Multiparty Videoconferencing Research Articles

Qualitative Assessment of Rapid System Transformation to Primary Care Video Visits at an Academic Medical Center.

The coronavirus disease 2019 pandemic spurred health systems across the world to quickly shift from in-person visits to safer video visits. To seek stakeholder perspectives on video visits' acceptability and effect 3 weeks after near-total transition to video visits. Semistructured qualitative interviews. 6 Stanford general primary care and express care clinics at 6 northern California sites, with 81 providers, 123 staff, and 97614 patient visits in 2019. 53 program participants (overlapping roles as medical providers [n = 20], medical assistants [n = 16], nurses [n = 4], technologists [n = 4], and administrators [n = 13]) were interviewed about video visit transition and challenges. In 3 weeks, express care and primary care video visits increased from less than 10% to greater than 80% and from less than 10% to greater than 75%, respectively. New video visit providers received video visit training and care quality feedback. New system workflows were created to accommodate the new visit method. 9 faculty, trained in qualitative research methods, conducted 53 stakeholder interviews in 4 days using purposeful (administrators and technologists) and convenience (medical assistant, nurses, and providers) sampling. A rapid qualitative analytic approach for thematic analysis was used. The analysis revealed 12 themes, including Pandemic as Catalyst; Joy in Medicine; Safety in Medicine; Slipping Through the Cracks; My Role, Redefined; and The New Normal. Themes were analyzed using the RE-AIM (reach, effectiveness, adoption, implementation, and maintenance) framework to identify critical issues for continued program utilization. Evaluation was done immediately after deployment. Although viewpoints may have evolved later, immediate evaluation allowed for prompt program changes and identified broader issues to address for program sustainability. After pandemic-related systems transformation at Stanford, critical issues to sustain video visit long-term viability were identified. Specifically, technology ease of use must improve and support multiparty videoconferencing. Providers should be able to care for their patients, regardless of geography. Providers need decision-making support with virtual examination training and home-based patient diagnostics. Finally, ongoing video visit reimbursement should be commensurate with value to the patients' health and well-being. Stanford Department of Medicine and Stanford Health Care.

How to Prevent Technical Issues in Large Multiparty Medical Videoconferencing

Introduction: Videoconferencing (VC) is useful for physicians who need to learn about many cases without moving from one institution to another. However, this advantage can be hampered by technical issues. This study aims to analyse the factors relating technical support that cause technical issues in regular multiparty medical VC to provide high-quality VC to meet participants’ demands. Methods: The study includes large multiparty VC between the Kyushu University Hospital Department of Paediatric Surgery and different institutions within Japan that were held from September 2014 to January 2017. Technical tests, a “previous-week test” and a “last-hour test,” were conducted for checking conditions prior to the VC. The chi-square test was used for factors: participation for previous-week and last-hour test, and attendance by an engineer VCs in each participating institution. A questionnaire survey was distributed among the participants to collect feedback on the quality of VC, ease of preparation and necessity of previous-week testing. Results: Participation in the last-hour test (P=0.002) and the presence of an engineer (P=0.049) significantly decreased overall technical issues. The last-hour tests significantly decreased disconnection (P=0.015) and audio (P=0.019) issues. The engineer’s attendance decreased content-sharing issues (P=0.027). Participants reporting “very good” and “good” audio and visual quality were 92% (109/118) and 96% (105/110). Eighty-three percent of participants (82/99) found the preparation “very easy” or “easy”; while 61% (63/103) found the previous-week test, “unnecessary.” Conclusions: Based on our study, “engineers’ attendance” and “last-hour” technical testing significantly reduced technical problems; these factors help provide high-quality output VC and meet the needs of the participants.

Distributed Rate Allocation in Switch-Based Multiparty Videoconferencing System

Multiparty videoconferences, or more generally multiparty video calls, are gaining a lot of popularity as they offer a rich communication experience. These applications have, however, large requirements in terms of both network and computational resources and have to deal with sets of heterogenous clients. The multiparty videoconferencing systems are usually either based on expensive central nodes, called Multipoint Control Units (MCU), with transcoding capabilities, or on a peer-to-peer architecture where users cooperate to distribute more efficiently the different video streams. Whereas the first class of systems requires an expensive central hardware, the second one depends completely on the redistribution capacity of the users, which sometimes might neither provide sufficient bandwidth nor be reliable enough. In this work, we propose an alternative solution where we use a central node to distribute the video streams, but at the same time we maintain the hardware complexity and the computational requirements of this node as low as possible, for example, it has no video decoding capabilities. We formulate the rate allocation problem as an optimization problem that aims at maximizing the Quality of Service (QoS) of the videoconference. We propose two different distributed algorithms for solving the optimization problem: the first algorithm is able to find an approximate solution of the problem in a one-shot execution, whereas the second algorithm, based on Lagrangian relaxation, performs iterative updates of the optimization variables in order to gradually increase the value of the objective function. The two algorithms, though being disjointed, nicely complement each other. If executed in sequence, they allow us to achieve both a quick approximate rate reallocation, in case of a sudden change of the system conditions, and a precise refinement of the variables, which avoids problems caused by possible faulty approximate solutions. We have further implemented our solution in a network simulator where we show that our rate allocation algorithm is able to properly optimize users’ QoS. We also illustrate the benefits of our solution in terms of network usage and overall utility when compared to a baseline heuristic method operating on the same system architecture.

CoolConferencing: Enabling Robust Peer-to-Peer Multi-Party Video Conferencing

Multi-party video conferencing (MPVC) is the next big opportunity for Internet streaming. Commercial MPVC solutions are either server-based or peer-to-peer (P2P)-based, which both have performance limitations. P2P technology is expected to dominate the MPVC platform. There are four requirements for a robust MPVC system: 1) realistic network assumptions; 2) realistic system settings; 3) multi-rate support; and 4) any-view support. Existing academic works study the problem from a theoretical perspective, and none of them meets all four requirements simultaneously. We design CoolConferencing, an overlay network for robust P2P MPVC. The core operations follow the easy-to-implement, robust, and resilient data-driven principle, which does not maintain complex global structures such as dissemination trees and can adapt to network dynamic distributedly and quickly. CoolConferencing is a robust system that meets all four requirements simultaneously. In addition, to the best of our knowledge, there is no existing work which examines its MPVC approach under various realistic network environments. We have evaluated CoolConferencing via an event-driven simulation. Compared with state-of-the-art video conferencing solutions, CoolConferencing achieves around 25% gain than Mutualcast and around 9% gain than Celerity in performance. Moreover, when the helper mechanism is enabled, CoolConferencing can easily exploit all available bandwidth to get optimal video transmission performance.

Dealing With User Heterogeneity in P2P Multi-Party Video Conferencing: Layered Distribution Versus Partitioned Simulcast

We consider peer-to-peer multi-party video conferencing (P2P-MPVC), where users with different uplink -downlink capacities send their videos using multicast trees. One way to deal with user bandwidth heterogeneity is employing layered video coding, generating multiple layers with different rates, whereas an alternative is partitioning the receivers of each source and disseminating a different non-layered video version within each group. In this paper, we aim to maximize the received video quality for both systems under uplink-downlink capacity constraints, while constraining the number of hops the packets traverse to two. We first show any multicast tree is equivalent to a collection of 1-hop and 2-hop trees, under user uplink-downlink capacity constraints. This reveals that the packet overlay hop count can be limited to two without sacrificing the achievable rate performance. Assuming a fine granularity scalable stream that can be truncated at any rate, we propose an algorithm that solves for the number of video layers, layer rates, and distribution trees for the layered system. For the partitioned simulcast system, we develop an algorithm to determine the receiver partitions along with the video rate and the distribution trees for each group. Through numerical comparison, we show that the partitioned simulcast system achieves the same average receiving quality as the ideal layered system without any coding overhead for the four-user systems simulated, and better quality than the layered system when the layered coding overhead is only 20%. The two systems perform similarly for the six-user case if the layered coding overhead is 10%.

A P2P-MCU Approach to Multi-Party Video Conference with WebRTC

A P2P-MCU Approach to Multi-Party Video Conference with WebRTC

Enabling P2P One-View Multiparty Video Conferencing

Multiparty video conferencing (MPVC) facilitates real-time group interaction between users. While P2P is a natural delivery solution for MPVC, a peer often does not have enough bandwidth to deliver her video to all other peers in the conference. Recently, we have witnessed the popularity of one-view MPVC, where each user only watches full video of another user. One-view MPVC opens up the design space for P2P delivery. In this paper, we explore the feasibility of a pure P2P solution for one-view MPVC. We characterize the video source rate region achievable through video relays between peers. For both homogeneous and heterogeneous MPVC systems, we establish tight universal video rate lower bounds that are independent of the number of peers, the number of video sources, and the specific viewing relations between peers. We further propose, P2P video relay designs to approach the maximal video rate region. Through numerical simulations, we verified that the derived lower bounds are indeed tight bounds, and the proposed bandwidth allocation algorithm can achieve a close-to-optimal peer upload bandwidth utilization. Our results demonstrate that P2P is a promising solution for one-view MPVC. Insights obtained from our study can be used to guide the design of P2P MPVC systems.

Performance Analysis and Implementation of SIP Multi-party Video Conference System

Through an analysis of Session Initiation Protocol (SIP), with a combination of the characteristics of video conference system, this paper puts forward a SIP video conference system based on the hierarchical network architecture. After an exhaustive analysis of the architecture and working principle of the system, this paper comes up with a system implementation method, as well as makes a performance analysis and functional verification of the system by writing corresponding test cases. The experiment results show that this system not only breaks the bottleneck of the existing system, but also efficiently upgrades the system capacity.

Software-based serverless endpoint video combiner architecture for high-definition multiparty video conferencing

This paper proposes an endpoint video combiner architecture in a multipoint control unit (MCU) system for high definition multiparty video conferencing. The proposed architecture addresses the current reliability, computational and quality drawbacks of a conventional centralized based video combiner architecture. This is achieved by redesigning the MCU video to move away the video combiner from the bridge and into the client endpoints. Moreover, the proposed architecture represents a serverless system and is able to scale a large number of clients at high resolutions in a multipoint video conferencing session. In order to realize this design, this paper also proposes a custom robust sustainable session management protocol which allows a dynamic multi-port management between the MCU video and client endpoints. In addition, the proposed custom session management protocol includes recommendation for a session protection structure. Experimental results suggest that the proposed architecture exhibits significant computational frame rate performance gains of up to 762.95% in comparison with the conventional centralized video combiner architecture based on a series of four and eight high definition combined video assessments. Moreover, reliability analysis suggests that the proposed architecture is also able to consistently sustain a high frame rate performance within a long duration high definition multipoint video conferencing session.

Advanced Transition/Cluster Key Management Scheme for End-System Multicast Protocol

The recent growth of the World Wide Web has sparked new research into using the Internet for novel types of group communication, like multiparty videoconferencing and real-time streaming. Multicast has the potential to be very useful, but it suffers from many problems like security. To achieve secure multicast communications with the dynamic aspect of group applications due to free membership joins and leaves in addition to member's mobility, key management is of the most critical problems. So far, a lot of multicast key management schemes have been proposed and most of them are centralized, which have the problem of one point failure and that the group controller is the bottleneck of the group. In order to solve these two problems, we propose a Key Management Scheme, using cluster-based End-System Multicast (ESM). The group management is between both 1) the main controller (MRP, Main Rendezvous Point) and the second controllers (CRP, Cluster RP), and 2) the second controllers (CRPs) and its members. So, ESM simplifies the implementation of group communication and is efficient ways to deliver a secure message to a group of recipients in a network as a practical alternative to overcome the difficulty of large scale deployment of traditional IP multicast. In this paper, we analyze different key management schemes and propose a new scheme, namely Advanced Transition/Cluster Key management Scheme (ATCKS) and find it has appropriate performance in security.

Conference Management and Speech Enhancement for Multiparty Video Conference over the MPLS Networks

Conference Management and Speech Enhancement for Multiparty Video Conference over the MPLS Networks

Optimal Bandwidth Sharing in Multiswarm Multiparty P2P Video-Conferencing Systems

In a multiparty video conference, multiple users simultaneously distribute video streams to their receivers. As the traditional server-based solutions incur high infrastructure and bandwidth cost, conventional peer-to-peer (P2P) solutions only leveraging end-users' upload bandwidth are normally not self-sustainable: The video streaming workload increases quadratically with the number of users as each user could generate and distribute video streams, while the user upload bandwidth only increases linearly. Recently, hybrid solutions have been proposed that employ helpers to address the bandwidth deficiency in P2P video-conferencing swarms. It is also noticed that a system hosting multiple parallel conferencing swarms can benefit from cross-swarm bandwidth sharing. However, how to optimally share bandwidth in such systems has not been explored so far. In this paper, we study the optimal bandwidth sharing in multiswarm multiparty P2P video-conferencing systems with helpers and investigate two cross-swarm bandwidth-sharing scenarios: (1) swarms are independent and peers from different swarms share a common pool of helpers; (2) swarms are cooperative and peers in a bandwidth-rich swarm can further share their bandwidth with peers in a bandwidth-poor swarm. For each scenario, we develop distributed algorithms for intraswarm and interswarm bandwidth allocation under a utility-maximization framework. Through analysis and simulation, we show that the proposed algorithms are robust to peer dynamics and can adaptively allocate peer and helper bandwidth across swarms so as to achieve the system-wide optimum.

A Multiparty Videoconferencing System Over an Application-Level Multicast Protocol

Increased speeds of PCs and networks have made media communications possible on the Internet. Today, the need for desktop videoconferencing is experiencing robust growth in both business and consumer markets. However, the synchronous delivery of high-volume media content is still a big challenge under a current heterogeneous Internet environment. In this paper, we present a multiparty videoconferencing system based on a peer-to-peer (P2P) solution. The contribution of our paper is twofold. On the one hand, we design an application-level multicast scheme which intends to tolerate the heterogeneity in videoconferencing applications. Design tradeoffs are analyzed and our decisions are made based on extensive experimentation. On the other, we design a five-layer architecture for implementing a multiparty videoconferencing system. This architecture makes a clear-cut distinction between different functional modules and therefore provides rich flexibility in feature adaptation. We believe that our work can be a helpful reference in other efforts on building desktop videoconferencing systems.

A Study on Gaze Awareness of Multiparty Videoconference for IshinDenshin System based on Two Cameras

A Study on Gaze Awareness of Multiparty Videoconference for IshinDenshin System based on Two Cameras

Efficient Group Coordination in Multicast Trees

The majority of today's Internet applications relies on point-to-point communication. In recent years, however, multipoint communication support has become the foundation for such applications as multiparty video conferencing, distributed interactive simulations, and collaborative systems. We describe a novel protocol to coordinate multipoint groupwork within the IP-multicast framework. The protocol supports Internet-wide coordination for large and highly-interactive groupwork, relying on the dissemination of coordination directives among group members across a shared end-to-end multicast tree. We also describe how addressing extensions to IP multicast can be used for our multisite coordination mechanism.

Architectural design and bandwidth demand analysis for multiparty videoconferencing on SONET/ATM rings

In this paper, we propose a scheme for implementing multiparty videoconferencing service on SONET/ATM rings. We focus on the architectural design and bandwidth demand analysis. Different multicasting methods on SONET/ATM rings are discussed and compared. A new multicast virtual path (VP) called Multidrop which is particularly suitable for SONET/ATM rings is proposed. An add-drop multiplexer (ADM) structure for rings capable of multidropping is also presented. Several VP assignment schemes are proposed and their bandwidth utilizations are compared.

Traffic analysis for multiparty videoconferencing in virtual path‐based ATM networks

Traffic analysis for multiparty videoconferencing in virtual path‐based ATM networks

Traffic analysis for multiparty videoconferencing in virtual path-based ATM networks

Traffic analysis for multiparty videoconferencing in virtual path-based ATM networks

Multiparty videoconferencing on multi-drop VP-based SONET/ATM rings: performance analysis

A type of multiparty videoconferencing in VP-based SONET/ATM ring networks under the minimum hop routing rule is analysed. For this type of conference, only the video and voice of the current speaker are broadcast to other conferees. A queueing model is presented. Conference blocking probabilities and video freeze probabilities are derived and are shown to be in close agreement with the simulation results.

EFSM-based continuous media synchronization in multicast networks

As the demands for multicast multimedia applications, e.g., multiparty video conference, increase rapidly, it is urgently required to provide a feasible multicast communication environment and the corresponding multimedia presentation control schemes. In this paper, we propose a Multipoint Multimedia Service Network ( M 3 SN) to achieve multicast multimedia presentations. A M 3 SN consists of a lot of LANs and a WAN. Each LAN is serviced by a multimedia server. The concept of ‘virtual server’ is adopted in M 3 SN. The physical server, which stores media sources that are requested by a group of clients locating in different LANs L i , i = 1… k, multicasts media units to servers of L i . Since servers of L i , i = 1… k, play the role of media relays, i.e., receiving media units from the physical server and then multicasting received media units to the clients that are in L i and request the same media resources, servers of L i are called ‘virtual servers’. Some jitter may occur when media units traverse across the WAN. A virtual server adopts some synchronization control schemes to smooth the occurred jitter. In this way, the clients that are located at the same LAN do not need to deal with the occurred jitter individually. We apply Extended Finite State Machines (EFSM) to formally specify multimedia synchronization in M 3 SN. Based on the EFSM model, intra-medium synchronization is handled by an Actor EFSM; inter-media synchronization is handled by a Synchronizer EFSM. Synchronizer and Actors cooperatively achieve smooth multicast multimedia presentations in M 3 SN.