1.1 Why Is Videoconferencing Necessary For Group

Serverless Multimedia Discussion AssistantHao Wang Xiaozhou Yuan Zhen Tan Lab of Advanced Networking Communications Group Communications GroupElectrical & Computer Electrical & Computer Electrical & ComputerEngineeringDepartment EngineeringDepartment EngineeringDepartment University of British Columbia University of British Columbia University of British Columbia Vancouver, B.C, Canada Vancouver, B.C, Canada Vancouver, B.C, Canada +1 604 765 3865 +1 604 822 5084 +1 604 261 8748hwang@ece.ubc.ca xyuan@ece.ubc.ca tanz@ece.ubc.caABSTRACTServerless Multimedia Discussion Assistant (SMDA) is a unique approach to developing an extensible system for group discussions currently under development by three UBC students. Rather than just giving real-time video and audio, SMDA includes white boarding, instant messaging and even remote control. This system is subject to different design constraints than a typical chatting system or video conferencing system. With SMDA it may be possible to help students to achieve a better performance and minimize the latency thus make our communications easier. In this paper the authors present SMDA approach, and how it can provide assistance to group discussions and improve communication performance. Issues to be resolved in the future and some of the solutions have already been developed are also discussed.Keywords:SMDA, Serverless, Videoconferencing, P2P, Multicast, MPEG-4, GSM.1. INTRODUCTION1.1 Why Is Videoconferencing Necessary For GroupDiscussion?During the learning process, video and audio technology plays a vital role, which can be proved by a prestigious research report.• More than 80 % by sight - of which 20 % is remembered • 11 % by hearing - of which 30 % is remembered• 3.5 % by smell, 1.5 % by touch and taste.Where 50 % of what is both seen and heard is remembered. Further 80 % of what is seen, heard and done, is remembered. It's not enough to just hear words spoken over a telephone -- you need a context, a connection to someone and something. However, the main advantage only appears when every group member is physically present at one place. Videoconferencing can help you differentiate between them. Whether a single wall, building(s), separates you across the state, or even across several continents, videoconferencing is a practical tool for providing the means for groups and individuals to share information spontaneously, compressing both travel-time and distance. Using interactive videoconference equipment reduces the amount of time and money spent in transit to and from meetings. Videoconferencing also reduces the concern for traveling during inclement weather. With videoconferencing, geographically remote people are ableto fully participate in a meeting. Another plus of videoconferencing is that you may include more participants in an interactive videoconference than space may allot for conventional types of meetings, allowing a wider range of representation.Some primary reasons for using videoconferencing and their benefits include:• Time saving: Most videoconferences are two or fewer hours in duration. This means time spentgetting to and from a meeting is often greater thanthe length of the meeting itself.• Cost savings: A one-hour videoconference can cost much less when compared to expensesassociated with travel to short meetings.• Usefulness: Reaches many people at different locations simultaneously.• More timely and frequent communications: When necessary, videoconferencing has allowedmeetings to take place with little advanced noticeand has allowed for shorter, more frequentinteraction.Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise, to republish, to post on servers or to redistribute to lists requires specific permission and/or a fee.HIT2003, Vancouver, BC, CanadaCopyright UBC 2003. 1.2 Why Isn’t Videoconferencing Suitable For Us? According to Salvatore Salamone said in [1] “If you are like most network executives who looked at videoconferencing in the past, you were probably greatlyunder whelmed. Videoconferencing systems were expensive, difficult to set up and use, and required expensive dedicated lines or switched circuits.” to set up a video conference system, we need Product Providers, Communication Network Providers, Application Systems Providers, Service Flat Providers and Content Providers, which usually involve a lot of Internet resources. Other than that, the cost of specific hardware and maintenance is quite considerable. College students can hardly afford this kind of systems for their group discussions. That is where SMDA comes to help. Because SMDA is easy to set up, totally distributed, and highly extensible, those who have high-speed intranet but don’t have high speed Internet access can take full advantage of their local resources thus gain a better performance for real-time video and audio based communications.We evaluated a similar existing system, Microsoft Windows NetMeeting 3.0. We found some performance problems during the distributed meeting. For example, video and audio were asynchronous; and sometimes there were video and audio data packages lost due to network traffic. Because sometimes the speaker’ words and pictures could not be entirely transferred to the receiver, so the quality of the videoconferencing is not desirable.Different from other videoconferencing systems, SMDA only focus on small group discussions. In order to make it a handy tool for students in their discussions, our solution is designed for high-speed intranet which can achieve much better performance while at the same time it also minimize the maintenance cost, administrate overhead and complexity.2 DESIGN2.1 System Design2.1.1 Our Goals• Quality of audio and video• Usability• Reliability• FunctionalityTo achieve these goals, we should take these questions into consider.• What makes SMDA special?• What kind of application do students really need for their group discussion?• What are the best options for sharing data between remote parties along with some tips formaking data sharing easier to do?• Which hardware/software should we support?• What characteristics should software scheduling and monitoring systems have in order to make iteasy to monitor and use the videoconferencingsystem?2.1.2 Characteristics• ServerlessFor simplicity, SMDA should be easy to setupand totally distributed without single point offailure. We use P2P technology to make SMDA adistributed system.• Low latency Multicasting [2]To decrease the blocking rate and increasenetwork utility, our routing mechanism is basedon “alternate path multicast (APM) protocol”. [3]• Reliable compression and transmission MPEG4We chose MPEG-4 because it provides losslessvideo and audio compression and transmission.Other than that, its relative simplicity andavailability of high-performance freely availablesoftware decoders also very suitable for thissystem.• Software solutionsWe chose to perform MPEG-4 decoding insoftware to make our solution ubiquitous andindependent of specialized hardware. Therationale behind this is that most students don’thave professional hardware decoder.• Open source.In order to extend the system for further use, weprefer to share and use freely available codewherever possible.2.1.3 Key Components• Video Capturing system using Window Multimedia in Platform SDK.• Audio Capturing system using Direct Sound.• MPEG-4 Video Stream using Microsoft MPEG-4 CODEC and VCM.• GSM6.10 Voice Stream using Microsoft GSM6.10 CODEC and ACM.• P2P Video and Audio Stream Delivering system.• P2P File sharing system.• P2P chatting system.2.2 Key Technologies2.2.1 MPEG-4The MPEG group officially started a new MPEG-4 standardization from 1994 with the mandate [4] to standardize algorithms and tools for coding and flexible representation of audio-visual data to meet the challenges of future Multimedia applications and applications requirements. The standard views multimedia scene as a collection of objects. These objects can be visual, such as background, or sound, such as speech and so on. Each of these objects can be coded independently using differenttechniques to generate separate elementary bit streams. These bit streams are multiplexed along with a scene description.A block diagram for the basic video-coding algorithm is shown in Figure 1. The shape coding is a major part of the algorithm. The different objects that make up the scene are coded and sent to the multiplexer. The information about the presence of these objects is also provided to the motion compensated predictor, which can use object-based motion compensation algorithms to improve the compression efficiency. What is left after the prediction can be transmitted using DCT based coder.The MPEG-4 video coding standard will provide an "object layered" bit stream to assist "content-based" functionality. Each object is coded into a separate object bit stream layer. The shape and transparency of the object - as well as the spatial coordinates and additional parameters describing scales and location, such as object zoom, rotation, and translation or related - are included in the bit stream. The user can either reconstruct the original sequence in its entity, by decoding all "object layers" and by displaying the objects at original sizes and scales and at the original location.2.2.2 GSM 6.10The GSM 6.10 is the method of speech data compression used in telephony or voice messaging service and also used in the GSM mobile telephone system in Europe and North America . [5]To digitally represent a sound wave, we have to sample and quantize it. The sampling frequency must be at least over Nyquist frequency. Speech signals, whose interesting frequencies go up to 4 kHz, are often sampled at 8 kHz and quantized on either a linear or logarithmic scale.The input to GSM 6.10 consists of frames of 160 signed, 13-bit linear PCM values sampled at 8 kHz. One frame covers 20 ms, about one glottal period for someone with a very low voice, or ten for a very high voice. This is a veryshort time, during which a speech wave does not change too much. The processing time plus the frame size of an algorithm determines the "transcoding delay" of communication. The encoder compresses an input frame of 160 samples to one frame of 260 bits. One second of speech turns into 1625 bytes; a megabyte of compressed data holds a little more than ten minutes of speech. The GSM 6.10 compressor models the human-speech system with two filters and an initial excitation. The linear-predictive short-term filter, which is the first stage of compression and the last during decompression, assumes the role of the vocal and nasal tract. It is excited by the output of a long-term predictive (LTP) filter that turns its input--the residual pulse excitation (RPE)--into a mixture of glottal wave and voiceless noise.2.2.3 P2PP2P (Peer to Peer) is one of communication methods that allow sharing computer resources with other computers. P2P revolution starting from the success of Napster makes P2P consortium participated in by several big companies IBM, Intel, and etc active players. For more information, please refer to [6]. Because it is designed for distributed applications, SMDA is based on P2P.2.2.4 Low Latency MulticastingThe fundamental principle we decide to use multicasting instead of unicasting is because of its efficient handling of group communications within an IP network. Multicasting extends a single line of communication (normally called the “data stream”) over a network, allowing those users who wish to participate in the data stream activity to do so (if they belong to a specific multicast group). In this configuration, each connection does not require new bandwidth to be consumed; rather, each user connects to the single data stream. The net result is a far more efficient use of network bandwidth for group communications. This can be approved by figure 2.Figure 2: Comparison of unicast and multicast.Alternate Path Routing is a routing technique where multiple paths, rather than just the shortest path, between a source and a destination are utilized to route traffic. One of the objectives of alternate path routing is to distribute load among multiple paths in the network. For path installation, we design a receiver-oriented alternate path protocol and prove that it recon-figures multicast trees without introducing loops. For path computation, we propose a scalable local search heuristic that allows receivers to find alternate paths using only partial network information. According to the simulation study of the inventor, APM could do local search to find alternate paths approximately as well as a link-state protocol, with much lower overhead.All users in the conference are able to host a group discussion. Assuming Hao wants to host a discussion and want to get XiaoZhou and Zhen involved. He just needs to invite XiaoZhou and Zhen by letting them know his IP and they can join/leave the discussion as easy as clicking a button.2.4 User Interface Design• ‘Mirror’ Image – Individuals can see how theyappear to others.• Group connectivity – Create ‘Groups’ under asingle title in the Address Book and by dragging the ‘title’ into the ‘On Call’ window and clicking the ‘Call’ button you will automatically connect to all.• Notepad – Data changes automatically as youmove click on a name or video screen. Type notes that can be subsequently printed erased or edited, either during or outside of a conference. • White boarding – All participants can contributeto Whiteboard content, which can be seen in real-time by all and subsequently printed across multiple pages if desired.•Real Time File Transfer – For content that could not be forwarded in advance, this facility provides a means of propagating any new material to all users for simultaneous review.•Easy use menu – A double-click on the name of the person in the Address Book who you wish to contact gives connection to any PC worldwide. Alternatively, ‘drag & drop’ their name into the ‘On Call’ window.•‘Undock’ video and other windows – Move video images, address book, notepad, agenda, slideshow, whiteboard, etc and display at whatever size you want.Figure 4: A screen shot of the user interface of SMDA.2.5 A Real ScenarioParticipants: Hao, Zhen, and Xiaozhou.Location:Hao: do some research at the main libraryZhen: enjoy the sunshine at the beach with his laptop (with wireless coverage)XiaoZhou: work on her assignment at EECE lab Purpose: Discuss their final projectProcedures:1. Xiaozhou hosts this meeting, Zhen and Hao first find out her name in the address book and click it, After a sec, Three available rooms show up on the screen, which are SUB, Starbuck’s and Stanley Park.2. As usual, Hao double clicks “SUB” room to get in. 2 people are already there waiting for him, busy chatting and making fun of each other. Now, it is the time to start our discussion.3. Before we get started, Zhen first share the latest version of our conference paper by transferring the file by SMDA to us and then we open up a white board to express our own opinion. After an hour’s discussion, we finally come up with a detailed plan and now everybody knows exactly what they are going to do. Other than that, we set up a timefor our next discussion, which is just 24 hours later. By that time, Hao will host the meeting and we will meet at “Startbuck’s”.3 IMPLEMENTATION3.1 OverviewThe implementation of SMDA consists of a software video codec, a software speech codec, data transport protocols, control protocol and multiplexing protocol.3.2 ProtocolsIn general, SMDA includes SMDA UI and SMDA daemon. SMDA daemon can work as either a host or a guest. Host daemon need to manage all guest SMDA and calculate the shortest routing path. Host SMDA daemon uses port 7461 and 7462 to receive video and audio data from guest SMDA daemon. Guest SMDA uses 7463 and 7464 to send out video and audio data. Other than that, Host SMDA daemon reserves port 4433 to multiplex shared application data such as file sharing.3.2.1 Data Transport ProtocolSMDA supports both TCP and UDP .For real-time video/audio; SMDA daemon uses UDP to transfer data among all participants. For other loss-sensitive shared application such as file transferring and white boarding, we use TCP as transport protocol.3.2.2Control ProtocolSMDA requires all participates to set up a permanent connection between guest and host. All control messages are sent to port 443 of the Host daemon. Basically, our control protocol is a request-reply protocol.3.2.3 Multiplexing ProtocolMultiplexing protocol is designed for shared applications such as file transfer and white boarding. With this protocol, Host can easily redirect data stream to different guests with an optimized routing protocol.4 EVALUATION4.1 Evaluation Criteria:Is Serverless Multimedia Discussion Assistant a useful and useable system? To ensure that SMDA is a system that users will find useful and useable, we have developed the following evaluation criteria. Some of criteria are based on the HCI, while others are based on the function of the system [8].4.1.1FunctionalityWhether our system can provide enough functions to meet the needs of students in group discussion. 4.1.2 UsabilityLots of videoconferencing systems require high bandwidth, so they have limitations of using. Our system should perform our desired task efficiently well in campus environment.• To determine whether SMDA can provide a communication environment for students in groupdiscussion• To determine whether SMDA can provide high performance to allow users to effectivelycommunicate each other.4.2 Evaluation Scheme For Our SystemSubject: Four UBC students who participated in previous tests. The reason we choose 4 subjects is because single users achieve poor results, only find 35% of usability problems, but 4 evaluators can find 75% of usability problems.We proposed two procedures to evaluate our system:4.2.1 Procedure One: Heuristic evaluation4.2.1.1 MethodIn this process, we required the students to go through the SMDA system design several times to inspect various design elements. Identifying design flaws which we should fix or redesign. Each member independently checked for compliance with evaluation criteria.The students first to get feel for flow and scope of the system, if SMDA has enough function, audio, video, whiteboard, chat, sharing programs. Second to focus on specific elements, and compared with list of evaluation criteria, consider other principles/results those come to mind. We also required the users to record the operation violation, since that may be a point, which we should fix, or redesign.4.2.1.2 Result of procedure oneSubjects feedback shows that due to the limitations of the network connection, the quality of most of the videoconferencing is not desirable. The bandwidth requirement of our system design is relatively low, so that the communication performance of our system can be highly improved.The functions provided in our system include:• Audio• Video• File Transfer• Chat• Sharing ProgramsThe interviewers’ feedback shows that the functionality of our system could meet most users’ requirement. Compared with Microsoft NetMeeting 3.0, our system supports multi-users. The most important thing is our SMDA is aserverless system; Students loved it because they felt that everything was totally under control. —Server could be itself! Setting up a conference is as easy as click a shortcut on the desktop. Feedback shows that Recording is not so popular. One student said that nobody would use recording, they’d rather find another time to set up a discussion. So we got rid of the recording from our design. The interviewer’s feedback also shows that the students prefer SMDA, because it is much cheaper than most of other current videoconferencing products.The students indicated that our user interface design is clear and understandable. Most of the menu design met the evaluation criteria, which was easy to learn and easy to use. However, some problems were found in the evaluation. For example, our current design only supports at most 6 persons at a time; some buttons of the menu didn’t show its function clearly, etc. We revised our design in the later system prototype.4.2.2Procedure Two: User test of the SMDA system prototype—compare to Microsoft Windows NetMeeting 3.0 The objectives of user test of the SMDA system prototype • To determine whether SMDA system has good performance for group discussion.• To determine whether SMDA system has good reliability for group discussion.Participants: 4 UBC students.Location: comm. lab at UBCMethod:The criterias used in our evaluation of performance and reliability include:• Did users encounter any problems of connection on the first try?• Were files able to be sent and received on the first try?• Were videoconferences established effectively during the first experience?Task 1. Interview. Ask subjects the following questions about videoconferencing system background information1. Have you used any videoconferencing system forgroup discussion? If yes, do you prefer usingvideo conferencing system than telephone?2. Do you find difficult or frustrating to use videoconferencing systems? Why or why not?Task 2. Microsoft Windows NetMeeting 3.0 testing. Because NetMeeting only supports at most 2 users in each meeting, two groups were formed. Each group had two subjects, and performed the following steps. Observations were made and system designers took notes during the testing.Step1. System trainingStep2. Establish connectionStep3. Perform a 10 minutes videoconferenceStep4. Transfer a 5 MB fileStep5. Exit the systemTask 3. SMDA system testing. Because SMDA system can support up to 6 users meeting at the same time, in this test we formed one group consisting of all 4 subjects for group discussion. Each subject performed the following steps in the test. Observations were made and system designers took notes during the testing.Step1. System trainingStep2. Establish connectionStep3. Perform a 10 minutes videoconferenceStep4. Transfer a 5 MB fileStep5. Exit the systemTask 4. Questionnaire. Give each subject a questionnaire immediately after completing the SMDA system test. Questions in questionnaire are as follows: Questionnaire:1. How many times did you try for a successfulconnection in using NetMeeting for groupdiscussion?2. How many times did you try for a successfulconnection in using SMDA for group discussion?3. What do you think of the performance of videoand audio synchronization when usingNetMeeting?4. What do you think of the performance of videoand audio synchronization when using SMDA?5. What do you think of the performance of latencywhen using NetMeeting?6. What do you think of the performance of latencywhen using SMDA?7. How many times the connection dropped duringthe 10-minute call in using NetMeeting?8. How many times the connection dropped duringthe 10-minute call in using SMDA?9. Do you think SMDA increased your participationin group discussion?10. A typical videoconferencing client usually costaround $300/month. Provided SMDA asks for thesame price. If you are asked to choose one forstudents’ group discussion, will you chooseSMDA?Result of Procedure TwoAll subjects indicated that they had experience on using videoconferencing system, but most of them did not want to use it for school discussion. Because the performance of many videoconferencing systems is not satisfied, they could not stand the latency and asynchronous of video and audio. Some of them even cut the video off in order to get better audio performance.The questionnaire and observation results of NetMeeting and SMDA tests are shown in Table 1.Microsoft NetMeeting 3.0SMDAMaximum numberof users 2 6Times tried for a successful connection 2.5 1 Performance of video and audio synchronization average good Latency average good Number of drops in 10 minutes 1 0 Time used for transferring a 5M file 1 1 Economic factor Free software Open sourcedTable 1: Results of evaluation procedure two.The results show that, compared to NetMeeting, SMDAsystem has improved the network latency and has soundreliability, our SMDA system supports up to 6 users at thesame time, and allows students to effectively communicateeach other.5 SUMMARYWe designed and implemented a videoconference systemfor our project. First, we conducted a background researchon videoconferencing systems and evaluated a currentvideoconferencing system- Microsoft NetMeeting 3.0. Wefound that NetMeeting 3.0 had network latency problemand reliability problem. Moreover, it only supports 2 usersat a time at the most. Our SMDA system uses “Serverless”structure in order to improve the performance andreliability. We had a heuristic evaluation to our designscheme, and then we implemented a prototype of SMDA.In the system user testing, we compared our SMDA systemprototype to Microsoft Windows NetMeeting 3.0. Theresults show that our SMDA system has improved thenetwork latency and has sound reliability.6 FUTURE WORK • ClientlessWe plan to make SMDA daemon into a plug-in, In that case, Setting up a video discussion would be as easy as visiting a website and all the UI will be browser based. • PDA supportWith PDA support, SMDA will be very popular. So far, there is no videoconferencing software provides PDA support. • QoSSMDA can be enhanced with RSVP [7] component, and will be instrumented to measure end-to-end performance of QoS attributes such as bandwidth, latency, packet loss and jitter.7 INFORMATION AND QUESTIONS For more information, contact{hwang,xyuan,tanz}@ece.ubc.ca.ACKNOWLEDGEMENT We thank Dr. Sidney Fels for his creative instruction and generous support. Without him, this project can’t be done.We also thank Dr. Lee Iverson for his valuable feedbacksand those UBC students who participated in the evaluation.REFERENCES [1] Salvatore Salamone Network World, 09/24/0 “Time for videoconferencing”[2] W.A. Adamson, C.J. Antonelli, K.W. Coffman P.McDaniel J. Rees “Secure Distributed Virtual Conferencing: Multicast or Bust” CITI Technical Report 99-1 [3] D. Zappala, Alternate Path Routing for Multicast. IEEE Infocom 2000, March 2000 [4] http://wwwam.hhi.de/mpeg-video/#MPEG4 [5] Khalid Sayood, Introduction to Data Compression, Morgan Kaufmann, 2000 [6] Thomas C. Schmidt, Matthias Wählisch “Global Serverless Video Conferencing over IP ” [7] R. Braden and L. Zhang, ‘‘Resource ReSer- Vation Protocol(RSVP) -- Version 1 Message Processing Rules,’’ in IETF RFC 2209 (1997). [8] Samuel R. Collins, Steve L. Ferenci, Antonio Haro, Matthew J. Moyer (2000) A visual and auditory information enhancement system for automobile navigation。