeneity of current MB is also analyzed to filter out small inter modes in this stage. Secondly, during the block matching stage, a motion feature based inter mode decision scheme is introduced by analyzing the motion vector predictor's accuracy, the block overlapping situation and the smoothness of SAD (sum of absolute difference) value. Moreover, the rate distortion cost is checked in an early stage and we set some constraints to speed up the whole decision flow. Experiments show that our algorithm can achieve a speed up factor of up to 53.4% for sequences with different motion type. The overall bit increment and quality degradation is negligible compared with existing works.

A new H.264 fast inter-mode decision algorithm based on coded block patterns is presented. Compared to the exhaustive mode search, the proposed method achieves an average 57 % reduction in computation time with negligible degradation in visual quality. The speed and rate-distortion performance is comparable to known fast algorithms that involve more elaborate mechanisms.

Intra coding in H.264/AVC has significantly enhanced video compression efficiency. However, computation complexity increases by the rate-distortion (RD) based mode decision. This paper proposes a novel fast mode decision algorithm in H.264/AVC intra prediction and its VLSI architecture. A novel edge-detection pattern is proposed and both edge-detection technique and spatial mode prediction technique are combined together to reduce the number of intra 44 candidate modes from 9 to an average of 2.50. VLSI architecture of intra mode decision module is designed with TSMC 0.18 µm CMOS technology. The maximum frequency of 285 MHz is achieved and 13.1k NAND gates are required. High frequency, efficient processing cycle reduction and small area make this design to be an excellent accelerator for HDTV 1080p@30 fps real time encoder.

A fast intra-mode decision algorithm is proposed on the basis of an inter-mode block type for inter-frames (P-slices). Each macroblock (MB) type has its own intra prediction modes (I16MB and 88 chroma: 4 modes, I4MB and I8MB: 9 modes). This procedure creates a large computational complexity in addition to the inter mode decision procedure. In most cases, there is a high correlation between the best inter-mode block type and the direction of the texture edge or object boundary. Therefore, only a small number of intra-prediction modes are chosen to determine the best intra mode based on this correlation. We experimentally verify that the proposed scheme can significantly improve the speed of the overall encoding time with a negligible loss of image quality and a minimal bit increase. The average loss in PSNR was -0.0120.036 dB and the bit increment was approximately -0.1940.751%.

The coexistence of MPEG-2 and its powerful successor H.264/AVC has created a huge need for MPEG-2/H.264 video transcoding. However, a traditional transcoder where an MPEG-2 decoder is simply cascaded to an H.264 encoder requires huge computational power due to the adoption of a complicated rate-distortion based mode decision process in H.264. This paper proposes a 2-D Sobel filter based motion vector domain method and a DCT domain method to measure macroblock complexity and realize content-based H.264 candidate mode decision. A new local edge based fast INTRA prediction mode decision method is also adopted to boost the encoding efficiency. Simulation results confirm that with the proposed methods the computational burden of a traditional transcoder can be reduced by 20%30% with only a negligible bit-rate increase for a wide range of video sequences.