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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