Seminar Report IPTV

TABLE OF CONTENTS:

S. NO. TOPICS PAGE NO.

1 Introduction 2

>About IPTV 3

2 Working 3

3 Technology 6

4 Protocols 7

>H.246 AVC 7

>IGMP 8

5 Main Building Blocks of IPTV 10

>Stream Server 10

>Video Server 10

>Level III Device 11

>DSLAM 12

>CPE(Customer Premises Equipment) 13

>STB 14

6 Advantages of IPTV 15

7 Disadvantages of IPTV 16

6 Conclusion 17

7 Bibliography 18

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Introduction

Internet Protocol Television (IPTV) is broadcast-quality television and/or video signals that are delivered to subscribers or viewers using a broadband connection over Internet Protocol (IP). While IP stands for Internet Protocol, it does not actually mean the television content is streaming over the Internet. IP is simply the same method, protocol, or technology that enables you to access the Internet and IP-delivered television content is utilizing the same technology for delivery.

IPTV operates on a different premise than traditional satellite or cable television in that only selected programming and on-demand content are delivered to the consumer. With Satellite and cable, all channels are being pushed all the time to the consumer's home rather than a per-selection basis. IPTV's ability to provide two-way communication (you request a program from the TV guide and the program is delivered to you) offers true interactivity for the customer with the environment. HDTV, movies, past TV shows, and all other content can be distributed on demand and service providers can tailor the requested content and advertising based on customer preference.

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IPTV also offers such potential as on-demand video gaming and because it is using your broadband connection, it can interact with other Internet services such as Voice over IP (VoIP). Consumers may have caller ID displayed on their television. The potential is truly unlimited.

History

In 1994,ABC's World News Now was the first television show to be broadcast over the Internet, using the CU-SeeMe videoconferencing software. Internet radio company AudioNet started the first continuous live webcasts with content from WFAA-TV in January, 1998 and KCTU-LP on January 10, 1998.[1] [2] [3] In the past, this technology has been restricted by low broadband penetration. In the coming years, however, residential IPTV is expected to grow at a brisk pace as broadband is now available to more than 100 million households worldwide. Many of the world's major telecommunications providers are exploring IPTV as a new revenue opportunity from their existing markets and as a defensive measure against encroachment from more conventional Cable Television services. In the mean time, there are thousands of IPTV installations within schools, corporations, and other institutions that do not require the use of wide area connectivity.

Working

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First things first: the venerable set-top box, on its way out in the cable world, will make a resurgence in IPTV systems. The box will connect to the home DSL line and is responsible for reassembling the packets into a coherent video stream and then decoding the contents. Your computer could do the same job, but most people still don't have an always-on PC sitting beside the TV, so the box will make a comeback. Where will the box pull its picture from? To answer that question, let's start at the source.

Most video enters the system at the telco's national headend, where network feeds are pulled from satellites and encoded if necessary (often in MPEG-2, though H.264 and Windows Media are also possibilities). The video stream is broken up into IP packets and dumped into the telco's core network, which is a massive IP network that handles all sorts of other traffic (data, voice, etc.) in addition to the video. Here the advantages of owning the entire network from stem to stern (as the telcos do) really come into play, since quality of service (QoS) tools can prioritize the video traffic to prevent delay or fragmentation of the signal. Without control of the network, this would be dicey, since QoS requests are not often recognized between operators. With end-to-end control, the telcos can guarantee enough bandwidth for their signal at all times, which is key to providing the "just works" reliability consumers have come to expect from their television sets.

The video streams are received by a local office, which has the job of getting them out to the folks on the couch. This office is the place that local content (such as TV stations, advertising, and video on demand) is added to the mix, but it's also the spot where the IPTV middleware is housed. This software stack handles user authentication, channel change requests, billing, VoD requests, etc.—basically, all of the boring but necessary infrastructure.

All the channels in the lineup are multicast from the national headend to local offices at the same time, but at the local office, a bottleneck becomes apparent. That bottleneck is the local DSL loop, which has nowhere near the capacity to stream all of the

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channels at once. Cable systems can do this, since their bandwidth can be in the neighborhood of 4.5Gbps, but even the newest ADSL2+ technology tops out at around 25Mbps (and this speed drops quickly as distance from the DSLAM [DSL Access Multiplier] grows).

So how do you send hundreds of channels out to an IPTV subscriber with a DSL line? Simple: you only send a few at a time. When a user changes the channel on their set-top box, the box does not "tune" a channel like a cable system. (There is in fact no such thing as "tuning" anymore—the box is simply an IP receiver.) What happens instead is that the box switches channels by using the IP Group Membership Protocol (IGMP) v2 to join a new multicast group. When the local office receives this request, it checks to make sure that the user is authorized to view the new channel, then directs the routers in the local office to add that particular user to the channel's distribution list. In this way, only signals that are currently being watched are actually being sent from the local office to the DSLAM and on to the user.

No matter how well-designed a network may be or how rigorous its QoS controls are, there is always the possibility of errors creeping into the video stream. For unicast streams, this is less of an issue; the set-top box can simply request that the server resend lost or corrupted packets. With multicast streams, it is much more important to ensure that the network is well-engineered from beginning to end, as the user's set-top box only subscribes to the stream—it can make no requests for additional information. To overcome this problem, multicast streams incorporate a variety of error correction measures such as forward error correction (FEC), in which redundant packets are transmitted as part of the stream. Again, this is a case where owning the entire network is important since it allows a company to do everything in its power to guarantee the safe delivery of streams from one end of the network to the other without relying on third parties or the public Internet.

Though multicast technology provides the answer to the problem of pumping the same content out to millions of subscribers at the same time, it does not help with features such as video on demand, which require a unique stream to the user's home. To support VoD and other services, the local office can also generate a unicast stream that targets a particular home and draws from the content on the local VoD server. This stream is typically controlled by the Real Time Streaming Protocol (RTSP), which enables DVD-style control over a multimedia stream and allows users to play, pause, and stop the program they are watching.

The actual number of simultaneous video streams sent from the local office to the consumer varies by network, but is rarely more than four. The reason is bandwidth. A Windows Media-encoded stream, for instance, takes up 1.0 to 1.5Mbps for SDTV, which is no problem; ten channels could be sent at once with bandwidth left over for voice and data. But when HDTV enters the picture, it's a different story, and the 20-25Mbps capacity of the line gets eaten up fast. At 1080i, HDTV bit rates using Windows Media are in the 7 to 8 Mbps range (rates for H.264 are similar). A quick calculation tells you that a couple of channels are all that can be supported.

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The bandwidth situation is even worse when you consider MPEG-2, which has lower compression ratios. MPEG-2 streams will require almost twice the space (3.5 Mbps for SDTV, 18-20 Mbps for HDTV), and the increased compression found in the newer codecs is one reason that AT&T will not use MPEG-2 in the rollout of its IPTV service dubbed "U-verse."

Simultaneous delivery of channels is necessary to keep IPTV competitive with cable. Obviously, multiple streams are needed to support picture-in-picture, but they're also needed by DVRs, which can record one show while a user is watching another. For IPTV to become a viable whole-house solution, it will also need to support enough simultaneous channels to allow televisions in different rooms to display different content, and juggling resulting bandwidth issues is one of the trickiest parts of implementing an IPTV network that will be attractive to consumers.

IPTV technology

As often occurs in markets based on rapidly evolving technologies, IPTV may be able to leapfrog the standard cable offering in certain areas. However, because more bandwidth is inherently available in data streams sent over coax than those that use twisted-pair wiring, the IPTV industry faces significant challenges.

Bandwidth needs

The majority of IPTV transmission today uses MPEG2 encoding, which is a "lossy" compression algorithm that encodes standard video (SDTV) into roughly 4-Mbit/sec streams and HDTV into roughly 20-Mbit/sec streams. The size of HDTV streams is problematic for wireline providers, as only the enhanced DSL technologies can transfer a stream exceeding 10 Mbits/sec, and they suffer from limited reach and/or high cost. This is pressing the IPTV providers to change their encoding to MPEG4, which roughly doubles the compression ratio of MPEG2.

Using the combination of enhanced DSL and MPEG4 technologies, wireline carriers can transmit a single HDTV stream with some bandwidth available for voice and data. However, subscribers demand more than one HDTV channel, forcing wireline carriers to press forward with aggressive, optics-based transmission schemes. The most successful appears to be PON, an Ethernet-oriented scheme that provides roughly 100 Mbits/sec per subscriber and uses passive optical splitters. PON-based systems can deliver several HDTV streams, broadband data, and several VoIP streams to each

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subscriber. Wireline carriers can only be truly competitive with cable when these networks are in place.

Whatever the technology used, the increase in bandwidth of IP traffic is tremendous. Just a few households receiving HDTV channels have the same bandwidth demand as a small city of DSL users--which profoundly affects existing equipment.

Loss sensitivity

MPEG4, typically encoded to comply with H.264, uses an extremely complex distributed Discrete Cosine Transform (DCT) to remove high-frequency components. It also takes advantage of the limited color space that the human eye can perceive to further remove information content. In addition, it uses motion prediction to estimate what the forward frame will look like and only sends the differences between the actual frame and the predicted frame forward. Since the only information that is sent is the difference between the predicted frame and the actual frame, required bandwidth is reduced.

All of these are combined in a stream of key frames (I-frames) containing complete images, each followed by one or more P-frames, each of which contains the predicted frame data. Interspersed between the I and P frames are a short sequence of B frames, which contain the differences between the I and P frames at different time points. Because the complete image is refreshed at the I-frame rate, which typically occurs at two frames per second, error magnification can be significant. Errors in the P and B frames will persist for up to half a second, and I frame errors can cause errors for up to a second.

Almost all of the video sent assumes that the previous frames were correct, which is very different from SDTV in which the screen is refreshed more than 12 times per second. In order to maintain perceived quality consistent with that of SDTV, IPTV must be designed so that frames are not dropped.

PROTOCOLS

Protocol encoding for IPTV

The roundtrip delay of today's networks does not allow time for the retransmission of errored or dropped frames. The video stream typically is encapsulated using real-time transport protocol (RTP), encoded as described in the IETF standard, RFC 2250 or "RTP Payload Format for MPEG1/MPEG2 Video." This encapsulation places key information, such as temporal references and frame-type information in the

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header, where it can be used to recover from errors and frame losses even before the video decoding is performed. The RTP-encoded frames are transmitted using user datagram protocol (UDP) encapsulation. UDP is extremely lightweight and does not provide any correction for errors or losses. This differs from Internet traffic, which uses transmission control protocol (TCP)/IP. The UDP/IP frames are transferred over the wireline providers' networks using Ethernet equipment.

By using the same protocol stack as the Internet, wireline providers reap the benefit of lower-cost datacom equipment. This benefit is increased through the use of multicast IP protocols. By encoding a video stream as a multicast Ethernet frame, many subscribers can share the same stream. The selection of which streams to send to which subscribers now can be made using multicast control protocols, such as Internet group management protocol (IGMP) at the edges and protocol independent multicast (PIM) at the core. This has the tremendous benefit of allowing the demands of the users to dictate where the video streams flow.

IPTV covers both live TV (multicasting) as well as stored video (Video on Demand VOD). Video content is typically compressed using either a MPEG-2 or a MPEG-4 codec and then sent in an MPEG2 Transport Stream delivered via IP Multicast in case of live TV or via IP Unicast in case of Video on Demand.

In standards-based IPTV systems, the primary underlying protocols used for:

# Live TV is IGMP version .

# VOD is RTSP.

PROTOCOLS

H.264/MPEG-4 AVC Coding (advanced Video Coding)

Features:H.264/MPEG-4 AVC cuts the bandwidth required to deliver full-screen DVD-

quality digital video to consumers up to 700 kbps that is suitable within the capabilities of a 1.5 Mbps DSL loop. H.264 opens the door to new opportunities and reduces operating and deployment costs when compared to MPEG-2. There are several reasons:

H.264/MPEG-4 AVC addresses the needs for greater compression, leading to lower data rates, while maintaining broadcast quality for video-on-demand (VOD)

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and high-definition television (HDTV) needs.

This advance has followed the evolution of video compression technique toward higher quality and lower bandwidth.

More content can be transmitted on longer loops to more customers. Where MPEG-2 could only reach customers in a 9,000 sq. ft service area per CO, H.264/AVC video streams can reach customers in a 16,000 sq. ft service area per CO.

In normal digital television MPEG-2, HD video requires around 30Mbit/s of bandwidth, but newer compression technologies (such as MPEG-4 H.264) require only 6-9Mbit/s, which is very achievable over existing DSL infrastructure.

H.264 compresses video more efficiently, cutting transmission costs over satellite or terrestrial links.

H.264/MPEG-4 AVC enables reaching greater distances over DSL with more content.

H.264/MPEG-4 AVC benefits bandwidth demand, storage requirement, and download times H.264/MPEG-4 AVC addresses the needs for greater compression, leading to lower data rates, while maintaining broadcast quality for video-on-demand (VOD) and high-definition television needs.

H.264 meets the needs of both broadcast and the Internet by cutting the MPEG-2 bit rates in about half for digital video transmission-without a loss in video quality.

This advance has followed the evolution of video compression science toward higher quality and lower bandwidth, and it opens new doors for service providers operating over the local copper loop infrastructure. Using H.264/MPEG-4 AVC and new H.264-enabling technology platforms for encoding, transport, and decoding, Telco’s and ISPs can boost their average revenue per user (ARPU) with exciting and compelling new video-on-demand, HDTV distribution, and interactive TV services. The age of IPTV over DSL has arrived. IGMP

The Internet Group Management Protocol (IGMP) is the Internet protocol, part of the Network Layer. IGMP is formally described in the Internet Engineering Task Force (IETF) Request for Comments (RFC) 2236.

IGMP provides a way for an Internet computer to report its multicast group

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membership to adjacent routers. Multicasting allows one computer on the Internet to send content to multiple other computers that have identified themselves as interested in receiving the originating computer's content.

Multicasting applications: updating the address books of mobile computer users in the field sending out company newsletters to a distribution list "broadcasting" high-bandwidth programs of streaming video to an audience

IPTV Main Building Blocks

Streaming Server

Streaming server resides at the head- end. It can encode and stream live streams in real-time and pre-encoded streams that are stored on the video server.

Streaming server transmits the streams to the switch or router which transfers them over the backbone to the central/remote offices and from there to the end user location.

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Video Server

Video servers fulfill several purposes .For store and forward transmissions video servers store digitally encoded content and stream it through level III devices via operators’ networking infrastructure.

Video servers receive newly encoded digital content that is uploaded from the streaming server.

Video servers also enable time shifted TV applications. Viewers at home can then watch any program at a time convenient to them.

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Level III Device

A switch or router that supports Multicast transmission. The router or switch resides at the head-end, interfacing with the network.

Another router or switch receives data at the central office and transmits either to DSLAMS located there, or into end-user network.

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DSLAM

A DSLAM (Digital Subscriber Line Access Multiplexer) is a network device, usually at a telephone company central office, that receives signals from multiple customer Digital Subscriber Line (DSL) connections and puts the signals on a high-speed backbone line using multiplexing techniques.

Depending on the product, DSLAM multiplexers connect DSL lines with some combination of asynchronous transfer mode (ATM), frame relay, or Internet Protocol networks.

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DSLAM enables a phone company to offer business or homes users the fastest phone line technology (DSL) with the fastest backbone network technology (ATM). The DSLAM (Digital Subscriber Line Access Multiplexer) resides at the central office, connecting xDSL subscribers to the backbone and subsequently to the head-end.

When distributing TV over IP, the DSLAM should support multicast transmission. If it doesn’t, the switch or router at the central office has to replicate each channel for each request. This can cause congestion at the DSLAM input level. If the DSLAM supports multicast, it receives one stream for each channel and replicates the stream for each end point.

CPE (Customer Premises Equipment)

The equipment located at the end-point that receives the TV/IP stream. Usually the term CPE refers to the DSL modem.

The DSL modem receives the stream from the DSLAM or Level III device and transfers it directly to the PC for display on the desktop or to the IP STB.

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Set-top Box (STB)

Gateway between TV set/PC-TV and NT (PSTN line, satellite or cable) Signal processing – receiving, decoding/decompressingSTB also accepts commands from the user and transmits these commands back to the network, often through a back channel.

Functions - TV signal receiver, modem, game console, Web browser, e-mail capabilities, video-conferencing, cable telephony

Components - Electronic Program Guide (EPG), CD ROM, DVD player etc. Many STBs are able to communicate in real time with devices such as

camcorders, DVDs, CD players and music keyboards Hardware Data network interface Decoder Buffer Synchronization hardware

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Types of STB (1) Broadcast TV Set-top Boxes - (Thin Boxes)More elementary level set-top box with no return channel (back-end). Some memory, interface ports and some processing power. (2) Enhanced TV Set-top Boxes - (Smart TV set-top box, Thick Boxes) These have a return channel, usually through a phone line. Video on Demand, Near Video on Demand, e-commerce, Internet browsing, e-mail communications and chat. (3) Advanced Set-top Boxes - (Advanced digital Set-top boxes, Smart TV Set-top box, Thick Boxes)Like a PC -processors, memory and optional large hard-drives. (4) All-in-one Set-top Boxes - (Integrated set top box, Super Box)A fully integrated set-top box. Features could include everything from high-speed Internet access to digital video recording to games and e-mail capacity.

Advantages of IPTV

Advantages of IPTV include two-way capability lacked by traditional TV distribution technologies

, as well as point-to-point distribution allowing each viewer to view individual broadcasts. This enables stream control (pause, wind/rewind etc.) and a free selection of programming much like its narrowband cousin, the web.

IPTV covers both live TV (multicasting) as well as stored video (Video on Demand VOD). The playback of IPTV requires either a personal computer

or a "set-top box" connected to a TV. Video content is typically MPEG2TS delivered via IP Multicast, a method in which information can be sent to multiple computers at the same time, with the newly released H.264 format thought to replace the older MPEG-2.

In standards-based IPTV systems, the primary underlying protocols used for IPTV are IGMP version 2 for channel change signaling for live streaming

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Disadvantages of IPTV

IPTV is sensitive to packet loss and delays if the streamed data is unreliable. IPTV has strict minimum speed requirements in order to facilitate the right number of frames per second to deliver moving pictures. This means that the limited connection speed/bandwidth available for a large IPTV customer base can reduce the service quality delivered.

Although a few countries have very high speed broadband-enabled populations, such as South Korea with 6 million homes benefiting from a minimum connection speed of 100Mbit/s, in other countries (such as the UK) legacy networks struggle to provide 3-5 Mbit/s and so simultaneous provision to the home of TV channels, VOIP and Internet access may not be viable. The last mile delivery for IPTV usually has a bandwidth restriction that only allows a small number of simultaneous TV channel streams – typically from one to three – to be delivered.

The same problem has also proved troublesome when attempting to stream IPTV across wireless links within the home. Improvements in wireless technology are now starting to provide equipment to solve the problem.

Due to the limitations of wireless, most IPTV service providers today use wired home networking technologies instead of wireless technologies like 802.11. Service Providers such as AT&T (which makes extensive use of wireline home networking as part of its U-Verse IPTV service) have expressed support for the work done in this direction by ITU-T, which has adopted Recommendation G.hn (also known as G.9960), which is a next generation home networking standard that specifies a common PHY/MAC that can operate over any home wiring (power lines, phone lines or coaxial cables)

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CONCLUSION

The basic aim behind seminar is to gain in depth knowledge about the topic on which seminar is being presented. It imparts technical knowledge to the students who learn from their presentation. They gain information on the latest technologies by seminar of other students.

IPTV enables broadband service providers provide the “triple play” to users, open opportunity to takeover TV market and earn money. On the other hand viewer will get advanced and on demand entertainment.

An IPTV offers you a advanced multi channel high definition TV (HDTV) as well as on demand entertainment. IPTV technology promises to give better and more contents available, Because of two way connection between viewer and service provider will know the views personal preferences and entertain them accordingly. IPTV Middleware providers gives focus on making more content available to viewers, easy to use and portable solutions.

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BIBLIOGRAPHY

Websites:

www.google.com www.iptv.com

www.iptvparts.com

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