Multimedia Communications Spring 2006-07 Shahab Baqai LUMS - - PowerPoint PPT Presentation
CS 584 / CMPE 584 Multimedia Communications Spring 2006-07 Shahab Baqai LUMS Administrative Website http://suraj.lums.edu.pk/~cs584s06 Readings o Multimedia Communications Applications, Networks, Protocols & Standards, Fred
CS 584 / CMPE 584
Spring 2006-07
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– http://suraj.lums.edu.pk/~cs584s06
Standards, Fred Halsall, 2001, Pearson Education Ltd ISBN 81-7808-532-1
networks, K.R. Roa, Zoran S. Bojkovic and Dragorard A. Milanvanovic, Pearson Education Inc. 2002
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– Proposals 5% – Peer Project Reviews 6% – Interim Progress Report 8% – Final Report/ Demo 16%
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Applications:
– non-interactive: net radio and TV, video-on-demand, e-learning, ... – interactive: voice &video conference, interactive TV, tele-medicine, multi-user games, live music, ...
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Large quantities of continuous data Timely and smooth delivery is critical
– deadlines – throughput and response time guarantees
Interactive MM applications require low round-trip delays Need to co-exist with other applications
– must not hog resources
Reconfiguration is a common occurrence
– varying resource requirements
Resources required:
– Processor cycles in workstations – and servers – Network bandwidth (+ latency) – Dedicated memory – Disk bandwidth (for stored media)
At the right time and in the right quantities
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Network phone and audio conferencing
– relatively low bandwidth (~ 64 Kbits/sec), but delay times must be short ( < 250 ms round-trip)
Video on demand services
– High bandwidth (~ 10 Mbits/s), critical deadlines, latency not critical
Simple video conference
– Many high-bandwidth streams to each node (~1.5 Mbits/s each), high bandwidth, low latency ( < 100 ms round-trip), synchronised states.
Music rehearsal and performance facility
– high bandwidth (~1.4 Mbits/s), very low latency (< 100 ms round trip), highly synchronised media (sound and video < 50 ms).
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Late 1960’s - Early 1970’s
– Basic Concepts (Packet Switching etc.) – Resource Sharing --- ARPANET
Mid 1970’s - Mid 1980’s
– LANs – Connectivity
Mid 1980’s - Mid 1990’s
– Internetworking – Global Connectivity
Mid 1990’s ---
– Meeting the needs of Applications
Multimedia Integrated Services
– Taking advantages of advances in technology
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– ubiquity of the Internet – alternative to Telcos – integration with other applications – new functionality
conferencing (made easier) storage (record, play-back, index, edit, integrate…)
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– A picture is worth a thousand word
facial expressions, gestures, reactions…
– Same advantages as with voice communication – Insertion of video clips – Fly-on-the-wall – Quality
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– shared white board
more frequent meetings
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– selectivity (on-line, by profile…) – accessibility without frontiers – urgent notification – linkage among various sources – archival
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– Movie-on-demand (pay-per-view)
large selection full VCR functionality
– Live broadcasts (sports, weddings, …) – Wider audience
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– distance independence
– time-independence
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– Stanford University
Stanford-on-line
– Harvard Business School
– the real-experience – many other benefits
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– criticality – efficiency – productivity – convenience
– Professionals (lawyers, medical doctors)
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Bursty sources Relatively low average data rate per source Full end-to-end reliability is required No latency requirements Mostly point-to-point Traffic pattern is bursty All applications exhibit similar behavior and have similar requirements
– no service differentiation requirement
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Voice traffic is Stream-Oriented
– continuous flow of data – duration of a call is on the order of minute to an hour
Relatively low data rate per stream (2 to 64 Kbps) Some data loss may be tolerated (1 to 2 %)
– clipped segments below 50 ms cause degradation in the form of background noise – larger segments cause intelligibility to be affected
Strict end-to-end latency requirement
– below 150 ms for interactive voice communication
Very low degree of burstiness (silence suppression)
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– 10’s of Kb/sec to 10’s of Mb/sec – data rate depends on content and quality requirement
– interactive communication: 100 ms – one-way broadcast: 1 sec – Video-on-Demand: 1 sec
– content and quality requirement – compression scheme
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Digital Video Data Rates Low quality or talking heads (video conferencing)
– 64 kb/s to 784 kb/s
Business quality (training, video mail)
– 1 Mb/s to 2 Mb/s
Broadcasting quality (NTSC, PAL)
– 4 Mb/s to 8 Mb/s
High-Definition TV
– 20 Mb/s
Studio quality
– 10 Mb/s to 45 Mb/s
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– Videoconferencing (3-4 participants, many-to-many) – group meeting (10’s of participants, one-to-many) – video broadcasting (100’s of participants, one-to-many)
– fixed (closed) predefined set of participants – open set of participants
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– high and low data rates – bursty and stream traffic – real-time and non-real-time traffic – point-to-point and multi-point modes of communications
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Network Infrastructure
– network technologies – network protocols:
routing Multicasting, resource reservations Higher Layer Protocols
– end-to-end data transport protocols – session layer protocols
Media Servers
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– High bandwidth – Guaranteed bandwidth
– Guaranteed maximum end-to-end latency – maximum jitter
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Data Traffic MM Traffic Data Rate
Low High
Traffic Pattern
Brusty Stream Oriented Highly Brusty
Reliability Req.
No Loss Some Loss
Latency Req.
None May be Small
Communication Mode
Point-to-Point Multipoint
Temporal Relationships
None Synchronized Transmission
Type of Service
Single Traffic Type Multiple Types
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– network technologies – network protocols:
Routing Multicasting, resource reservations
– end-to-end data transport protocols – session layer protocols
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Scheduling and resource allocation in most current OS’s divides the resources equally amongst all comers (processes)
– no limit on load – ∴ can’t guarantee throughput or response time
MM and other time-critical applications require resource allocation and scheduling to meet deadlines
– Quality of Service (QoS) management
Admission control: controls demand QoS negotiation: enables applications to negotiate admission and reconfigurations Resource management: guarantees availability of resources for admitted applications
– real-time processor and other resource scheduling
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Typical infrastructure components for multimedia applications
Microphones Camera Screen Window system Codec D B Mixer PC/workstation PC/workstation C Video store Network connections K L M Codec A G Codec H Window system Video file system
: multimedia stream White boxes represent media processing components, many
in software, including: codec: coding/decoding filter mixer: sound-mixing component Component Bandwidth Latency Loss rate Resources required Camera Out: 10 frames/sec, raw video 640x480x16 bits Zero A Codec In: Out: 10 frames/sec, raw video MPEG-1 stream Interactive Low 10 ms CPU each 100 ms; 10 Mbytes RAM B Mixer In: Out: 2 44 kbps audio 1 44 kbps audio Interactive Very low 1 ms CPU each 100 ms; 1 Mbytes RAM H Window system In: Out: various 50 frame/sec framebuffer Interactive Low 5 ms CPU each 100 ms; 5 Mbytes RAM K Network connection In/Out: MPEG-1 stream, approx. 1.5 Mbps Interactive Low 1.5 Mbps, low-loss stream protocol L Network connection In/Out: Audio 44 kbps Interactive Very low 44 kbps, very low-loss stream protocol
PCs
same computers