Transcript Multimedia Data Streaming

Multimedia Over Internet
Growth of Internet
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No production cost
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No inventory to carry
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Low cost infrastructure
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No order processing
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No product shipping
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No customer service concerns
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Make money while you sleep
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The world at your doorstep
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Minimal risk
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High income potential
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No fees for joining or licenses to
buy
Choice of products and services
No sales experience needed
No employees required
No expensive accounts needed
Multimedia Over IP Multicast Network
Multimedia Over IP Multicast Network
Delivering Real-time Multimedia over Internet
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framework for transporting real-time Internet video includes
two components: congestion control and error control
Congestion control consists of rate control, rate-adaptive
encoding, and rate shaping
Error control consists of forward error correction (FEC),
retransmission, error resilience, and error concealment
QoS issues are bandwidth, delays and loss of data
Heterogeneity Network Environment
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Network heterogeneity and Receiver heterogeneity
Network heterogeneity refers to the subnetworks in the
Internet having unevenly distributed resources (e.g.,
processing, bandwidth, storage, and congestion control
policies).
Receiver heterogeneity means that receivers have different
or even varying latency requirements, visual quality
requirements, and/or processing capability.
Heterogeneity Network Environment
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Network-centric approach:
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Routers/switches in the network are required to provide QoS
support to guarantee bandwidth, bounded delay, delay jitter, and
packet loss for video applications (e.g., integrated services, or
differentiated services).
End-system based approach:
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Control techniques to maximize the video quality without any
QoS support from the transport network.
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The integrated solutions is based on both transport (use of
control/processing techniques without regard of the specific
video) and compression perspectives (employing signal
processing techniques with consideration of the video
semantics).
Heterogeneity Network Environment
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Congestion Control:
Bursty loss and excessive delay are caused by network
congestion
Reduce packet loss and delay
Rate control matches the rate of the video stream to the
available network bandwidth.
Rate-adaptive video encoding or rate shaping is required.
Rate control is from the transport perspective, while rateadaptive video encoding is from the compression
perspective; rate shaping is in both transport and
compression domain.
Heterogeneity Network Environment
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Error Control
Four types: Forward error correction (FEC), retransmission,
error resilience, and error concealment.
FEC adds redundant information to a compressed video bit
stream so that the original video can be reconstructed the in
presence of packet loss. Three kinds of FEC:
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channel coding;
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source coding-based FEC;
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joint source/channel coding.
Internet Multimedia Applications
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Classes of multimedia applications
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Streaming Stored Multimedia Data Applications
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One to many streaming of real-time data applications
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Clients request on-demand data (for example, compressed
audio or video files) which is stored on servers.
Similar to ordinary broadcast of radio and television, except
the transmission takes place over the Internet.
Real-time interactive multimedia applications
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Allows people to use audio/video to communicate with each
other in real-time
Multimedia Data Streaming
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Significant improvement over the download-and-play
approach to multimedia file distribution
Allows the data to be delivered to the client as a continuous
flow with minimal delay before playback can begin
Streaming is a server/client technology that allows live or prerecorded data to be broadcast in real time
Multimedia applications such as news, education, training,
entertainment, advertising, and a host of other uses
Streaming enables the Internet or company Intranet as a new
broadcast medium for audio and video.
Multimedia Data Streaming
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Example:
If there are 100 requests for a video stream compressed at
28.8 Kbps,
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the server would require at least a 3 Mbps connection.
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The Encoding Station and the Video Streaming Server can be
one single system.
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However, unless hardware encoding is used, this would
typically be for a situations requiring limited performance (e.g. a
single input stream and a small number of viewer requests).
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Even so, it would still require a fairly high-performance system.
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It is much more common to have two separate systems.
Multimedia Data Streaming
Unicast vs. IP Multicast
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Streaming delivery techniques: Unicast and Multicast.
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Unicast: Computers establish two-way,
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point-to-point connections.
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Client computer can communicate with the computer supplying the
multimedia stream.
Each client that connects to the server receives a separate stream, which
rapidly uses up network bandwidth.
IP Multicast: One computer sends a single copy of the data over the
network and many computers receive that data.
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Only a single copy of the data is sent across the network, which preserves
network bandwidth.
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It is connectionless; clients have no control over the streams they receive
Web Multimedia Information Systems
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Web Process
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Activity
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Organizing entity that determines a set of activities and
specifies their relations
Process step, which participates in the fulfillment of an overall
objective. An agent who satisfies the required skills and rights
(paradigm of role) fulfilled it.
Activities Synchronization
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Temporal preconditions to define a temporal order between
activities, Alternatives to let the user decide on the media to
use for a specific purpose, Parallelism between activities what
is especially useful in the case of collaborative work.
Web Information System Architecture
Interactive Web Pages
Interactive Multimedia Applications
Multimedia Services & Applications
Multimedia Services & Applications
Video Streaming
Interactive Multimedia Applications
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Flexible scheduling based on a finite set of channels available to
all viewers
A set of channels are multicast to all viewers tuned to the
respective channel.
Viewers may watch a program playing on any channel or make a
request for something of their own choosing. Viewers' requests
are scheduled on one of the jukebox's channels using scheduling
criteria like minimum waiting time, etc.
A schedule of currently playing and scheduled programs, updated
in real-time, is available to all viewers. Viewers can watch any
program, including those scheduled by others, by tuning to the
appropriate channel.
Jukebox Policies
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Content-based scheduling
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Service provider scheduling
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Limitations may be imposed based on the content
A service provider may have a desire or obligation to schedule
certain programs at certain times
Limited viewer input
A service provider may want to blunt the ability of individual
viewers to control what programs are playing
Jukebox - Architecture
Jukebox - Architecture
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Scheduling control: The scheduler receivers viewer
requests, performs scheduling, controls the video server,
and provides a schedule of programs to all viewers.
Video server: The video server transmits audio/video
streams into the network
Network: The network must provide an effcient multicast
facility and have sufficient bandwidth to meeting viewer
quality expectations
Receivers: Receivers must be able to receive, decode, and
display an audio/video stream.
Collaborative Work
Collaboration Work
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Client: A client can send some session requests to a session
server to create or join the session so that it can take part in
some meeting.
Media Server: A media server is a RTP Channel for audio
and video communication between clients.
Session Server: The session server is the core of the XGSP,
which can accept request of various clients and organize the
video conference.
Multimedia Messaging System
MMS Network Architecture
MMS Operation
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Sending Messages: A user sends a message by having its MMS-UA
submit the message to its home MMS-RS.
Receiving Messages: Upon reception of a message, the recipient MMSRS verifies the recipient profile and generates a notification to the
recipient MMS-UA.
Message Adaptation: Within a request for delivery of a message, the
recipient MMS-UA can indicate its capabilities, e.g., a list of supported
media types and media formats, for the recipient MMS-RS.t
Delivery Reports: If a delivery report has been requested by the
originator MMS-UA and if the recipient MMS-UA did not request a
delivery report not to be generated, the recipient MMS-RS generates a
delivery report and delivers the delivery report to the originator MMSRS.