Fast Search Mode Research Articles

Complexity reduction for HEVC encoder using one-dimensional filtering based constrained one-bit transform

This paper presents a one-dimensional-filtering-based constrained one-bit transformation (1D-C1BT)-based motion estimation to reduce the complexity of the High Efficiency Video Coding (HEVC) encoder. The proposed 1D-C1BT requires integer arithmetic additions, subtraction and shift operations to convert full resolution video frames to two bit depth 1D-C1BT frames. By embedding the 1D-C1BT in the HEVC encoder, the motion estimation (ME) complexity of the HEVC encoder is greatly reduced in terms of Motion Estimation Time (MET) and total Encoding Time (ET) in uni-prediction and bi-prediction respectively. From the experimental results, it is shown that the 1D-C1BT accompanying full search (FS) and test zonal search (TZS) algorithms greatly reduces MET and ET as compared to the FS and TZS algorithms of the HEVC encoder respectively. To further reduce the intricacy of the HEVC encoder in the fast search mode, star-diamond (SD) search accompanying 1D-C1BT is proposed. The 1D-C1BT accompanying SD further reduces MET and ET with small increment in Bjontegaard Delta Rate and small decrement in Bjontegaard Delta Peak Signal to Noise Ratio, compared to the TZS algorithm of the HEVC encoder. In the FS mode of the HEVC encoder, the proposed 1D-C1BT, accompanying FS, reduces MET by 86.00% and ET by 83.94%, with BD-Rate of 0.1452% and BD-PSNR of 0.2635% in low delay-P main profile. The proposed ME algorithms, 1D-C1BT accompanying full search (FS + 1D-C1BT), 1D-C1BT accompanying test zonal search (TZS + 1D-C1BT) and 1D-C1BT accompanying star diamond search (SD + 1D-C1BT) greatly reduce ME complexity in all the three configurations (low delay-P, low delay-B and random access main profile) of the HEVC encoder.

Complexity reduction of test zonal search for fast motion estimation in uni-prediction of High Efficiency Video Coding

The complexity of motion estimation in the High Efficiency Video Coding (HEVC) standard is very high as it uses a number of prediction block sizes. The test zonal search (TZS) mechanism is used as motion estimation algorithm in the fast search mode of HM encoder, the reference software for HEVC. In this paper, we present schemes for reducing the complexity of the TZS algorithm for uni-prediction in HEVC. The proposed mechanisms help in reducing complexity of grid, raster and refinement search stages of TZS. The performance of the proposed mechanisms is tested independently and also combined in the fast search mode of HM-16.18. The motion estimation time and the number of search points in the combined algorithm are reduced by 68.14% and 77.10% with a BD-rate of 0.30% and a BD-PSNR of $$-0.007$$ dB in comparison with the original fast search mode in the low-delay P main profile. The proposed complexity reduction schemes are compared with those adopted in other recently proposed fast motion estimation algorithms and the performance of the proposed scheme is found to be superior in terms of the reduction in motion estimation time.

Fast search real‐time face recognition based on DCT coefficients distribution

The authors propose an adaptive face recognition algorithm based on the discrete cosine transform (DCT) coefficients approach. For the database's establishment, the face images are pre-processed with colour transform, hair cutting, and background removing to eliminate non-face information. The recognised kernel applied the weights of DCT coefficient distribution with the entire image transformation, to avoid position mismatch and reduce the light effect. The key coefficients of DCT are chosen from the training database by maximum variance. The fast search mode can reject 90% weak candidates with few coefficients to fasten the processing speed. The significant coefficients weighting methods are used to enhance face features. Only using 50 coefficients per picture, the recognition rate can achieve 95% for ORL face database testing. For real-time recognition, camera imaging is processed with algorithms using C-programming based on Windows system. The recognition rate can achieve 95% and the speed is about nine frames per second for real-time recognition in practice.

Complex macrocycle exploration: parallel, heuristic, and constraint-based conformer generation using ForceGen

ForceGen is a template-free, non-stochastic approach for 2D to 3D structure generation and conformational elaboration for small molecules, including both non-macrocycles and macrocycles. For conformational search of non-macrocycles, ForceGen is both faster and more accurate than the best of all tested methods on a very large, independently curated benchmark of 2859 PDB ligands. In this study, the primary results are on macrocycles, including results for 431 unique examples from four separate benchmarks. These include complex peptide and peptide-like cases that can form networks of internal hydrogen bonds. By making use of new physical movements (“flips” of near-linear sub-cycles and explicit formation of hydrogen bonds), ForceGen exhibited statistically significantly better performance for overall RMS deviation from experimental coordinates than all other approaches. The algorithmic approach offers natural parallelization across multiple computing-cores. On a modest multi-core workstation, for all but the most complex macrocycles, median wall-clock times were generally under a minute in fast search mode and under 2 min using thorough search. On the most complex cases (roughly cyclic decapeptides and larger) explicit exploration of likely hydrogen bonding networks yielded marked improvements, but with calculation times increasing to several minutes and in some cases to roughly an hour for fast search. In complex cases, utilization of NMR data to constrain conformational search produces accurate conformational ensembles representative of solution state macrocycle behavior. On macrocycles of typical complexity (up to 21 rotatable macrocyclic and exocyclic bonds), design-focused macrocycle optimization can be practically supported by computational chemistry at interactive time-scales, with conformational ensemble accuracy equaling what is seen with non-macrocyclic ligands. For more complex macrocycles, inclusion of sparse biophysical data is a helpful adjunct to computation.

Complexity reduction for HEVC encoder using multiplication free one-bit transformation

In high-efficiency video coding (HEVC), motion estimation (ME) complexity is high. The ME complexity is greatly reduced by implementing a multiplication free one-bit transform (MF-1BT) in the HEVC encoder. Compared with the other one-bit transforms, the computational load of MF-1BT is less. The implementation of MF-1BT in a HEVC encoder greatly reduces the ME complexity in terms of ME time (MET) and total encoding time (ET). Experimental results show that the MF-1BT along with full search reduces the ME complexity in terms of percentage reduction in MET and ET by 89.03% and 87.53%, respectively, as compared with a conventional full search algorithm with a Bjontegaard delta-rate (BD-rate) of 0.1095% and Bjontegaard delta-peak signal-to-noise ratio (BD-PSNR) of 0.1311% in low delay-P main profile. The performance comparison of test zonal search (TZS) along with MF-1BT is evaluated by comparing it with the TZS algorithm in the fast search mode of the HEVC encoder. Hexagon and diamond search algorithm along with MF-1BT is also proposed in the fast search mode of the HEVC encoder to further reduce the MET and ET compared with the TZS algorithm of the HEVC encoder.

Search range reduction for uni-prediction and bi-prediction in HEVC

The motion estimation block of the high-efficiency video coding (HEVC) standard is highly complex. This paper proposes two algorithms, namely external search range reduction (ESR) and internal search range reduction (ISR) to reduce the motion estimation complexity of HEVC in uni-prediction and bi-prediction both in the fast search mode. The proposed ESR algorithm for uni-prediction motion estimation reduces the search range adaptively for Test Zonal Search (TZS) motion estimation with negligible loss in coding efficiency. The proposed ISR algorithm for uni-prediction, namely ISR-R, limits the search range further in the raster search stage of the TZS algorithm. Moreover, a fast bi-prediction motion estimation algorithm is proposed which includes both ESR and ISR to reduce the motion estimation complexity in bi-prediction. Our algorithms are implemented in the HM-16.6 encoder in the fast search mode. The performance of the proposed algorithms are tested individually and then by combining all the algorithms. When the algorithms are combined, the number of search points and motion estimation time are reduced by 60.58 and 59.58 %, respectively in the fast search mode with a BD-Rate of 0.193 % and BD-PSNR of −0.005 % in the LD-B main profile. The number of search points and motion estimation time are reduced by 59.55 and 57.71 %, respectively in the fast search mode with a BD-Rate of 0.265 % and BD-PSNR of −0.008 % in the RA main profile.

New R-D Optimization Criterion for Fast Mode Decision Algorithms in Video Coding and Transrating

Mode decision has a significant effect on the quality and complexity of video coding. It is even more challenging when generating multiple bitstreams with different bitrates (BRs) in, for example, dynamic adaptive streaming for HTTP or transrating systems. Full search and simplified fast search mode decision (MD) methods either suffer from a high computational complexity or have a negative impact on quality. Furthermore, mode selection in conventional approaches strongly depends on the quantization parameter (QP). Hence, modes that have been selected for high BR compression may not be suitable for low BR when transrating a bitstream. In this paper, we propose a rate-distortion (R-D)-optimized criterion for fast MD algorithms. The proposed cost function, when adopted in different fast MD algorithms, not only improves the R-D performance by up to 6.6% in terms of Bjontegaard delta rate, but also reduces the execution time of the encoder by up to 6.8%. We also show that modes selected by the proposed criterion are less sensitive to changes in BR or QP. As a result, the same modes in an encoded bitstream may be used even after transrating using requantization, resulting in a significant R-D performance improvement of up to 33.3%.

A Multichannel 100 MHz Flash-ADC-System with Fastscan Zero Suppression

A modular multichannel data acquisition system has been developed based on ultrafast (100 MHz) integrated analog-to-digital converters (Flash ADCs). Its basic elements are simple data acquisition modules and controller modules for a flexible and fully programmable configuration. Zero suppression is done in a fast search mode (FASTSCAN) after read in. This system is designed for fast sampling of drift chamber signals in order to measure the drift time, the coordinate along the wire (by charge division), the charge (dE/dx) of the signal and to provide a good double track resolution.