Frame loss error concealment for SVC

Scalable video coding (SVC), as the Scalable Extension of H.264/AVC, is an ongoing international video coding standard designed for network adaptive or device adaptive applications and also offers high coding efficiency. However, packet losses often occur over unreliable networks even for base layer of SVC and have severe impact on the playback quality of compressed video. Until now, no literature has discussed error concealment support for standard SVC bit-stream. In this paper, we provide robust and effective error concealment techniques for SVC with spatial scalability. Experimental results showed that the proposed methods provide substantial improvement, both subjectively and objectively, without a significant complexity overhead.

An error resilient scheme for H.264 video coding based on distortion estimated mode decision and nearest neighbor error concealment

Although H.264 video coding standard provides several error resilience tools, the damage caused by error propagation may still be tremendous. This work is aimed at developing a robust and standard-compliant error resilient coding scheme for H.264and uses techniques of mode decision, data hiding, and error concealment to reduce the damage from error propagation. This paper proposes a system with two error resilience techniques that can improve the robustness of H.264 in noisy channels. The first technique is Nearest Neighbor motion compensated Error Concealment (NNEC) that chooses the nearest neighbors in the reference frames for error concealment. The second technique is Distortion Estimated Mode Decision (DEMD) that selects an optimal mode based on stochastically distorted frames. Observed simulation results showed that the rate-distortion performances of the proposed algorithms are better than those of the compared algorithms.

Error concealment in pixel based Wyner-Ziv video coding

In the Wyner-Ziv(WZ) video coding paradigm, a virtual correlation channel is assumed between the quantized source and the side information(SI) at the decoder, and channel coding is applied to achieve compression. In this paper, errors caused by the virtual correlation channel are addressed and an error concealment approach is proposed for pixel-based WZ video coding. In the approach, errors after decoding are classified into two types. Type 1 errors are caused by residual bit errors after channel decoding, while type 2 errors are due to low quality of SI in part of a frame which causes SI not lying within the quantization bin of a decoded quantized pixel value. Two separate strategies are respectively designed to detect and conceal the two types of errors. Simulations are carried out and results are presented to demonstrate the effectiveness of the proposed approach.

Analysis and application of error concealment tools in AVS-M decoder

Audio Video coding Standard (AVS) is the latest audio and video coding standard of China. AVS Part 7 (also known as AVS-M) targets mobility applications where error concealment is of great importance. This paper first briefly introduces the general concept of error concealment. Then two error concealment schemes are proposed and implemented on AVS-M decoder under different test conditions. Simulation results of the schemes and suggestions on how to use these tools are also provided.

Content-adaptive robust error concealment for packet-lossy H.264 video streaming

In this paper, we present a spatio-temporal post-processing error concealment (EC) algorithm designed initially for a H.264 video-streaming scheme over packet-lossy networks. It aims at optimizing the subjective quality of the restored video under the constraints of low delay and computational complexity, which are critical to real-time applications and portable devices having limited resources. Specifically, it takes into consideration the physical property of motion field in order to achieve more meaningful perceptual video quality, in addition to the improved objective PSNR. Further, a simple bilinear spatial interpolation approach is combined with the improved boundary-match (B-M) based temporal EC approach according to texture and motion activity analysis. Finally, we propose a low complexity temporal EC method based on motion vector interpolation as a replacement of the B-M based approach in the scheme under low-computation requirement, or as a complement to further improve the scheme's performance in applications having enough computation resources. Extensive experiments demonstrated that the proposal features not only better reconstruction, objectively and subjectively, than JM benchmark, but also robustness to different video sequences.

Temporal Shape Error Concealment for Video Objects

A novel temporal shape error concealment technique is proposed, which can he used in the context of object-based video coding schemes. In order to reduce the effect of the shape variations of a video object, the curvature scale space （CSS） technique is adopted to extract features, and then these features are used for boundary matching between the current frame and the previous frame. Because the temporal, spatial and sta- tistical video contour information are all considered, the proposed method can find the optimal matching, which is used to replace the damaged contours. The simulation results show that the proposed algorithm achieves better subjective, objective qualities and higher efficiency than those previously developed methods.

A NOVEL TEMPORAL ERROR CONCEALMENT METHOD BASED ON FUZZY REASONING FOR H.264

In this paper,a fuzzy reasoning based temporal error concealment method is proposed. The basic temporal error concealment is implemented by estimating Motion Vector (MV) of the lost MacroBlock (MB) from its neighboring MVs. Which MV is the most proper one is evaluated by some criteria. Generally,two criteria are widely used,namely Side Match Distortion (SMD) and Sum of Absolute Difference (SAD) of corresponding MV. However,each criterion could only partly describe the status of lost block. To accomplish the judgement more accurately,the two measures are considered together. Thus a refined measure based on fuzzy reasoning is adopted to balance the effects of SMD and SAD. Terms SMD and SAD are regarded as fuzzy input and the term ‘similarity’ as output to complete fuzzy reasoning. Result of fuzzy reasoning represents how the tested MV is similar to the original one. And k-means clustering technique is performed to define the membership function of input fuzzy sets adaptively. According to the experimental results,the concealment based on new measure achieves better performance.

Whole Frame Error Concealment with Refined Motion Extrapolation and Prescription at Encoder for H.264/AVC

Packet losses usually result in frame losses in low bit rate video streaming over error prone networks. The whole frame error concealment （EC） algorithm is then necessary for the decoder to improve the video quality. A refined bidirectional motion vector extrapolation was developed to improve the motion vector estimation precision by alleviating the effect of overlapped and hole regions with an adaptive overlapped block motion compensation to reduce block artifacts. A prescription-based framework was then developed to improve the error concealment at the encoder side. Simulations show that the EC algorithm at the decoder side outperforms the existing methods by 2-8 dB. Moreover, the prescription-based framework at the encoder side provides further peak signal to noise ratio improvement.

An Error Concealment Approach Based on H.263 Video Decoding in Pixel Domain

The video bit stream coded by H.263 recommendation is vulnerable to channel errors. For coded information, bit errors could result in error propagation, loss of synchronization and severe data loss. All of these will lead to the descent of image qualities in the end. In this paper, in order to solve this problem, we present a receiver based error concealment algorithm that uses information in pixel domain to detect errors and resynchronization, identify the location of the affected blocks and estimate erroneous data. The concealment algorithm is kept simple, no additional bit rate is required, and no modification is necessary to an existing encoder, so the real time decoding and concealment are possible. Computer emulation results show that the image quality after error concealment is significantly improved.

Time-delay signature concealment of polarizationresolved chaos outputs in vertical-cavity surface-emitting lasers with variable-polarization filtered optical feedback

Through employing permutation entropy and the self-correlation function, the time-delay signature （TDS） of a vertical-cavity surface-emitting laser （VCSEL） with variable-polarization filtered optical feedback （VPFOF） is evaluated theoretically. The work shows that the feedback rate η, polarizer angle Op, and filter bandwidth A have an obvious influence on the TDS. The evolution maps of the TDS in parameter space （η, A） and （ηθp） are simulated for searching the chaos with weak TDS. Furthermore, compared with a VCSEL with polarization-preserved filtered optical feedback and a VCSEL with variable-polarization mirror optical feedback, this VPFOF-VCSEL shows superiority in TDS suppression.

One Case of Primary Thrombocythemia with Concealed Hypokalemia Complicated by Acute Myocardial Infarction

Medical history summary: Male, 47 years old, was admitted to the hospital due to “dizziness accompanied by chest tightness and pain for more than 8 days”. One week ago, the patient experienced chest tightness, chest pain accompanied by profuse sweating for 3 hours and underwent emergency percutaneous coronary intervention (PCI) at a local hospital. The procedure revealed left main stem occlusion with subsequent left main stem to left anterior descending artery percutaneous transluminal coronary angioplasty (PTCA). After the procedure, the patient experienced hemodynamic instability, recurrent ventricular fibrillation, and critical condition, thus transferred to our hospital for further treatment. Symptoms and signs: The patient is in a comatose state, unresponsive to stimuli, with bilateral dilated pupils measuring 2.0 mm, exhibiting reduced sensitivity to light reflex, and recurrent fever. Coarse breath sounds can be heard in both lungs, with audible moist rales. Irregular breathing pattern is observed, and heart sounds vary in intensity. No pathological murmurs are auscultated in any valve auscultation area. Diagnostic methods: Coronary angiography results at the local hospital showed complete occlusion of the left main stem, and left main stem to left anterior descending artery percutaneous transluminal coronary angioplasty (PTCA) was performed. However, the distal guidewire did not pass through. After admission, blood tests showed a Troponin T level of 1.44 ng/ml and a Myoglobin level of 312 ng/ml. The platelet count was 1390 × 109/L. Von Willebrand factor (vWF) activity was measured at 201.9%. Bone marrow aspiration biopsy showed active bone marrow proliferation and platelet clustering. The peripheral blood smear also showed platelet clustering. JAK-2 gene testing was positive, confirming the diagnosis of primary thrombocytosis. Treatment methods: The patient is assisted with mechanical ventilation and intra-aortic balloon counterpulsation to improve coronary blood flow. Electrolyte levels are closely monitored, especially maintaining plasma potassium levels between 4.0 and 4.5 mmol/l. Hydroxyurea 500 mg is administered for platelet reduction. Anticoagulants and antiplatelet agents are used rationally to prevent further infarction or bleeding. Antiarrhythmic, lipid-lowering, gastroprotective, hepatoprotective, and heart failure treatment are also provided. Clinical outcome: The family members chose to withdraw treatment and signed for discharge due to a combination of reasons, including economic constraints and uncertainty about the prognosis due to the long disease course. Acute myocardial infarction has gradually become one of the leading causes of death in our country. As a “green channel” disease, corresponding diagnostic and treatment protocols have been established in China, and significant progress has been made in emergency care. There are strict regulations for the time taken from the catheterization lab to the cardiac intensive care unit, and standardized treatments are provided to patients once they enter the intensive care unit. Research results show that the incidence of acute myocardial infarction in patients with primary thrombocythemia within 10 years is 9.4%. This type of disease is rare and difficult to cure, posing significant challenges to medical and nursing professionals. In order to benefit future patients, we have documented individual cases of treatment and nursing care for these patients. The research results show that these patients exhibit resistance to traditional oral anticoagulant drugs and require alternative anticoagulants. Additionally, there are significant differences in serum and plasma potassium levels among patients. Therefore, when making clinical diagnoses, it is necessary to carefully distinguish between the two. Particularly, nursing personnel should possess dialectical thinking when supplementing potassium levels in patients in order to reduce the incidence of malignant arrhythmias and mortality rates.

Edge-Oriented Spatial Interpolation for Error Concealment of Consecutive Blocks

This paper proposes a low-complexity spatial-domain error concealment （EC） algorithm for recovering consecutive blocks error in still images or intra-coded （I） frames of video sequences. The proposed algorithm works with the following steps. Firstly the Sobel operator is performed on the top and bottom adjacent pixels to detect the most probable edge direction of current block area. After that one-dimensional （1-D） matching is used on the available block boundaries. Displacement between edge direction candidate and most probable edge direction is taken into consideration as an important factor to improve stability of 1-D boundary matching. Then the corrupted pixels are recovered by linear weighting interpolation along the estimated edge direction. Finally the interpolated values are merged to get last recovered picture. Simulation results demonstrate that the proposed algorithms obtain good subjective quality and higher PSNR than the methods in literatures for most images.

Multi-Level Error Detection and Concealment Algorithm to Improve Speech Quality in GSM Full Rate Speech Codecs

Digital mobile telecommunication systems, such as the global system for mobile （GSM） system, want to further improve speech communication quality without changing the channel encoders and decoders. Speech quality is most affected by residual bit errors in received speech frames. Conventional methods use binary decision strategies for error detection and concealment in frames. This paper presents a multi-level error detection and concealment algorithm for GSM full rate speech codec systems. The algorithm uses multi-source knowledge to detect and conceal speech frame errors at the frame, parameter, and even bit levels. Tests show that most corrupted frames can be appropriately concealed by this algorithm, resulting in MOS gains of more than 50% for real-world data tests.

Robust spatio-temporal error concealment for packet- lossy H.264 video transmission

In this article, a spatio-temporal post-processing error concealment algorithm designed initially for a H.264 video-streaming scheme over packet-lossy networks has been presented. It aims at optimizing subjective quality of restored video and the conventional objective metric, peak signal-to-noise ratio （PSNR）, as well, under the constraints of low delay and computational complexity, which are critical to real-time applications and portable devices having limited resources. Specifically, it takes into consideration physical property of motion to achieve more meaningful perceptual video quality. Further, a content-adaptive bilinear spatial interpolation approach and a temporal error concealment approach are combined under a unified boundary match criterion based on texture and motion activity analysis. Extensive experiments have demonstrated that the proposal not only result in better reconstruction, objectively and subjectively, than the reference software model benchmark, but also results in better robustness to different video sequences.

A Novel Frame Error Concealment Scheme Based on Gain Control for TCX Audio Codec

A novel frame error concealment scheme is proposed to improve the decoded audio quality of the receiver for transform coded excitation（TCX）audio codec.This scheme,which is a gain control approach based on the stability of linear predictive coding（LPC）filter,predicts the lost frames by utilizing the linear spectrum frequency and different continuous attenuation factor of different kinds of lost frames.Signal noise ratio（SNR）test and multiple stimuli with hidden reference and anchor（MUSHRA）test are conducted to evaluate the performance of this approach in adaptive multi-rate wideband plus（AMR-WB＋）audio codec.Compared with the original frame error concealment scheme,our scheme achieves better audio recovery quality in AMR-WB＋audio codec.

Waterproofing Technology of Underground Subway Tunnels

The waterproof construction of subway tunnels is a crucial and challenging aspect of subway tunnel engineering.Mastering excellent waterproof construction technology is essential to ensure that the construction meets design requirements and guarantees the safe operation of subway lines.This paper focuses on discussing waterproof construction technology for subway station tunnels.By analyzing the main methods and techniques of underground tunnel construction,as well as the key techniques and difficulties of waterproofing construction,this paper examines the waterproofing construction project of Guangzhou Metro Culture Park Station as a case study.It analyzes the methods,quality management practices,and safety management strategies applied in the project.This paper serves as a reference for tunnel engineering design and construction units in our country,offering insights into effective waterproof construction techniques for subway tunnels.

Dual Attribute Adversarial Camouflage toward camouflaged object detection

The object detectors can precisely detect the camouflaged object beyond human perception.The investigations reveal that the CNNs-based(Convolution Neural Networks)detectors are vulnerable to adversarial attacks.Some works can fool detectors by crafting the adversarial camouflage attached to the object,leading to wrong prediction.It is hard for military operations to utilize the existing adversarial camouflage due to its conspicuous appearance.Motivated by this,this paper proposes the Dual Attribute Adversarial Camouflage(DAAC)for evading the detection by both detectors and humans.Generating DAAC includes two steps:(1)Extracting features from a specific type of scene to generate individual soldier digital camouflage;(2)Attaching the adversarial patch with scene features constraint to the individual soldier digital camouflage to generate the adversarial attribute of DAAC.The visual effects of the individual soldier digital camouflage and the adversarial patch will be improved after integrating with the scene features.Experiment results show that objects camouflaged by DAAC are well integrated with background and achieve visual concealment while remaining effective in fooling object detectors,thus evading the detections by both detectors and humans in the digital domain.This work can serve as the reference for crafting the adversarial camouflage in the physical world.

A Derivative Matrix-Based Covert Communication Method in Blockchain

The data in the blockchain cannot be tampered with and the users are anonymous,which enables the blockchain to be a natural carrier for covert communication.However,the existing methods of covert communication in blockchain suffer from the predefined channel structure,the capacity of a single transaction is not high,and the fixed transaction behaviors will lower the concealment of the communication channel.Therefore,this paper proposes a derivation matrix-based covert communication method in blockchain.It uses dual-key to derive two types of blockchain addresses and then constructs an address matrix by dividing addresses into multiple layers to make full use of the redundancy of addresses.Subsequently,to solve the problem of the lack of concealment caused by the fixed transaction behaviors,divide the rectangular matrix into square blocks with overlapping regions and then encrypt different blocks sequentially to make the transaction behaviors of the channel addresses match better with those of the real addresses.Further,the linear congruence algorithm is used to generate random sequence,which provides a random order for blocks encryption,and thus enhances the security of the encryption algorithm.Experimental results show that this method can effectively reduce the abnormal transaction behaviors of addresses while ensuring the channel transmission efficiency.

Reawakened Sexual Interest: The Result of Surgical Correction of Concealed Penis

Concealed penis (CP) is a developmental anomaly in which the penis is hidden in the skin of the abdomen, thigh or scrotum. As a result of this, the penis appears shortened in length. It was first described by Keyes Jr. E.L. in 1919. It can be associated with voiding problem and in adults, sexual issues, among others. Objective: To show that surgery can reverse celibacy induced by CP and highlight the need for an interdisciplinary approach to correction of this anomaly. Patient and Method: A thirty-one-year male patient who had a surgical release of his buried penis by two surgeons in 2019 in a private hospital. The case note was reviewed, the data obtained analyzed and the results including photographs, were presented. The patient was followed up. Result: A 10 cm length of penis and a hundred percent (100%) take of sheet of split skin graft used to resurface the denuded penis were achieved using combined spinal and epidural anesthesia. The patient, his mother and the surgeons were satisfied with the outcome. Consequently, he resolved to marry a wife after all. Conclusion: Concealed penis can now be regarded as a known cause of celibacy and surgical correction can reverse the celibate state.

隐身材料研究开发现状与矿物材料在其中的应用

本文简要介绍了隐身技术中的电磁波吸收材料及矿物材料的研究开发现状。并针对日益严重的电磁波环境污染等问题 ,讨论了矿物材料在电磁波污染防治、隐身技术和远红外吸收制品等方面的应用前景及应注意的问题。