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Fig. 1. Virtual classroom application characteristics. Sachin G. Deshpande, Member, IEEE, and Jeng-Neng Hwang, Fellow, IEEE those from RealNetworks [10], Microsoft Netshow 11], and Microsoft V xtreme [12]. The majority of services and products in this category allow a one-way real-time streaming broadcast of live contents (classes or lecture talks for the distance learning systems) or on-demand streaming of the stored contents. On the other hand there are various video phones, video con: ferencing and Internet meeting softwares in the market, including Intel Video Phone [13], White Pine’s Enhanced CU-SEEME [14], Meeting Point, and Microsoft NetMeeting [15] whic h support real-time interactive two-way or multiway communications. With affordable audio, video capture cards and cameras, the progress in low bit-rate coding, and the so-called x2 te chnology [16], the home users can participate in a video (and audio) con- ference at 56 Kb/s or lower. The next step is to combine these two types of services and provide a virtual distance learning classroom which is interactive [17]-[21] (see Fig. 1). The live class interaction or talk will be streamed (unicast/multicast) to remote sites where students can participate by being able to ask questions in real-time, under the control of a central multipoint control unit (MCU). Another mode is allowing students to view the recorded lecture in real-time and ask questions to the instructor or a teaching assistant during office hours.

Figure 1 Virtual classroom application characteristics. Sachin G. Deshpande, Member, IEEE, and Jeng-Neng Hwang, Fellow, IEEE those from RealNetworks [10], Microsoft Netshow 11], and Microsoft V xtreme [12]. The majority of services and products in this category allow a one-way real-time streaming broadcast of live contents (classes or lecture talks for the distance learning systems) or on-demand streaming of the stored contents. On the other hand there are various video phones, video con: ferencing and Internet meeting softwares in the market, including Intel Video Phone [13], White Pine’s Enhanced CU-SEEME [14], Meeting Point, and Microsoft NetMeeting [15] whic h support real-time interactive two-way or multiway communications. With affordable audio, video capture cards and cameras, the progress in low bit-rate coding, and the so-called x2 te chnology [16], the home users can participate in a video (and audio) con- ference at 56 Kb/s or lower. The next step is to combine these two types of services and provide a virtual distance learning classroom which is interactive [17]-[21] (see Fig. 1). The live class interaction or talk will be streamed (unicast/multicast) to remote sites where students can participate by being able to ask questions in real-time, under the control of a central multipoint control unit (MCU). Another mode is allowing students to view the recorded lecture in real-time and ask questions to the instructor or a teaching assistant during office hours.

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Fig. 2. Virtual classroom interactive distance learning environment.
Fig. 2. Virtual classroom interactive distance learning environment.
Fig. 3. Virtual classroom live class server: (a) instructor's video and (b) remote student's video during question time. these electronic slides as a video using the low bit-rate video coding standards is not effective. Also, the instructor typically pans or zooms in on the slide to give students a better view. This results in a lot of wasted bits when the slides are encoded as a video sequence. The solution to this is to send the original electronic slide to the client machine only once in the original available electronic format.
Fig. 3. Virtual classroom live class server: (a) instructor's video and (b) remote student's video during question time. these electronic slides as a video using the low bit-rate video coding standards is not effective. Also, the instructor typically pans or zooms in on the slide to give students a better view. This results in a lot of wasted bits when the slides are encoded as a video sequence. The solution to this is to send the original electronic slide to the client machine only once in the original available electronic format.
Fig. 4. Virtual classroom client: (a) instructor's video and (b) remote student’s video during question time.
Fig. 4. Virtual classroom client: (a) instructor's video and (b) remote student’s video during question time.
Fig. 5. Virtual classroom multipoint control unit screen shot.
Fig. 5. Virtual classroom multipoint control unit screen shot.
Fig. 6. Various scenarios: (a) multicast LCS: instructor's media; (b) multicast LCS: multicast client’s media during question time; (c) multicast LCS: unicast client’s media during question time; (d) unicast LCS: instructor’s media; (e) unicast LCS: multicast client’s media during question time; and (f) unicast LCS: unicast client’s media during question time.
Fig. 6. Various scenarios: (a) multicast LCS: instructor's media; (b) multicast LCS: multicast client’s media during question time; (c) multicast LCS: unicast client’s media during question time; (d) unicast LCS: instructor’s media; (e) unicast LCS: multicast client’s media during question time; and (f) unicast LCS: unicast client’s media during question time.
Fig. 7. Slide presenter server.
Fig. 7. Slide presenter server.
Fig. 9. Slide presentation system: possible architectures. Fig. 10. Recorded SMIL presentation playing in a RealPlayer G2. The next two subsections will explain the role of various fields in the packet header.
Fig. 9. Slide presentation system: possible architectures. Fig. 10. Recorded SMIL presentation playing in a RealPlayer G2. The next two subsections will explain the role of various fields in the packet header.
All of the other fields of the RTP header are filled in as de- tailed in [38].
All of the other fields of the RTP header are filled in as de- tailed in [38].
Fig. 11. (a), (d), and (g): uncompressed video frames; (b), (e), and (h): H.263 (+) compressed video frames (bit-rate = 36 Kb/s); (c), (f), and (i): proposed method used to compress the video frames (bit-rate = 36 Kb/s). Fig. 12. Distribution of handwritten video and the video of instructor or students’ face against time in a typical 50 min class.
Fig. 11. (a), (d), and (g): uncompressed video frames; (b), (e), and (h): H.263 (+) compressed video frames (bit-rate = 36 Kb/s); (c), (f), and (i): proposed method used to compress the video frames (bit-rate = 36 Kb/s). Fig. 12. Distribution of handwritten video and the video of instructor or students’ face against time in a typical 50 min class.
Fig. 14. Structure of aJBIG compressed bilevel video packet. Fig. 13. System to handle handwritten video in a live class: (a) encoder and (b) decoder.
Fig. 14. Structure of aJBIG compressed bilevel video packet. Fig. 13. System to handle handwritten video in a live class: (a) encoder and (b) decoder.
Fig. 15. Fields in the JBIG bilevel video header.
Fig. 15. Fields in the JBIG bilevel video header.
fees he SUBJECTIVE TEST RESULTS FOR INTRA-MEDIA QUALITY ASSESSMENT
fees he SUBJECTIVE TEST RESULTS FOR INTRA-MEDIA QUALITY ASSESSMENT
Fig. 16. SlideWizard: automatic web page and SMIL presentation creation tool in action.
Fig. 16. SlideWizard: automatic web page and SMIL presentation creation tool in action.
SUBJECTIVE TEST RESULTS FOR INTER-MEDIA AND OVERALL ASSESSMENT
SUBJECTIVE TEST RESULTS FOR INTER-MEDIA AND OVERALL ASSESSMENT
afAaiaei 4a SUBJECTIVE REST RESULTS FOR ASSESSMENT AGAINST KNOWN CODEC IMPAIRMENTS
afAaiaei 4a SUBJECTIVE REST RESULTS FOR ASSESSMENT AGAINST KNOWN CODEC IMPAIRMENTS
Related topics:
EngineeringEducational TechnologyVideo CodingVideo CompressionReal Time SystemsVirtual ClassroomVideo on DemandSynchronized Multimedia Integration Language
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