Transcript MMN-lec20-MultimediaApplications

Multimedia Applications
Instructor: Hamid R. Rabiee
Spring 2013
Outline
1.
2.
Digital TV
3. IPTV
 Introduction to MHP
 Introduction to IPTV
 DVB
 Key features
 MHP
 IPTV components
Voice Over IP
4. Multimedia Conferencing
 Introduction to VOIP
 Introduction to Multimedia Conferencing
 Challenges of VOIP
 Multimedia Conferencing Components
 IP telephony
 Types of Multimedia Conferencing
 Communication in various network
topologies
2
Digital Media Lab - Sharif University of Technology
Digital TV
Why digital TV?
 Better image quality
 More channels
 Multiple audio channels
 Subtitles
 The whole new world of services
4
Digital Media Lab - Sharif University of Technology
Digital TV Standards
 Digital Video Broadcasting (DVB)
 Satellite transmission standard (DVB-S)
 Cable standard (DVB-C)
 Terrestrial broadcast services standard (DVB-T)
 Multimedia Home Platform standard (MHP)
 Advanced Television Systems Committee (ATSC)
 Terrestrial digital broadcasting standard (ATSC-T)
 Cable distribution standard (ATSC-C)
 Integrated Services Digital Broadcasting (ISDB)
 Satellite broadcasting standard (ISDB-S)
 Cable standard (ISDB-C) for cable TV networks
Appendix A
 Terrestrial digital broadcasting standard (ISDB-T)
 Terrestrial Sound Broadcasting (ISDB-TSB) for terrestrial broadcasting
5
Digital Media Lab - Sharif University of Technology
Voice Over IP (VOIP)
Introduction to VOIP
 What is VOIP?
 VoIP is the ability to make telephone calls and send faxes over IP-based data networks with a
suitable quality of service and superior cost/benefit.
 VOIP Components
 Servers : For processing IP calls and manage interaction with PBX etc.
 End-point devices such as phones
 Media and VoIP gateways
 IP network
 Why VOIP?
 Demand for Multimedia communication
 Demand for integration of Voice and Data networks
 Cost Reduction in long distance telephone calls
 How VoIP works




Continuously sample audio
Convert each sample to digital form
Send digitized stream across Internet in packets
Convert the stream back to analog for playback
 Challenge
 Voice transmission delay
 Call setup: call establishment, call termination, etc.
 Backward compatibility with existing PSTN (Public Switched Telephone Network)
7
Digital Media Lab - Sharif University of Technology
Origins of VOIP
 Internet Telephony software for multimedia PCs (1995)
 Users frustrated by poor QoS, difficulty of use, lack of interoperability
 Standards are critical for success
 Coding/decoding (codec) between analog voice and digital packets
 Locating the party you want to call
 Signaling to set up, modify, tear down the voice call
 Access to vertical services (call forwarding, 3-way calling, …)
 Gateways to PSTN
 Media routing, quality of service (QoS) left to other IP mechanisms (not
VoIP-specific)
8
Digital Media Lab - Sharif University of Technology
VOIP: Goals and Benefits
 Consolidation of voice, data on a single network
 Simplify infrastructure, operations; provide bundled services
 Support for intelligent terminals as well as phones
 Increased flexibility
 Multiple bit rates, multiple media types, richer signaling
 Distinguish calls from connections (add/modify streams during call)
 Separation of service control from switching/routing
 Accelerate new service development, increase end-user control, evolve from
VoIP towards advanced services
 Expansion of competition
9
Digital Media Lab - Sharif University of Technology
Voice To/From IP
Network
Digital
Analog
Voice
CODEC: Analog to Digital
Process Header
Compress
Re-sequence and
Buffer Delay
Create Voice Datagram
Decompress
Add Header
(RTP, UDP, IP, etc)
CODEC: Digital
to Analog
Analog
Digital
Voice
10
Digital Media Lab - Sharif University of Technology
Network
NGN Architecture (Next-Generation Network)
 Oriented towards application of VoIP (or VoATM) to large-scale
public networks
 Focus on scalability, network control, support for traditional phones,
sophisticated gateway (GW) to the PSTN and its services
 Media GW interfaces voice stream to PSTN trunk or phone line
 Signaling GW allows signaling directly to SS7 network
 Softswitch controls Media GWs and does call processing
 Allows smaller, cheaper Media GWs (e.g., for individual homes)
 Control via MGCP (Media Gateway Control Protocol) or H.248
11
Digital Media Lab - Sharif University of Technology
NGN Example
Voice over DSL or Cable Modem
NGN
PSTN
Softswitch
SCP
IP Phones,
PCs
SS7
Gateway
Customer
Gateway
DSL or
PacketCable
Access
Core Packet
Network
Voice Streams
Trunk
Gateway
Class 5
Switch
Can also use to interconnect PSTN clouds (long-distance),
or PSTN switches (interoffice backbone)
12
Digital Media Lab - Sharif University of Technology
SS7
Signaling
Network
Challenges of VOIP
 Latency
 Latency is the time taken for a packet to arrive at its destination
 Packet switching overhead
 Congestion
 Latency may result in voice synchronization problems
 Jitter
 Jitter is the delay experienced in receiving a packet when a packet is expected to
arrive at the end point at a certain time
 Bandwidth
 When bandwidth is shared between voice and computer data, certain bandwidth may
have to be allocated for voice communication on a network
 Packet loss
 Packet loss in unavoidable
 It can be minimally tolerated in voice transmission
 It should not, in the first place, distort the audio
 Reliability
 Because the computer network is used, the reliability of the network will have an
impact on the telephony service
 In the analog telephone industry, reliability of 99.999 percent uptime is required
 The above is known as five nines
 VoIP networks can achieve over 98 percent reliability ?
13
Digital Media Lab - Sharif University of Technology
Challenges of VOIP (cont.)

More in
Appendix
Scalability
 Ability to add more telephony equipment as the company grows
 Network bandwidth and other issues may have an effect on scalabilityB
 Security
 As VoIP uses the Internet, for example, it is vulnerable to the same type as security risks
 Hacking
 Denial of service
 Eavesdropping
 Features
 IP telephony need to match and, in the long run, exceed the features provided by the
PSTN
 Call waiting
 Three way calling etc.
 Interoperability
 IP telephony equipment manufactured by different vendors must be able to talk to
each other
 Standardized protocols are needed
 Switch over cost
 The cost of migrating from legacy PBX to IP PBX
14
Digital Media Lab - Sharif University of Technology
IP Telephony
in Appendix C
Enterprise VoIP
Location B
Location A
PSTN
Centrex
or PBX
Core IP
Network
IP PBX
GW
GW
Softswitch
IP
phone
IP
phone
Many possible combinations of VoIP and circuit-switched telephony
15
Digital Media Lab - Sharif University of Technology
IPTV
Introduction to IPTV
Internet Protocol Television (IPTV)
 IPTV (Internet Protocol television): the delivery of programming by video stream
encoded as a series of IP packets.
 IPTV can be free or fee-based and can deliver either live TV or stored video to the
Television one addressed program at a time
 Traditional Pay-Television: all programming is broadcast simultaneously and is
available by tuning to the channel.
IPTV and Internet TV
IPTV delivered to TV set, not PC
IPTV is provided by a few large telecom providers
Internet TV: anyone can create an endpoint and publish that on a global basis.
(YouTube)
They are competitors
17
Digital Media Lab - Sharif University of Technology
Why IPTV?
 IPTV will provide better quality of service than
Internet streaming video
 IPTV has the potential to offer an interactive,
customized experience
 IPTV is effective whether you require a service to
delivery or not
 Entertainment.
 Advertising or information.
 A hospitality system for hotels or hospitals.
 Regular internal bulletins.
 Up to date financial updates and market information.
18
Digital Media Lab - Sharif University of Technology
Key Features of IPTV
 Support for interactive TV: Two-way capabilities of IPTV systems allow
service providers to deliver interactive TV applications
 Time shifting: IPTV in combination with a digital video recorder allows the
time shifting of programming content
 Personalization: Allow end-users to personalize their TV viewing habits (what
& when they want to watch )
 Low bandwidth requirements: Allow service providers to only stream the
requested (not every) channel to the user => netwrok operators can conserve
bandwidth on their network
 Accessible on multiple devices: users can use their PCs and mobile devices as
well as television to access IPTV services
19
Digital Media Lab - Sharif University of Technology
How Is IPTV Done?
 Firstly we have to convert the incoming signals;

Terestrial TV,

Satellite TV,

FM and DAB Radio
into an IP format, MPEG2 and MPEG4.
 To do this we us an IPTV Encoder.
 The converted signals are then transmitted over the
LAN network with all the other data traffic, using
Multicast protocols.
 Example shows, CCTV, VoD, Satellite and
Terrestrial TV being transmitted over the same
network.
20
Digital Media Lab - Sharif University of Technology
Why Are Organizations Adopting IPTV?
 Television and video services can easily be supplied to all computers on a
network, increasing staff access to news and company information.
 The same infrastructure can be used no matter how many channels or viewing
devices are attached to the network. No special wiring or video distribution
design is required.
 Consistently high video quality is maintained regardless of the number of
people watching TV and Video services.
 Costs can be reduced by converging IPTV with existing data networks.
 Prevent major internal disturbance through the use of existing networks
Appendix D
21
Digital Media Lab - Sharif University of Technology
Overlay Network Service for IPTV
IPTV Application
IPTV Application
IPTV Application
 consists of virtual network
topologies on top of the physical
network
 responsible for forwarding and
handling of IPTV application data
Overlay Node
Overlay Network
Transport Network
IPTV Customer
22
IPTV Video Server
Digital Media Lab - Sharif University of Technology
 much more aggregate information
and computing resources for
clients or peers than from a
limited number of centralized
servers.
 operated in organized and
coherent way by the third party
service provider
or network provider to provide
IPTV services.
Overlay Network Architecture
Session
Manager
Overlay Network
Bandwidth
Manager
IPTV
Server
Network Provider 1
Overlay Node
23
Digital Media Lab - Sharif University of Technology
Network Provider 2
Functions in IPTV Overlay Network
 Control Function in IPTV Overlay Network
 Perform session control and management for IPTV overlay network.
 Establish and to maintain the network and system resources.
 Virtual link among overlay nodes creates virtual topologies to deliver IPTV information.
 Find optimal physical delivery paths for QoS and required network resource.
 Multicast Function in IPTV Overlay Network
 constructing different multicast trees depending on IPTV application parameters or application
classes.
 supports efficient routing and resource usage by overlay multicast control.
 In order to provide scalability for multicast function, hierarchical structure for overlay multicast will
be introduced in IPTV overlay networks.
 Managing session to keep track of session configuration and maintenance for IPTV
service, and provide session initiation, release and management.
24
Digital Media Lab - Sharif University of Technology
Control Functions for IPTV Overlay Multicast
 IPTV Session Manager (ISM)
ISM is involved in session configuration and maintenance
for IPTV service flows.
-
Session initialization: ISM allocates ISID (IPTV
Session ID) for new session.
-
Session release: Session can be released as needed
-
Session membership management
-
Session status monitoring
 IPTV Multicast Agent ( IMA )
- Session join: each IMA contacts with Session Manager.
- Session leave: when an IMA wants leave the session
- Session maintenance: relay request and its response will
be exchanged between the two IMAs periodically.
- Loop detection & avoidance
- Partitioning detection & recovering
- Parent switching
Appendix E
25
Digital Media Lab - Sharif University of Technology
- IPTV Session status reporting
Multimedia
Conferencing
Introduction
 Multimedia Conferencing = an interactive tool that incorporates audio, video, and
computing, and communications technologies to allow people in different locations
 To electronically collaborate face-to-face, in real time
 To share all types of information including data, documents, sound and picture.
 What is needed?
 Efficient transport:
 Enable real time transmission.
 Avoid sending the same content more than once.
 Best transport depends on available bandwidth and technology.
 Audio processing:
 How to ensure Audio/Video Quality?
 How to Mix the streams?
 Conference setup:
 Who is allowed to start a conference?
 How fast can a conference be initiated?
 Security and privacy:
 How to prevent not-wanted people from joining?
 How to secure the exchanged content?
 Floor control:
 How to maintain some talking order?
27
Digital Media Lab - Sharif University of Technology
Steps to Choosing A MultimediaConferencing System
1) Intended use for your system: how do you wish to use the equipment and whom are you going to talk to?
2) Number of sites: How many offices do you need to communicate with and what resources will each have at their
disposal?
3) Number of participants per site: How many people do you want to participate in video calls at your various
locations? Do you want the same videoconferencing set-up for every location? Or, do you want to have a more
deluxe system for your headquarters?
4) Size of your rooms: Where do you want to put the equipment? For example, is your current conference or meeting
room big enough to add a system? Does your current meeting environment offer sufficient size, lighting and
ancillary resources to accommodate an appropriate videoconferencing solution?
5) Connectivity: ISDN, BRI, PRI, T-1, Fractional T, ATM, Frame Relay, xDSL, Cable-modem? What connectivity best
suits your internal communication requirements? Will the connection be dedicated to the conferencing system?
What types of communications do you plan? Voice,video,data? (The type of communication will determine
bandwidth requirements.) Also, what connectivity will remote sites make use of?
6) What type of systems or formats will you be calling: An ISDN system typically sends and receives voice and
video data using the h.320 standard. An IP based (network) system typically communicates using the h.323
voice/video standard. You can only call between systems that subscribe to the same standard. However, gateway
and bridge devices are available that will allow you to translate calls between the common standards. (Standards
are defined by the International Telecommunications Union and are the same worldwide.)
7) Do you need data capability in addition to video & audio: Are you just looking to only see and talk to the other
people, or are you going to require the ability to do collaborative computing and share data? Do you want to share
computer files and documents on screen? Will you need to show PowerPoint presentations?
Appendix F
28
Digital Media Lab - Sharif University of Technology
How to videoconference in a Centralized Topology
 All register and send messages at a central point
 Central point forwards to others
 Tightly coupled: Some instances know all information about all participants at
all times
 Advantages




Simple to implement
Single point of failure
Appropriate for small to medium sized conferences
Simple to manage and administer:
 Allows access control and secure communication
 Allows usage monitoring
 Support floor control
 Most widely used scenario
 No need to change end systems
 Disadvantages
 High bandwidth consumption at center point
 Must receive N flows
 High processing overhead at center point
 Must decode N flows mix the flows and encode N flows
 With no mixing the central point would send Nx(N-1) flows
’06 |
How to videoconference in a Full MeshTopology
 All establish a connection to each other
 All can send directly to the others
 Each host will need to maintain N connections
 Outgoing bandwidth:
 Send N copies of each packet
 simple voice session with 64kb/s would translate to 64xN kb/s
 Incoming bandwidth:
 If silence suppression is used then only active speakers send
data
 Disadvantage
 In case of video lots of bandwidth might be consumed
 Unless only active speakers send video
 End systems need to mix the traffic –more complex end systems
 Advantage
 Security: simple! do not send data to members you do not trust
’06 |
How to videoconference in an End-Point-BasedTopology
 All establish a connection to the chosen mixer.
 Outgoing bandwidth at the mixer end point:
 Send N copies of each packet
 simple voice session with 64kb/s would translate to 64xN kb/s
 Incoming bandwidth:
 If silence suppression is used then only active speakers send
data
 Advantage
 Mostly used solution for three-way conferencing.
 Disadvantage
 In case of video lots of bandwidth might be consumed
 Unless only active speakers send video
 One of the end systems need to mix the traffic –more complex
end system.
’06 |
Benefits of Videoconferencing
 Reduces Travel Expenses: There are numerous situations where you can save a lot of money on
airfare and hotel costs, not to mention saving the loss in productivity from being out of the office.
 Allows Multi-point Meetings Across Time Zones & International Boundaries:
Videoconferencing lets you put together a meeting of various people, from different locations, for
a common discussion.

Improves Effectiveness: Visually seeing the part during a videoconference is far more effective
and meaningful than trying to describe it over the phone.
 Increases Productivity: Websites and the Internet let us quicken the speed of communication.
The use of videoconferencing will be the next driver for productivity because you will be able to
keep in closer contact with customers. This closeness will lead to new ideas on how to speed up
the development of new products and services.
 Improves Communication & Reinforce Relationships: During a videoconference you can see
the facial expressions and body language of conference participants which are both important
aspects of communication that are lost with a basic telephone call. Videoconferencing also allows
the opportunity for more of your staff to have contact with your customers.
32
Digital Media Lab - Sharif University of Technology
Appendix A
33
Digital Media Lab - Sharif University of Technology
Digital TV Standards (cont.)
Table 1 – Comparison of Digital TV standards
34
Digital Media Lab - Sharif University of Technology
DVB (Digital Video Broadcasting)
 DVB (Digital Video Broadcasting) is a set of international open
standards for digital television
 DVB standards are maintained by the DVB Project (international
industry consortium) and published by a Joint Technical Committee
(JTC) of European Telecommunications Standards Institute (ETSI),
European Committee for Electrotechnical Standardization
(CENELEC) and European Broadcasting Union (EBU)
 DVB standards are publicly available, free of charge at
http://www.etsi.org and http://www.dvb.org
 DVB standards are used in Europe; similar standards are ATSC (used
in USA/North America), ISDB (used in Japan/South America) and
DMB (used in China, Korea)
35
Digital Media Lab - Sharif University of Technology
DVB (Digital Video Broadcasting) (cont.)
 DVB standards define the physical layer and data link layer of the distribution
system
 DVB standards are based on MPEG-2 and MPEG-4 standards and all data is
transmitted in MPEG Transport Streams
 Most important DVB standards are:
 for satellite TV: DVB-S, DVB-S2
 for terrestrial (aerial) TV: DVB-T, DVB-T2
 for cable TV: DVB-C, DVB-C2
 for handheld devices TV: DVB-H, DVB-SH
 DVB has a conditional access system (DVB-CA) through Common Scrambling
Algorithm (DVB-CSA) and a physical Common Interface (DVB-CI)
 DVB-S and DVB-C were ratified in 1994 and DVB-T in 1997
36
Digital Media Lab - Sharif University of Technology
DVB-J
 Special Java platform for digital
television
 JVM is part of OS
 A few interfaces




37
DAVIC
 Digital Audio Visual Council
 Payment interfaces
 Infrastructure interfaces
 Tuning interfaces
DVB
 Digital Video Broadcasting
 Extensions and limitations to Javainterfaces
 Data access interfaces
 I/O-device interfaces
 Security interfaces
Java
 Basic interfaces: lang, util, beans...
 Graphical libraries: AWT, JMF
 Service interfaces: JavaTV
HAVi
 Home Audio Video Interoperability
 Display and user interface libraries
Digital Media Lab - Sharif University of Technology
DVB-HTML
 Digital Video Broadcasting – HyperText Markup Language
 HTML-like environment for television
 Technologies
 xml, xhtml, css, dom, ECMAScript
 Pages or ”screens” are received from media carusel
 Same way of thinking as in normal teletext service.
 Modern version of Teletext services
 DVB-HTML services are very often called as supertext-tv services.
 It will replace the normal teletext services.
 New services possible but already launched applications are the same as in normal teletext but with
pictures
 Interactive services
 DVB-HTML includes forms and links as a way to browse within service
 Forms makes it possible to build up somehow interactive content.
 Need to remember that actual content for pages is received from media carusel.
 Few example services





News
Extra information about tv-series or events
Traffic jam information, bus timetables
Subject specific portals
Payment services
 Order new services or products via television. (requires feedback channel)
38
Digital Media Lab - Sharif University of Technology
Example of DVB-HTML page









<?xml version="1.0" encoding="ISO-8859-1"?><!DOCTYPE html SYSTEM "supertext.dtd">
<html>
<head>
<title>SM-Liiga</title>
<link rel="stylesheet" href="styles1Column.css"/>
</head>
<body>
<div class="title">
<span style="width: 200;">Tilastot
</span>













39
</div>
<div class="main">
<br><span class="lihavointi"></span><br><br>
<table>
<tr>
<td>SARJATAULUKKO</td>
<td ></td>
</tr>
<tr>
<td bgcolor="#cccccc"></td>
</tr>
........
Digital Media Lab - Sharif University of Technology
Multimedia Home Platform (MHP)
 MHP is
 An open DVB standard which defines a whole set of technologies to implement
 A set of Java APIs
 A set of HTML document type definitions
 A set of compatibility tests
 Digital interactive multimedia services in the home
 Includes home terminal (e.g., set-top box, TV set, or PC) and its peripherals and the in-home digital
network
 Covers three application areas (i.e., enhanced broadcasting, interactive broadcasting, and Internet
access)
 MHP goals
 primary goal of the MHP is to enable the birth of horizontal markets for digital television and
multimedia services where there is open competition between content providers, network operators or
platform manufacturers at each level in the delivery chain.
 Another goal is to exploit the potential for convergence between broadcasting, the Internet and
consumer electronics.
40
Digital Media Lab - Sharif University of Technology
Multimedia Home Platform (MHP) (cont.)
 Three main standards are related to MHP
 MHP 1.0.x (1.0.0 – 1.0.3)
 The original MHP specification plus updates
 The most commonly deployed version of MHP
 MHP 1.1.x
 Adds elements that were not finished in time for MHP 1.0.0
 HTML support, stored applications, Internet client APIs, smart card APIs
 Still a work in progress
 Version 1.1.2 coming in April 2005
 Globally Executable MHP (GEM)
 A subset of MHP 1.0.2
 Designed to form the basis of other DTV middleware standards
 Currently used by OCAP, ACAP and ARIB B23
 Also PVR for MHP specification (to be published April 2005)
 Adds support for PVR functionality to MHP receivers
 Compatible with OCAP PVR extensions
41
Digital Media Lab - Sharif University of Technology
MHP profiles
+ Java Internet client APIs
+ Web browser & email client
+ DVB-HTML (optional)
Internet Access
profile
+ Java APIs for return channel
+ Protocols for return channel
Interactive
Broadcast
profile
Enhanced
Broadcast
profile
HTTP 1.0, DNS, HTTPS
mandatory
HTTP 1.1, DSMCC-UU optional
+Java VM
+DVB Java APIs
+Basic media formats
(MPEG, GIF, JPEG, PNG, etc.)
+ Application storage
+ Smart card APIs
+Broadcast transport protocols
MHP 1.0.x
42
+ DVB-HTML (optional)
+ App download over HTTP
+ Inner applications
Digital Media Lab - Sharif University of Technology
MHP 1.1.x
Multimedia Home Platform (MHP) (cont.)
 MHP architectural layers
 Resources: MPEG processing, I/O devices, CPU, memory and a graphics system
 System software: The system software uses the available resources in order to provide an abstract view of
the platform to the applications.
 Applications : They are controlled by the application manager
 API Interface: Defined by MHP as abstraction layer between different provider's applications and the
specific hardware and software on the terminal
 Digital TV applications use APIs to access the actual resources of the receiver, including: databases,
streamed media decoders, static content decoders and communications.
Figure 1 – Basic MHP Architecture
43
Digital Media Lab - Sharif University of Technology
MHP Applications
 Information services
 super teletext, etc.
 Show-related interactivity
 online quiz show, online
voting, etc.
Game
 Games
 T-commerce and banking
 Internet access
Banking
super teletext
44
Digital Media Lab - Sharif University of Technology
Remote controller, An MHP Device
 MHP defines





Arrow keys
OK
TXT
Numbers 0-9
Color keys (in this order): red, green, yellow, blue
 There are also other keys, that are not required
 NorDig II suggests
 Power ON / OFF
 Programme UP / DOWN
 Volume UP / DOWN
 TV
 Back
45
Digital Media Lab - Sharif University of Technology
MHP Graphics
 32-bit colors
 MHP minimum palette (140+48 colors)
 Alpha channel
 0%, 30%, 100% required by MHP
 If other values not supported, values are
rounded to these.
 3 layers
 background
 video
 graphics
 Java drawing primitives
 Image formats
 JPEG, GIF, PNG, MPEG I-Frame
 Scaled video
46
Digital Media Lab - Sharif University of Technology
MHP Layers
 Background
 Only one still image
Background
 MPEG I-Frame bitmap
 Always full-screen
 Opacity cannot be set
 Video
 MPEG-video from TV-stream
Video
 Video is scalable
 Full screen, 1/4, 1/16
 Other if device supports
 Some devices supports multiple simultaneous video
streams, but this is not required by MHP-standard
 Graphics
 Graphic layer
Graphics
 Application graphics
47
Digital Media Lab - Sharif University of Technology
Appendix B
48
Digital Media Lab - Sharif University of Technology
Challenges of VOIP (cont.)
49
Digital Media Lab - Sharif University of Technology
Current VOIP Implementations
50
Digital Media Lab - Sharif University of Technology
Enterprise Applications of VoIP
 Leverage spare data-network capacity, minimize phone bills,
create platform for multimedia conferencing
 H.323 and SIP both being deployed, softswitches and IP-PBX
options emerging, unclear which will prevail
 Examples: Telcordia/SAIC (H.323), Telia (SIP)
 Carrier-managed VPN networks last year from AT&T (H.323)
and Worldcom (SIP)
 VoIP adoption slower than expected, partly due to plunging PSTN
long-distance prices, QoS concerns
51
Digital Media Lab - Sharif University of Technology
VOIP Advanced Services
 VoIP: natural platform for evolution to advanced services
 Supports intelligent terminals and rich signaling
 Separates calls from connections
 Multimedia capabilities already in the protocols (SIP/H.323)
 Removes bottleneck by separating call control from switching
 Thus far, focus is almost entirely on voice
 For many players (but not all), voice is the killer app
 Solve the simpler problem first
 This simplifies many network control issues, because of predictability of
voice bandwidth, traffic patterns
 But current solutions are likely to require significant extensions to
accommodate more flexible advanced services
52
Digital Media Lab - Sharif University of Technology
What’s Different About Advanced Services?
 Flexibility in media streams, participants, “ownership”; service not pre-defined
at call setup
 Multiple media per call, differing (and very wide range of) bandwidths
 Dynamic re-configurability during call
 Potential for multicast conferencing, streaming
 Implications
 Call admission control becomes more complex
 Much less aggregation, localization of flows than with NGN voice
 Usage, traffic patterns may be highly variable and hard to predict
 New approaches to traffic engineering, resource allocation and network control
will be needed to address even a modest penetration of these new services
53
Digital Media Lab - Sharif University of Technology
Appendix C
54
Digital Media Lab - Sharif University of Technology
IP Telephony
 Internet telephony uses the Internet protocol to send audio, video an data between two
or more users in the real time.
 IP telephony is the integration and convergence of voice and data networks, services,
and applications.
 The main motivation of development of IP Telephony is the cost saving & integrating
new services.
 IP Telephony Standards
 H.323 standard
 Session initiation protocol (SIP)
 Media gateway to media controller protocol (MGCP)
 IP Telephony types
 PC to PC
 Phone-to-phone over IP
 PC-to-Phone
 Phone-to-PC
55
Digital Media Lab - Sharif University of Technology
IP Telephony: PC-to-PC
56
Digital Media Lab - Sharif University of Technology
IP Telephony: Phone-to-Phone Using Gateways
57
Digital Media Lab - Sharif University of Technology
IP Telephony: Phone-to-Phone Using Adapter
Gateways
58
Digital Media Lab - Sharif University of Technology
IP Telephony: PC-to-Phone
59
Digital Media Lab - Sharif University of Technology
Appendix D
60
Digital Media Lab - Sharif University of Technology
Components of an IPTV System
 A National head-end - Origination point of network Broadcasts for transmission over the IP
network.
 Core networks - Usually an IP/MPLS network transporting traffic to the access network
 Access networks - Distributes the IPTV streams to the Digital Subscriber Line Access
Multiplexer (DSLAMs)
 Regional head-end – Origination point for local content
 Customer premises - Where the IPTV stream is terminated and viewed using a Set Top Box
or Computer.
Figure 2 – A
typical IPTV
system
61
Digital Media Lab - Sharif University of Technology
Components of an IPTV System (cont.)
 Hardware Blocks
 BF5333 processor: Design for computational demands, power constraints of
embedded audio and video applications
Figure 3 - An IPTV system block diagram
62
Digital Media Lab - Sharif University of Technology
Components of an IPTV System (cont.)
 Video Encoder ADV7171: converts digital CCIR-601 4:2:2 8- or 16-bit component video
data to an analogue baseband television signal compatible with worldwide standards
 Audio Codec AD1836: A codec providing three stereo DACs and two stereo ADCs
 Ethernet Interface SMSC LAN91C111 Chip: facilitate the implementation of a third
generation of Fast Ethernet connectivity solutions for embedded applications
 Set-Top Box (STB): A dedicated computing device that serves as an interface
between a TV set and a broadband network
 Main job = receive incoming IPTV signal & convert to a video signal that can be displayed in TV
 Allow viewers to select their video programming
 Supports Web browsing, email & viewing email attachments, advanced multimedia codecs,
instant messaging, and real-time VOIP.
63
Digital Media Lab - Sharif University of Technology
Components of an IPTV System (cont.)
 Software Blocks:
 uClinux OS: this OS is loaded to memory and divided into kernel space (contain
system functions) and user space (contain application program)
 Video Driver: Responsible for video applications
 Audio Driver: Responsible for audio applications
 Media Player: uses FFmpeg which is a complete solution to record, convert, &
stream audio and video
 Streaming: STB creates connection to server for streaming the media
 User Interface: An interface between user & IPTV STB to make STB interactive
with user
64
Digital Media Lab - Sharif University of Technology
IPTV Issues
 Encoding and Compression – The quality of a transmission can be affected from the source
depending on the encoding technique and level of compression. Generally speaking increased
compression leads to a poorer video quality but a smaller data stream. There is a tradeoff
between bandwidth and compression level.
 Jitter in IPTV transmission is defined as a short-term variation in the packet arrival time.
Jitter is typically caused by network or server congestion. To help combat jitter, STB’s use
buffers to smooth out the arrival times of the data packets. I the buffer overflows or
underflows, at the STB, there is often a degradation of the video output.

Limited Bandwidth – Bandwidth availability is often an issue that affects the access
network or the customers home network. When traffic utilizes the entire bandwidth, packets
are dropped, leading to video quality degradation.
 Packet Loss - Loss of IP packets may occur for multiple reasons:





65
bandwidth limitations
network congestion
failed links
transmission errors
Packet loss usually presents a bursty behavior, commonly related to periods of network
congestion.
Digital Media Lab - Sharif University of Technology
Appendix E
66
Digital Media Lab - Sharif University of Technology
Additional capabilities of IPTV Overlay Network
 Multicast Resource Management
 Provide control function to multicast congestion problem
 Multicast resource management
 Re-negotiation function for additional resource requirements
 Multiple data routing function for service/user requirements
 Quickly detection of network problems for IPTV services
 Provision of Intelligence for IPTV Service Features
 Provision of dynamic creation and control function of IPTV Service Communities
 QoS+Security+User’s Preference
 Keywords/Program searching for IPTV Services
67
Digital Media Lab - Sharif University of Technology
Overlay IPTV Multicast Control
 Group membership management
 Group Membership Control
 Group Partitioning: Global group partitioning, Server group partitioning
 Admission control
 support QoS for IPTV services in overlay multicast network
 resource control function for IPTV overlay network
 Security for IPTV overlay multicast
 Confidentiality and Integrity, Authenticity, and Availability.
 Classified with some properties for architectures and algorithms for building secure
and scalable information dissemination services on IPTV overlay networks.
68
Digital Media Lab - Sharif University of Technology
Appendix F
69
Digital Media Lab - Sharif University of Technology
Multimedia Conferencing Applications
 Business
 Reduce travel costs, improve use of executive time, speed up decision-making, keep
meetings brief and more focused than face-to-face meetings, enable top management to
quickly and effectively communicate with employees sitting in multiple locations, provides
an effective way of delivering cost-efficient training to individuals without the requirement to
consistently travel to central locations.
 Distance learning
 Teachers and students are able to see each other, share documents and discuss topics
together in a situation similar to a traditional classroom setting while they are in various
countries.
 Saving travel time and expenses, increasing an instructor’s audience, maintaining the
ability for interaction between teachers and students
 Telemedicine
 When a person needs medical advice but is unable to visit their personal physician or a
specialist. Videoconferencing enables patients to get the necessary information and expert
guidance they need quickly and easily.
 Telecommuting/Home office
 Users can save resources by meeting with clients and/or colleagues via videoconference.
This reduces travel expenses, while maintaining face-to-face contact. For a minimal cost, it
is possible to set-up a fully functional videoconferencing system that works in a
professional and reliable way from your home office.
70
Digital Media Lab - Sharif University of Technology
Components of Multimedia Conferencing
 Videoconferencing Codec Unit (End Points) = “BRAIN and HEART” of
the Videoconferencing (multimedia conferencing) System
 It is also known as the Coder-Decoder.
 Function
1.
It takes the video and audio from the camera and microphone
2.
Compresses it down
3.
Transmits it over a network/digital phone line
4.
Expands (or Decompresses) the incoming video and audio signal so that it
can be viewed on a display

Camera: The camera types range from a small desktop camera that sits on
top of a computer monitor in a desktop system to a high-quality camera that
has remote control pan, tilt and zoom (PTZ) features in a room-sized
system.
 Microphone : small microphones that attach to the Personal Computer in a
desktop conferencing unit, or a microphone designed to work best with a
small group of people in a room-sized system.
’06 |
Components of Multimedia Conferencing(cont.)
 Video Monitor, XGA Monitor, Plasma Display,
LCD/DLP Projector
 These display devices are options that can be used to show
the images received from the videoconferencing codec.
 Videoconferencing systems can use multiple displaying
options. Desktop systems show the video in a small window
on the computer monitor. Room-sized systems usually have
one or two large video monitors and can display the local
audience, as well as the remote audience.
 Network Connection
 This is the connection that carries data between video
systems communicating with one another. The size of the
connection and the ability to access it in a consistent manner,
determines both video performance and quality of service.
The connection can range from an ISDN phone line to a
dedicated PRI/T-1 connection or access to a local area
network.
72
Digital Media Lab - Sharif University of Technology
Types of Multimedia Conferencing Systems
 Desktop Multimedia Conferencing Systems:
This technology
can deliver full-motion Multimedia Conferencing from your PC.
 Desktop systems have been engineered to accommodate the
industry's requirements for standards-based videoconferencing.
 There are systems available that deliver high quality at a low
cost.
 These systems provide H.323 voice and video, as well as
applications sharing.
 They offer easy installation and many have no add-in boards to
install or bulky hardware to place on your desk.
 Set-top Multimedia Conferencing Systems:
Set-tops are
complete Multimedia Conferencing systems designed to sit on a monitor.
 Useful in small boardrooms and other small group scenarios.
 Are often maintained on a cart, making it possible to roll them
around for use in different rooms.
 Have excellent video quality and work well with auxiliary
equipment, such as document cameras, to enhance
videoconference presentations.
73
Digital Media Lab - Sharif University of Technology
Types of Multimedia Conferencing Systems (cont.)
 Integrated Multimedia Conferencing Systems:
Integrated systems are group conferencing systems most often used in
conference rooms or classrooms with multiple participants.
 This type of system usually consists of a centralized location
for wiring and processors to be routed. The main camera,
displays and peripheral video sources are usually mounted in
the main conferencing area.
 These customized configurations are normally equipped with
multiple features and also allow for the videoconferencing room
to be used for other various functions as well.
 Most integrated systems available today are capable of
connecting both H.320 (ISDN lines) and H.323 (IP/LAN).
74
Digital Media Lab - Sharif University of Technology