Most recently, due to the demand of immersive communication, region-of-interest-based(ROI) high efficiency video coding(HEVC) approaches in conferencing scenarios have become increasingly important. However, there exi...Most recently, due to the demand of immersive communication, region-of-interest-based(ROI) high efficiency video coding(HEVC) approaches in conferencing scenarios have become increasingly important. However, there exists no objective metric, specially developed for efficiently evaluating the perceived visual quality of video conferencing coding. Therefore, this paper proposes a novel objective quality assessment method, namely Gaussian mixture model based peak signal-tonoise ratio(GMM-PSNR), for the perceptual video conferencing coding. First, eye tracking experiments, together with a real-time technique of face and facial feature extraction, are introduced. In the experiments, importance of background, face, and facial feature regions is identified, and it is then quantified based on eye fixation points over test videos. Next, assuming that the distribution of the eye fixation points obeys Gaussian mixture model, we utilize expectation-maximization(EM) algorithm to generate an importance weight map for each frame of video conferencing coding, in light of a new term eye fixation points/pixel(efp/p). According to the generated weight map, GMM-PSNR is developed for quality assessment by assigning different weights to the distortion of each pixel in the video frame. Finally, we utilize some experiments to investigate the correlation of the proposed GMM-PSNR and other conventional objective metrics with subjective quality metrics. The experimental results show the effectiveness of GMM-PSNR.展开更多
Coronavirus(COVID-19)is a contagious disease that causes exceptional effect on healthcare organizationsworldwide with dangerous impact on medical services within the hospitals.Because of the fast spread of COVID-19,th...Coronavirus(COVID-19)is a contagious disease that causes exceptional effect on healthcare organizationsworldwide with dangerous impact on medical services within the hospitals.Because of the fast spread of COVID-19,the healthcare facilities could be a big source of disease infection.So,healthcare video consultations should be used to decrease face-to-face communication between clinician and patients.Healthcare video consultations may be beneficial for some COVID-19 conditions and reduce the need for faceto-face contact with a potentially positive patient without symptoms.These conditions are like top clinicians who provide remote consultations to develop treatment methodology and follow-up remotely,patients who consult about COVID-19,and those who have mild symptoms suggestive of the COVID-19 virus.Video consultations are a supplement to,and not a substitute for,telephone consultations.It may also form part of a broader COVID-19 distance care strategy that contains computerized screening,separation of possibly infectious patients within medical services,and computerized video-intensive observing of their intensive care that helps reduce mixing.Nowadays,the spread of the COVID-19 virus helps to expand the use of video healthcare consultations because it helps to exchange experiences and remote medical consultations,save costs and health procedures used to cope with the pandemic of the COVID-19 virus,and monitor the progress of treatment plans,moment by moment from a distance with precision,clarity and ease.From this perspective,this paper introduces a high-efficiency video coding(HEVC)ChaCha20-based selective encryption(SE)scheme for secure healthcare video Consultations.The proposed HEVC ChaCha20-based SE scheme uses the ChaCha20 for encrypting the sign bits of the Discrete Cosine Transform(DCT)and Motion Vector Difference(MVD)in the HEVC entropy phase.The main achievement of HEVC ChaCha20-based SE scheme is encrypting the most sensitive video bits with keeping low delay time,fixed bit rate of the HEVC,and format compliance.Experimental tests guarantee that the proposed HEVC ChaCha20-based SE scheme can ensure the confidentiality of the healthcare video consultations which has become easy to transmit through the internet.展开更多
In order to overcome the defects of the dedicated video conference remote control, this paper designs and implements a Qt-based cross-platform video conferencing remote control. The remote control not only implements ...In order to overcome the defects of the dedicated video conference remote control, this paper designs and implements a Qt-based cross-platform video conferencing remote control. The remote control not only implements a full range of video conferencing control functions with an easy-to-use visual interface;but also implement cross-platform feature to allow users to use remote control software on their own equipment. It is economic, convenient and stylish for users. This paper mainly describes the design and implementation of remote control system framework and cross-platform features. Finally, the result in the paper shows: This remote control is reliable and easy to use.展开更多
Measurement-device-independent quantum cryptographic conferencing(MDI-QCC) protocol puts MDI quantum key distribution(MDI-QKD) forwards to multi-party applications, and suggests a significant framework for practical m...Measurement-device-independent quantum cryptographic conferencing(MDI-QCC) protocol puts MDI quantum key distribution(MDI-QKD) forwards to multi-party applications, and suggests a significant framework for practical multi-party quantum communication. In order to mitigate the experimental complexity of MDI-QCC and remove the key assumption(the sources are trusted) in MDI-QCC, we extend the framework of MDI-QKD with an untrusted source to MDI-QCC and give the rigorous security analysis of MDI-QCC with an untrusted source. What is more, in the security analysis we clearly provide a rigorous analytical method for parameters' estimation, which with simple modifications can be applied to not only MDI-QKD with an untrusted source but also arbitrary multi-party communication protocol with an untrusted source. The simulation results show that at reasonable distances the asymptotic key rates for the two cases(with trusted and untrusted sources) almost overlap, which indicates the feasibility of our protocol.展开更多
Service-Oriented Communication(SOC)is a key research issue to enable media communications using the Service-Oriented Architecture(SOA).Motivated by the necessity to guarantee the service quality of our webbased multim...Service-Oriented Communication(SOC)is a key research issue to enable media communications using the Service-Oriented Architecture(SOA).Motivated by the necessity to guarantee the service quality of our webbased multimedia conferencing system,we present a Comprehensively Context-Aware(CoCA)approach in this paper.One major problem in the existing end-to-end Quality of Service(QoS)management solutions is that they analyse and exploit the relationships between the QoS metrics and corresponding contexts in an isolated manner.In this paper,we propose a novel approach to leveraging such relationships in a comprehensive manner based on Bayesian networks and the fuzzy set theory.This approach includes three phases:1)information feedback and training,2)QoS-to-context mapping,and3)optimal context adaption.We implement the proposed CoCA in the real multimedia conferencing system and compare its performance with the existing bandwidth aware and playback buffer aware schemes.Experimental results show that the proposed CoCA outperforms the competing approaches in improving the average video Peak Signal-to-Noise Ratio(PSNR).It also exhibits good performance in preventing the playback buffer starvation.展开更多
In view of the fact that most college English teachers in China invest a great deal of time and effort responding to students’ writing, but find students improve so little in their writing skills, I venture to put fo...In view of the fact that most college English teachers in China invest a great deal of time and effort responding to students’ writing, but find students improve so little in their writing skills, I venture to put forward an alternative way of teaching writing in the paper, that is, teaching writing through small group conferencing. Compared with the traditional teaching methods small group conferencing has following advantages: (1) Saving evaluation time; (2) Providing better feedback; (3) Helping students critique their writing, etc. Since many empirical studies and teaching practices demonstrate that small group conferencing is an effective and efficient way of teaching writing, we have good reason to believe that it will become widespread in the college English teaching in China. \;展开更多
Video conferencing systems face the dilemma between smooth streaming and decent visual quality because traditional video compression algorithms fail to produce bitstreams low enough for bandwidth-constrained networks....Video conferencing systems face the dilemma between smooth streaming and decent visual quality because traditional video compression algorithms fail to produce bitstreams low enough for bandwidth-constrained networks.An ultra-lightweight face-animation-based method that enables better video conferencing experience is proposed in this paper.The proposed method compresses high-quality upperbody videos with ultra-low bitrates and runs efficiently on mobile devices without high-end graphics processing units(GPU).Moreover,a visual quality evaluation algorithm is used to avoid image degradation caused by extreme face poses and/or expressions,and a full resolution image composition algorithm to reduce unnaturalness,which guarantees the user experience.Experiments show that the proposed method is efficient and can generate high-quality videos at ultra-low bitrates.展开更多
This paper chiefly introduces the model of Video Conferencing System,H.323 standard of ITU-T and RTP/RTCP protocol,and realizes a WAN-Oriented Video Conferencing System—VCSW(Video Conferencing System on WAN).In VCSW,...This paper chiefly introduces the model of Video Conferencing System,H.323 standard of ITU-T and RTP/RTCP protocol,and realizes a WAN-Oriented Video Conferencing System—VCSW(Video Conferencing System on WAN).In VCSW,RTP/RTCP pro-tocol is used for transporting media data and video conference on WAN can be established,so VCSW has abroad application scope.This paper stresses analyzing RTP/RTCP protocol,realizes it and modifies some details of it according to our device condition:re-duces some fields of RTP and RTCP header,removes some information managed by RTP/RTCP.Consequently in testing of lab,good effect is achieved.展开更多
In comparison with almost universal adoption of telephony and mobile technologies in modern day healthcare, video conferencing has yet to become a ubiquitous clinical tool. Currently telehealth services are faced with...In comparison with almost universal adoption of telephony and mobile technologies in modern day healthcare, video conferencing has yet to become a ubiquitous clinical tool. Currently telehealth services are faced with a bewildering range of video conferencing software and hardware choices. This paper provides a case study in the selection of video conferencing services by the Flinders University Telehealth in the Home trial (FTH Trial) to support healthcare in the home. Using pragmatic methods, video conferencing solutions available on the market were assessed for usability, reliability, cost, compatibility, interoperability, performance and privacy considerations. The process of elimination through which the eventual solution was chosen, the selection criteria used for each requirement and the corresponding results are described. The resulting product set, although functional, had restricted ability to directly connect with systems used by healthcare providers elsewhere in the system. This outcome illustrates the impact on one small telehealth provider of the broader struggles between competing video conferencing vendors. At stake is the ability to communicate between healthcare organizations and provide public access to healthcare. Comparison of the current state of the video conferencing market place with the evolution of the telephony system reveals that video conferencing still has a long way to go before it can be considered as easy to use as the telephone. Health organizations that are concerned to improve access and quality of care should seek to influence greater standardization and interoperability though cooperation with one another, the private sector, international organizations and by encouraging governments to play a more active role in this sphere.展开更多
Attenuation due to rain is an important limitation in the designing of the microwave communication links operating at frequencies above 10 GHz. Video conferencing performs over high-speed link via high-speed satellite...Attenuation due to rain is an important limitation in the designing of the microwave communication links operating at frequencies above 10 GHz. Video conferencing performs over high-speed link via high-speed satellite (WINDS satellite) transmission in the Ka-band which is vulnerable to attenuation due to rain. Using the ITU-R proposed models for the prediction of rain attenuation gives a good estimation for the microwave propagation loss caused by rain for the temperate regions, but it underestimates the rain attenuation prediction for the monthly variation of rain rate by averaging annual rain rate for particular region. This study was carried out at the University of Rwanda/Huye Campus. The rain rates were predicted for 0.01 percentage of time from rainfall data measured during two months of July and August using the RD-80 Joss and Waldvogel Disdrometer. From the data collected and analyzed, compared with ITU-R model, we can see that where Rwanda region is situated in region K, what is different from the obtained results because the data are collected during months that coincide with a dry season.展开更多
The purpose of this paper is to present a systematic review of studies that used Video Conferencing (VC) intervention for common chronic conditions. Chronic conditions account for the majority of poor health, disabili...The purpose of this paper is to present a systematic review of studies that used Video Conferencing (VC) intervention for common chronic conditions. Chronic conditions account for the majority of poor health, disability, and death, and for a major portion of health-care expenditures in the United States. Innovative methods and interventions are needed to enhance care and management, improve access to care, improve patient outcomes, narrow health disparities and reduce healthcare costs. Video Conferencing could be particularly relevant in improving health, care management, access and cost in the care of chronic illnesses. A comprehensive literature search process guided by the PRISMA statement led to the inclusion of 27 articles measuring video conferencing, at least one chronic illness, and patient outcomes for adults living in a community setting. While VC has been found to be feasible and effective, a low number of randomized controlled trials limit evidence. In addition, studies in this review were not designed to address the question of whether access to care in rural areas is improved through VC. Hence, more research is needed.展开更多
The multimedia conferencing system is an important tool for Computer supported Cooperative Work (CSCW), and also one of the basic techniques supporting team work in the Concurrent Engineering. In this paper the archit...The multimedia conferencing system is an important tool for Computer supported Cooperative Work (CSCW), and also one of the basic techniques supporting team work in the Concurrent Engineering. In this paper the architecture and function modules of the reported multimedia conferencing system are described. Then in order to reduce the network bandwidth required by the conferencing system, two methods for sending the conferencing data by using multicasting are discussed.展开更多
Video conferencing applications help people communicate via the Internet and provide a significant and consistent basis for virtual meetings.However,integrity,security,identification,and authentication problems are st...Video conferencing applications help people communicate via the Internet and provide a significant and consistent basis for virtual meetings.However,integrity,security,identification,and authentication problems are still universal.Current video conference technologies typically rely on cloud systems to provide a stable and secure basis for executing tasks and processes.At the same time,video conferencing applications are being migrated from centralized to decentralized solutions for better performance without the need for third-party interactions.This article demonstrates a decentralized smart identification scheme for video conferencing applications based on biometric technology,machine learning,and a decentralized hash table combined with blockchain technology.We store users'information on a distributed hash table and transactional events on the distributed ledger after identifying users by implementing machine learning functions.Furthermore,we leverage distributed ledger technology's immutability and traceability properties and distributed hash table unlimited storage feature to improve the system's storage capacity and immutability by evaluating three possible architectures.The experimental results show that an architecture based on blockchain and distributed hash table has better efficiency but needs a longer time to execute than the two other architectures using a centralized database.展开更多
In view of the fact that most college English teachers in China invest a great deal of time andeffort responding to students’ writing,but find students improve so little in their writing skills,I ventureto put forwar...In view of the fact that most college English teachers in China invest a great deal of time andeffort responding to students’ writing,but find students improve so little in their writing skills,I ventureto put forward an alternative way of teaching writing in the paper,that is,teaching writing throughsmall group conferencing.Compared with the traditional teaching methods,small group conferencing hasfollowing advantages:(1)Saving evaluation time;(2)Providing better feedback;(3)Helping studentscritique their writing,etc.Since many empirical studies and teaching practices demonstrate that smallgroup conferencing is an effective and efficient way of teaching writing,we have good reason to believethat it will become widespread in the college English teaching in China.展开更多
Current typical video conferencing connection is bridged by a multipoint control unit(MCU),which may cause large delay and communication bottleneck for the whole system.With the development of network technology,a vid...Current typical video conferencing connection is bridged by a multipoint control unit(MCU),which may cause large delay and communication bottleneck for the whole system.With the development of network technology,a video conferencing system can be implemented based on software-defined networking(SDN),which makes the service controllable and improves the scalability and flexibility.Additionally,a video encoding method called scalable video coding(SVC) can also help.In this paper,we propose a video conferencing architecture based on SDN-enabled SVC multicasting,which discards the traditional Internet group management protocol(IGMP) and MCU.The system implements SVC multicast streaming to satisfy different device capabilities of various conference terminals.The SDN controller is responsible for dynamically managing and controlling the layers of a video stream when a conference member faces network congestion.Also,a conference manager is designed to facilitate the management of the conference members.Experimental results show that our system can not only provide a flexible and controllable video delivery,but also reduce the network usage while guaranteeing the quality of service(QoS) of video conferencing.展开更多
In desktop video conferencing systems, the quality of video as well as the response speed of user′s data is important element of systematic performance. In this paper, four video and data multiplexing strategies in t...In desktop video conferencing systems, the quality of video as well as the response speed of user′s data is important element of systematic performance. In this paper, four video and data multiplexing strategies in terminals: the Alternate Method, the Video Priority Method, the Data Priority Method, and the Dynamic Priority Method, are investigated. Their influences on transmission performances of data and video are discussed.展开更多
This paper evaluates the performance of Internet Protocol Security (IPSec) based Multiprotocol Label Switching (MPLS) virtual private network (VPN) in a small to medium sized organization. The demand for security in d...This paper evaluates the performance of Internet Protocol Security (IPSec) based Multiprotocol Label Switching (MPLS) virtual private network (VPN) in a small to medium sized organization. The demand for security in data networks has been increasing owing to the high cyber attacks and potential risks associated with networks spread over distant geographical locations. The MPLS networks ride on the public network backbone that is porous and highly susceptible to attacks and so the need for reliable security mechanisms to be part of the deployment plan. The evaluation criteria concentrated on Voice over Internet Protocol (VoIP) and Video conferencing with keen interest in jitter, end to end delivery and general data flow. This study used both structured questionnaire and observation methods. The structured questionnaire was administered to a group of 70 VPN users in a company. This provided the study with precise responses. The observation method was used in data simulations using OPNET Version 14.5 Simulation software. The results show that the IPSec features increase the size of data packets by approximately 9.98% translating into approximately 90.02% effectiveness. The tests showed that the performance metrics are all well within the recommended standards. The IPSec Based MPLS Virtual private network is more stable and secure than one without IPSec.展开更多
This paper discusses SHVC, the scalable extension of the High Efficiency Video Coding (HEVC) standard, and its applications in broadcasting and wireless broadband multimedia services. SHVC was published as part of the...This paper discusses SHVC, the scalable extension of the High Efficiency Video Coding (HEVC) standard, and its applications in broadcasting and wireless broadband multimedia services. SHVC was published as part of the second version of the HEVC specifi?cation in 2014. Since its publication, SHVC has been evaluated by application standards development organizations (SDOs) for its potential benefits in video applications, such as terrestrial and mobile broadcasting in ATSC 3.0, as well as a variety of 3GPP mul?timedia services, including multi?party multi?stream video conferencing (MMVC), multimedia broadcast/multicast service (MBMS), and dynamic adaptive streaming over HTTP (DASH). This paper provides a brief overview of SHVC and the performance and com?plexity analyses of using SHVC in these video applications.展开更多
Giving effective feedback is one of useful methods to improve students' writing.With the aim of offering students more effective feedback,this essay will discuss the new kind of feedback on student writing by intr...Giving effective feedback is one of useful methods to improve students' writing.With the aim of offering students more effective feedback,this essay will discuss the new kind of feedback on student writing by introducing the features of the new approach and evaluating it in Chinese teaching context.According to the study,it is recommended peer feedback and teacher-student conferencing feedback should be implemented in the Chinese classrooms,and the teachers of writing should vary their types of feedback according to students' specific needs.展开更多
With the increase of bi-and multilingual proceedings,videoconference interpreting(VCI)has become common practice in many areas of national and cross-border criminal proceedings.However,the use of VCI has been impeded ...With the increase of bi-and multilingual proceedings,videoconference interpreting(VCI)has become common practice in many areas of national and cross-border criminal proceedings.However,the use of VCI has been impeded by some limits,such as no clear guidelines,lack of training,emotional issues,equipment limits,interaction impacts and inability to represent.Various measures thereby do need to be taken to improve VCI in guidelines,training,three-way interaction,technical support,and location of the defendant solicitor.Though basic practical problems can be addressed quickly,the combined complexities of it with both technological and linguistic-cultural mediation require further research.展开更多
文摘Most recently, due to the demand of immersive communication, region-of-interest-based(ROI) high efficiency video coding(HEVC) approaches in conferencing scenarios have become increasingly important. However, there exists no objective metric, specially developed for efficiently evaluating the perceived visual quality of video conferencing coding. Therefore, this paper proposes a novel objective quality assessment method, namely Gaussian mixture model based peak signal-tonoise ratio(GMM-PSNR), for the perceptual video conferencing coding. First, eye tracking experiments, together with a real-time technique of face and facial feature extraction, are introduced. In the experiments, importance of background, face, and facial feature regions is identified, and it is then quantified based on eye fixation points over test videos. Next, assuming that the distribution of the eye fixation points obeys Gaussian mixture model, we utilize expectation-maximization(EM) algorithm to generate an importance weight map for each frame of video conferencing coding, in light of a new term eye fixation points/pixel(efp/p). According to the generated weight map, GMM-PSNR is developed for quality assessment by assigning different weights to the distortion of each pixel in the video frame. Finally, we utilize some experiments to investigate the correlation of the proposed GMM-PSNR and other conventional objective metrics with subjective quality metrics. The experimental results show the effectiveness of GMM-PSNR.
基金This study was funded by the Deanship of Scientific Research,Taif University Researchers Supporting Project number(TURSP-2020/08),Taif University,Taif,Saudi Arabia.
文摘Coronavirus(COVID-19)is a contagious disease that causes exceptional effect on healthcare organizationsworldwide with dangerous impact on medical services within the hospitals.Because of the fast spread of COVID-19,the healthcare facilities could be a big source of disease infection.So,healthcare video consultations should be used to decrease face-to-face communication between clinician and patients.Healthcare video consultations may be beneficial for some COVID-19 conditions and reduce the need for faceto-face contact with a potentially positive patient without symptoms.These conditions are like top clinicians who provide remote consultations to develop treatment methodology and follow-up remotely,patients who consult about COVID-19,and those who have mild symptoms suggestive of the COVID-19 virus.Video consultations are a supplement to,and not a substitute for,telephone consultations.It may also form part of a broader COVID-19 distance care strategy that contains computerized screening,separation of possibly infectious patients within medical services,and computerized video-intensive observing of their intensive care that helps reduce mixing.Nowadays,the spread of the COVID-19 virus helps to expand the use of video healthcare consultations because it helps to exchange experiences and remote medical consultations,save costs and health procedures used to cope with the pandemic of the COVID-19 virus,and monitor the progress of treatment plans,moment by moment from a distance with precision,clarity and ease.From this perspective,this paper introduces a high-efficiency video coding(HEVC)ChaCha20-based selective encryption(SE)scheme for secure healthcare video Consultations.The proposed HEVC ChaCha20-based SE scheme uses the ChaCha20 for encrypting the sign bits of the Discrete Cosine Transform(DCT)and Motion Vector Difference(MVD)in the HEVC entropy phase.The main achievement of HEVC ChaCha20-based SE scheme is encrypting the most sensitive video bits with keeping low delay time,fixed bit rate of the HEVC,and format compliance.Experimental tests guarantee that the proposed HEVC ChaCha20-based SE scheme can ensure the confidentiality of the healthcare video consultations which has become easy to transmit through the internet.
文摘In order to overcome the defects of the dedicated video conference remote control, this paper designs and implements a Qt-based cross-platform video conferencing remote control. The remote control not only implements a full range of video conferencing control functions with an easy-to-use visual interface;but also implement cross-platform feature to allow users to use remote control software on their own equipment. It is economic, convenient and stylish for users. This paper mainly describes the design and implementation of remote control system framework and cross-platform features. Finally, the result in the paper shows: This remote control is reliable and easy to use.
基金supported by the National Basic Research Program of China(Grant No.2013CB338002)the National Natural Science Foundation of China(Grant Nos.11304397 and 61505261)
文摘Measurement-device-independent quantum cryptographic conferencing(MDI-QCC) protocol puts MDI quantum key distribution(MDI-QKD) forwards to multi-party applications, and suggests a significant framework for practical multi-party quantum communication. In order to mitigate the experimental complexity of MDI-QCC and remove the key assumption(the sources are trusted) in MDI-QCC, we extend the framework of MDI-QKD with an untrusted source to MDI-QCC and give the rigorous security analysis of MDI-QCC with an untrusted source. What is more, in the security analysis we clearly provide a rigorous analytical method for parameters' estimation, which with simple modifications can be applied to not only MDI-QKD with an untrusted source but also arbitrary multi-party communication protocol with an untrusted source. The simulation results show that at reasonable distances the asymptotic key rates for the two cases(with trusted and untrusted sources) almost overlap, which indicates the feasibility of our protocol.
基金supported by the NationalBasic Research Program of China(973 Program)under Grants No.2011CB302506,No.2011CB302704,No.2012CB315802the National Key Technologies Research and Development Program of China"Research on theMobile Community Cultural Service Aggregation Supporting Technology"under Grant No.2012BAH94F02+5 种基金the Novel Mobile ServiceControl Network Architecture and Key Technologies under Grant No.2010ZX03004001-01the National High Technical Researchand Development Program of China(863 Program)under Grant No.2013AA102301the National Natural Science Foundation of Chinaunder Grants No.61003067,No.61171102,No.61001118,No.61132001Program for NewCentury Excellent Talents in University underGrant No.NCET-11-0592the Project of NewGeneration Broadband Wireless Network under Grant No.2011ZX03002-002-01the Beijing Nova Program under Grant No.2008B50
文摘Service-Oriented Communication(SOC)is a key research issue to enable media communications using the Service-Oriented Architecture(SOA).Motivated by the necessity to guarantee the service quality of our webbased multimedia conferencing system,we present a Comprehensively Context-Aware(CoCA)approach in this paper.One major problem in the existing end-to-end Quality of Service(QoS)management solutions is that they analyse and exploit the relationships between the QoS metrics and corresponding contexts in an isolated manner.In this paper,we propose a novel approach to leveraging such relationships in a comprehensive manner based on Bayesian networks and the fuzzy set theory.This approach includes three phases:1)information feedback and training,2)QoS-to-context mapping,and3)optimal context adaption.We implement the proposed CoCA in the real multimedia conferencing system and compare its performance with the existing bandwidth aware and playback buffer aware schemes.Experimental results show that the proposed CoCA outperforms the competing approaches in improving the average video Peak Signal-to-Noise Ratio(PSNR).It also exhibits good performance in preventing the playback buffer starvation.
文摘In view of the fact that most college English teachers in China invest a great deal of time and effort responding to students’ writing, but find students improve so little in their writing skills, I venture to put forward an alternative way of teaching writing in the paper, that is, teaching writing through small group conferencing. Compared with the traditional teaching methods small group conferencing has following advantages: (1) Saving evaluation time; (2) Providing better feedback; (3) Helping students critique their writing, etc. Since many empirical studies and teaching practices demonstrate that small group conferencing is an effective and efficient way of teaching writing, we have good reason to believe that it will become widespread in the college English teaching in China. \;
文摘Video conferencing systems face the dilemma between smooth streaming and decent visual quality because traditional video compression algorithms fail to produce bitstreams low enough for bandwidth-constrained networks.An ultra-lightweight face-animation-based method that enables better video conferencing experience is proposed in this paper.The proposed method compresses high-quality upperbody videos with ultra-low bitrates and runs efficiently on mobile devices without high-end graphics processing units(GPU).Moreover,a visual quality evaluation algorithm is used to avoid image degradation caused by extreme face poses and/or expressions,and a full resolution image composition algorithm to reduce unnaturalness,which guarantees the user experience.Experiments show that the proposed method is efficient and can generate high-quality videos at ultra-low bitrates.
基金Approval No. of the National Natural ScienceFund: 60573182
文摘This paper chiefly introduces the model of Video Conferencing System,H.323 standard of ITU-T and RTP/RTCP protocol,and realizes a WAN-Oriented Video Conferencing System—VCSW(Video Conferencing System on WAN).In VCSW,RTP/RTCP pro-tocol is used for transporting media data and video conference on WAN can be established,so VCSW has abroad application scope.This paper stresses analyzing RTP/RTCP protocol,realizes it and modifies some details of it according to our device condition:re-duces some fields of RTP and RTCP header,removes some information managed by RTP/RTCP.Consequently in testing of lab,good effect is achieved.
文摘In comparison with almost universal adoption of telephony and mobile technologies in modern day healthcare, video conferencing has yet to become a ubiquitous clinical tool. Currently telehealth services are faced with a bewildering range of video conferencing software and hardware choices. This paper provides a case study in the selection of video conferencing services by the Flinders University Telehealth in the Home trial (FTH Trial) to support healthcare in the home. Using pragmatic methods, video conferencing solutions available on the market were assessed for usability, reliability, cost, compatibility, interoperability, performance and privacy considerations. The process of elimination through which the eventual solution was chosen, the selection criteria used for each requirement and the corresponding results are described. The resulting product set, although functional, had restricted ability to directly connect with systems used by healthcare providers elsewhere in the system. This outcome illustrates the impact on one small telehealth provider of the broader struggles between competing video conferencing vendors. At stake is the ability to communicate between healthcare organizations and provide public access to healthcare. Comparison of the current state of the video conferencing market place with the evolution of the telephony system reveals that video conferencing still has a long way to go before it can be considered as easy to use as the telephone. Health organizations that are concerned to improve access and quality of care should seek to influence greater standardization and interoperability though cooperation with one another, the private sector, international organizations and by encouraging governments to play a more active role in this sphere.
文摘Attenuation due to rain is an important limitation in the designing of the microwave communication links operating at frequencies above 10 GHz. Video conferencing performs over high-speed link via high-speed satellite (WINDS satellite) transmission in the Ka-band which is vulnerable to attenuation due to rain. Using the ITU-R proposed models for the prediction of rain attenuation gives a good estimation for the microwave propagation loss caused by rain for the temperate regions, but it underestimates the rain attenuation prediction for the monthly variation of rain rate by averaging annual rain rate for particular region. This study was carried out at the University of Rwanda/Huye Campus. The rain rates were predicted for 0.01 percentage of time from rainfall data measured during two months of July and August using the RD-80 Joss and Waldvogel Disdrometer. From the data collected and analyzed, compared with ITU-R model, we can see that where Rwanda region is situated in region K, what is different from the obtained results because the data are collected during months that coincide with a dry season.
文摘The purpose of this paper is to present a systematic review of studies that used Video Conferencing (VC) intervention for common chronic conditions. Chronic conditions account for the majority of poor health, disability, and death, and for a major portion of health-care expenditures in the United States. Innovative methods and interventions are needed to enhance care and management, improve access to care, improve patient outcomes, narrow health disparities and reduce healthcare costs. Video Conferencing could be particularly relevant in improving health, care management, access and cost in the care of chronic illnesses. A comprehensive literature search process guided by the PRISMA statement led to the inclusion of 27 articles measuring video conferencing, at least one chronic illness, and patient outcomes for adults living in a community setting. While VC has been found to be feasible and effective, a low number of randomized controlled trials limit evidence. In addition, studies in this review were not designed to address the question of whether access to care in rural areas is improved through VC. Hence, more research is needed.
文摘The multimedia conferencing system is an important tool for Computer supported Cooperative Work (CSCW), and also one of the basic techniques supporting team work in the Concurrent Engineering. In this paper the architecture and function modules of the reported multimedia conferencing system are described. Then in order to reduce the network bandwidth required by the conferencing system, two methods for sending the conferencing data by using multicasting are discussed.
基金This work has been supported by the Kolarctic CBC project DIT4-BEARS under grant KO4096.
文摘Video conferencing applications help people communicate via the Internet and provide a significant and consistent basis for virtual meetings.However,integrity,security,identification,and authentication problems are still universal.Current video conference technologies typically rely on cloud systems to provide a stable and secure basis for executing tasks and processes.At the same time,video conferencing applications are being migrated from centralized to decentralized solutions for better performance without the need for third-party interactions.This article demonstrates a decentralized smart identification scheme for video conferencing applications based on biometric technology,machine learning,and a decentralized hash table combined with blockchain technology.We store users'information on a distributed hash table and transactional events on the distributed ledger after identifying users by implementing machine learning functions.Furthermore,we leverage distributed ledger technology's immutability and traceability properties and distributed hash table unlimited storage feature to improve the system's storage capacity and immutability by evaluating three possible architectures.The experimental results show that an architecture based on blockchain and distributed hash table has better efficiency but needs a longer time to execute than the two other architectures using a centralized database.
文摘In view of the fact that most college English teachers in China invest a great deal of time andeffort responding to students’ writing,but find students improve so little in their writing skills,I ventureto put forward an alternative way of teaching writing in the paper,that is,teaching writing throughsmall group conferencing.Compared with the traditional teaching methods,small group conferencing hasfollowing advantages:(1)Saving evaluation time;(2)Providing better feedback;(3)Helping studentscritique their writing,etc.Since many empirical studies and teaching practices demonstrate that smallgroup conferencing is an effective and efficient way of teaching writing,we have good reason to believethat it will become widespread in the college English teaching in China.
基金supported by the National Natural Science Foundation of China(Nos.61573329 and 61233003)the Youth Innovation Promotion Association CASthe Fundamental Research Funds for the Central Universities,China
文摘Current typical video conferencing connection is bridged by a multipoint control unit(MCU),which may cause large delay and communication bottleneck for the whole system.With the development of network technology,a video conferencing system can be implemented based on software-defined networking(SDN),which makes the service controllable and improves the scalability and flexibility.Additionally,a video encoding method called scalable video coding(SVC) can also help.In this paper,we propose a video conferencing architecture based on SDN-enabled SVC multicasting,which discards the traditional Internet group management protocol(IGMP) and MCU.The system implements SVC multicast streaming to satisfy different device capabilities of various conference terminals.The SDN controller is responsible for dynamically managing and controlling the layers of a video stream when a conference member faces network congestion.Also,a conference manager is designed to facilitate the management of the conference members.Experimental results show that our system can not only provide a flexible and controllable video delivery,but also reduce the network usage while guaranteeing the quality of service(QoS) of video conferencing.
文摘In desktop video conferencing systems, the quality of video as well as the response speed of user′s data is important element of systematic performance. In this paper, four video and data multiplexing strategies in terminals: the Alternate Method, the Video Priority Method, the Data Priority Method, and the Dynamic Priority Method, are investigated. Their influences on transmission performances of data and video are discussed.
文摘This paper evaluates the performance of Internet Protocol Security (IPSec) based Multiprotocol Label Switching (MPLS) virtual private network (VPN) in a small to medium sized organization. The demand for security in data networks has been increasing owing to the high cyber attacks and potential risks associated with networks spread over distant geographical locations. The MPLS networks ride on the public network backbone that is porous and highly susceptible to attacks and so the need for reliable security mechanisms to be part of the deployment plan. The evaluation criteria concentrated on Voice over Internet Protocol (VoIP) and Video conferencing with keen interest in jitter, end to end delivery and general data flow. This study used both structured questionnaire and observation methods. The structured questionnaire was administered to a group of 70 VPN users in a company. This provided the study with precise responses. The observation method was used in data simulations using OPNET Version 14.5 Simulation software. The results show that the IPSec features increase the size of data packets by approximately 9.98% translating into approximately 90.02% effectiveness. The tests showed that the performance metrics are all well within the recommended standards. The IPSec Based MPLS Virtual private network is more stable and secure than one without IPSec.
文摘This paper discusses SHVC, the scalable extension of the High Efficiency Video Coding (HEVC) standard, and its applications in broadcasting and wireless broadband multimedia services. SHVC was published as part of the second version of the HEVC specifi?cation in 2014. Since its publication, SHVC has been evaluated by application standards development organizations (SDOs) for its potential benefits in video applications, such as terrestrial and mobile broadcasting in ATSC 3.0, as well as a variety of 3GPP mul?timedia services, including multi?party multi?stream video conferencing (MMVC), multimedia broadcast/multicast service (MBMS), and dynamic adaptive streaming over HTTP (DASH). This paper provides a brief overview of SHVC and the performance and com?plexity analyses of using SHVC in these video applications.
文摘Giving effective feedback is one of useful methods to improve students' writing.With the aim of offering students more effective feedback,this essay will discuss the new kind of feedback on student writing by introducing the features of the new approach and evaluating it in Chinese teaching context.According to the study,it is recommended peer feedback and teacher-student conferencing feedback should be implemented in the Chinese classrooms,and the teachers of writing should vary their types of feedback according to students' specific needs.
文摘With the increase of bi-and multilingual proceedings,videoconference interpreting(VCI)has become common practice in many areas of national and cross-border criminal proceedings.However,the use of VCI has been impeded by some limits,such as no clear guidelines,lack of training,emotional issues,equipment limits,interaction impacts and inability to represent.Various measures thereby do need to be taken to improve VCI in guidelines,training,three-way interaction,technical support,and location of the defendant solicitor.Though basic practical problems can be addressed quickly,the combined complexities of it with both technological and linguistic-cultural mediation require further research.
