HD video in teaching environment
Eva Hladká, Ludek Matyska
CESNET, Prague, and
Masaryk University, Brno
Czech Republic
Overview
• Two Collaborative Concepts
• Virtual Classroom Concept
• Collaborative Technologies
– HD Video
• Introduction to HPC class
– Participating institutions
– Network setup
– Site Setup
• Time-Shift Problem and its Mitigation
• Lessons Learned
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2007
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Two Collaborative Concepts
• “In” and “Out”
– “In” – collaborate in a virtual world (on line
games, Second Life etc.)
• System (virtual world) explicit and important
part
– “Out” – bridge the physical distance
(classical videoconferences)
• Invisible system
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2007
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The Learning Process
• The teacher as the focal point
– Verbal expression
– Non-verbal expression
– Empathy, …
• We should not “hide” the teacher
• Virtual classroom – implementation of
the “Out” concept
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2007
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Virtual Classroom Concept
• “In” concept: strictly digital classroom, avatars
• “Out” concept: several physical classrooms
sharing one teacher
• The problem:
– To make teacher’s presence as natural as possible in
all “instances”
• Use of advanced collaborative technologies
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2007
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Collaborative Environment
• High Definition (HD) Video
– High picture quality
– Able to record and display classical screen without
any distortion
– Both a screen/blackboard and a teacher as seen
in a single classroom
• Huge amount of data, difficult to process
(compress/decompress) in real time
– Use of uncompressed video
– Accompanied with uncompressed audio
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2007
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HD Video Formats
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2007
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HD Video Parameters Used
• Basic parameters
– Effective resolution 1920x1080 pixels
– 60 interlaced fields per second
– 4:2:2 color space sampling with 10b per color
plane
• Packetizing
– 8500 B Jumbo Ethernet frames
– Data rate of 1.5 Gbps one stream
• Processing: UltraGrid software
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2007
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Actual Class Taught
• Introduction to High Performance Computing
– Prof. Thomas Sterling, LSU, LA, USA
• Five participating institutions
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Masaryk University, Czech Republic (Europe)
University of Arkansas
Louisiana Technical University
MCNC, North Carolina
North Carolina State University
• Spring semester 2007 (January till June)
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Data Distribution
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Data Distribution II
• Based on a set of packet reflectors
– Located in appropriate places in the network
– Create a logical overlay network
• Used instead of Multicast (higher reliability)
• Minimizing the data actually transmitted over
any physical link
• 1:N and N:1 video distribution
– Only teach sees everybody
• N:N audio distribution
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Data Distribution III
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Site Setup
• HD camera
– Plus processing hardware/software
• Only LSU (Johnston) needed several
projection screens
– LCD/Plasma or full HD projectors
• Stream capture (MU)
– RAID0 disk array (needs >200MB/s)
– 1TB per 1.5hour lecture
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2007
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Audio
• Using RAT from MBone Tools
• Uncompressed stream
– 16 b quantization, 48 kHz sampling rate
– Data rate 1.6 Mbps
– N:N distribution
• Most important—the microphone quality
– Changes several times during the semester
• Bad audio could cancel the lecture
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LSU Setup
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MU Web Pages (Materials)
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MU Web Pages (Videos)
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Problems
• Time-shift problem
– Different time zones
– Different beginnings of a semester
• Actual interaction among different students’
groups
• Problem sets and homework
– Similar environment is necessary
• Computing cluster, high performance network, batch
system, compilers, …
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2007
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Time Shift Mitigation
• Different time zones
– Negotiations
• Did not work for this case
• LSU started at 3pm  MU at 10pm
– With truly global collaboration always somebody
“out of usual working hours”
• Different start of a semester
– Those starting later must catch the delay
• Necessity—access to stored lectures
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2007
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Time Shift Mitigation II
• MU started to capture HD video stream when
the lectures at LSU started
– TA time intensive, twice a week, 10pm till midnight
• Students agreed to watch more than two
lectures per week
– However, problem with homework
• Hints in “future” lectures
• Lesser time available (overlap of problem sets)
• Actual lectures started at 7pm
– When delay removed, students invited to stay for
the real time lectures
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2007
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Lessons Learned
• Lot of manual work
– Setting/tearing networks
– Both recording time and the re-play
– Setting local environment and adapting
problem sets to it
– Sharing the evaluation process (points)
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2007
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Lessons Learned II
• Adaptation to problems
– Not so hot for recorded lectures
– Real time adaptation very difficult
• We run a back up solution using AccessGrid and
Webcasting in Quick Time format
• Need to develop more detailed monitoring of
the network and automatic reaction to any
problems (including change of the
collaborative environment)
– See CoUniverse information sheet
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2007
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Lessons Learned III
• Students and teacher interaction
– Must be directly incorporated in the
materials
• Interactive feedback required
– Some mitigation for delayed groups
– Problem sets to be solved by group of
students (from different institutions)
• General enough not to be thwarted by the time
shift (esp. different start of semester)
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2007
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Conclusion
• The Introduction to HPC class ran during the
Spring semester 2007
– Using collaborative environment based on
uncompressed HD video and audio
• At 5 institutions, almost 100 students
attended and passed the class
– Including all the homework, projects, …
• We plan to repeat the experience next Spring
for some 15 institutions round the globe
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2007
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Thank you for your attention
Questions?
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2007
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