Dr. Hossein Eslambolchi
By 2015, 91 percent of Internet traffic will be video, as opposed to voice and gaming. The advent of wireless LTE broadband will enable this massive amount of video traffic for both consumers and businesses.
• IP video is an all-encompassing term for digital video transmission that uses IP as the endpoint addressing mechanism.
• IP video includes services like digital television (IPTV), digital video transport services for broadcast customers, videoconferencing, video streaming, and peer-to-peer video distribution.
• Real-time IP video and streaming video services place stringent requirements on the network. Such services are sensitive to network imperfections such as latency, loss and jitter. These imperfections may be caused by network overload conditions or, in some cases, by normal network behavior such as re-convergence of routing.
• Relevant open standards for IP video are MPEG-1, MPEG-2, MPEG-4, H.261, H.263, H.264. Proprietary standards include Windows Media Player WMP9, Real Networks Helix, and Apple QuickTime.
• Transport and network protocols that support real-time delivery of video include MMS, RTSP and HTTP.
• Today, most video is sent best-effort — there is no specific quality of service mechanism that is widely used.
• Current plans call for a real-time MPLS class, which will provide suitable quality of service for VoIP and for real-time video.
Video Compression Standards: MPEG, Moving Picture Experts Group, is a family of International Standards used for digital compression of audio-visual information. The MPEG family of standards includes MPEG-1, MPEG-2 and MPEG-4, formally known as ISO/IEC-11172, ISO/IEC-13818 and ISO/IEC-14496.
MPEG-1 is meant primarily for stored interactive video applications (CD-ROM). It can deliver full-motion color video at 30 frames per second from a CD-ROM. The MPEG standard also addresses the compression of the audio information at 64, 96, 128, and 192 Kbps and uses time stamps for synchronization between audio and video. MPEG-1 was standardized in October 1992.
MPEG-2 is targeted at TV transmission and other applications with data rates of 4 Mbps and more. MPEG-2 features very high picture quality. MPEG-2 supports interlaced video formats, increased image quality, and other features aimed at HDTV. MPEG-2 is compatible with MPEG-1, i.e., an MPEG-2 decoder can also decode MPEG-1 bit streams. MPEG-2 is used on all consumer DVD’s.
The MPEG-4 video standard was originally developed for low-bit-rate applications (< 384 Kbps) for CIF (352 x 288) resolution. However, it widened its scope (through the use of so-called “profiles”) so that it also addresses applications at bit rates up to 2 Mbps and furthermore, up to 38.4 Mbps, with resolutions up to 1,920 x 1,088. The initial version of MPEG-4 was released in 2000.
The current version, which focuses on video and audio presentation, can deliver video at rates as low as 5 Kbps. It can also adjust its throughput to fit available bandwidth. An advanced version that adds interactive elements was released in early 2001 with further enhancements including intellectual property management and protection released in mid-2002.
Transport Protocols widely used for Video: There are three popular streaming protocols: HTTP, Microsoft Media Server (MMS) and real-time Streaming Protocol (RTSP). HTTP is being supported by almost all streaming servers. It is firewall-friendly but has a larger delivery overhead.
MMS is a proprietary protocol supported only by Microsoft streaming server. RTSP is supported by all major streaming servers and is gaining popularity in the market. The default streaming protocol used in Microsoft Windows Media platform is now RTSP, not MMS. The market trend is going toward the RTSP and HTTP protocols.
Video/Media on Demand Servers: Major streaming servers use the “client-server” model for content delivery. In this model a viewer sends a request to a streaming server to start a streaming service. To scale up the centralized delivery model, all three major streaming servers and some networking vendors (e.g., Novell Volera Excelerator, Cisco ACNS and Network Appliance Net Cache) provide proxy/caching products where hierarchical delivery architecture can be created to relieve the load of a streaming server. A new delivery architecture using Grid Computing and P2P technologies (such as Kontiki OMN) is gaining market attention due to its potential significant savings of streaming infrastructure cost.
Multicast Video Services: Traditionally, IP networks have supported point-to-point, or unicast, communication. IP multicast enables the efficient network distribution of traffic from a single source to multiple receivers, and is thus a promising technology for supporting one-to-many video applications. Deployment and use of IP multicast, first proposed in the late 1980s, has been slow in coming. Among the reasons cited for this slow deployment are the complexities of specifying and implementing scalable and secure multicast routing protocols, the lack of adequate network management capabilities and the lack of critical applications to drive deployment.
In recent years, progress has been made in overcoming these challenges, and we are starting to see significant deployment of IP multicast in enterprise networks (including the Internet backbone.) The most common uses of IP multicast today are for distribution of market data by financial companies (Merrill Lynch, JPMorgan Chase, among others), support of internal all-employee web casts (as in UGN), and software distribution.
Existing deployments of multicast are generally supported by Protocol Independent Multicast (PIM), the dominant multicast routing protocol in use today. While the analogy does not hold completely, PIM serves a similar purpose for multicast routing as OSPF serves for unicast routing.
PIM has several variants, including Dense Mode (DM), Sparse Mode (SM), and Bi-directional (BIDIR), and Single Source Multicast (SSM). PIM is responsible for creating multicast distribution trees within the network. These variants differ in the manner in which they create these trees, resulting in tradeoffs in the use of network resources, state in the routers, and optimality of the trees themselves.
PIM-SM is the most widely used variant today. Use of PIM-BIDIR and PIM-SSM is increasing. PIM-DM is not widely used.
While global service providers are using multicast internally on the UGN, and while multicast has been deployed in the past on the backbone, Global carriers have neither provided any significant multicast service to customers nor carried much multicast traffic on its backbone. Carriers are currently deploying multicast VPN (MVPN) in its backbone and access routers and plans to provide service to several customers by the end of the year.
In the near term, carriers’ primary use of multicast will be to support MVPN service for its enterprise VPN customers. In the future, it may also be useful in supporting the transport of broadcast quality IP video across the network. Uses include distribution of video content from a single national distribution point to many (tens or hundreds) of regional distribution points. This is similar to how satellite technology is used to transmit to cable head ends and other local distributors of content, and the transmission from a local distribution point to consumers — akin to distribution from a cable head end to end users.
Peer-to-peer Services: Jupiter Research predicts that around 60 percent of households in the U.S. will have broadband access by year 2012. As a result, it is now feasible to distribute video and audio data by utilizing the large amount of idle bandwidth at the end users. Several peer-to-peer (P2P) protocols have been proposed for this purpose. The most popular P2P protocol on the Internet is Bit Torrent. According to a recent CNN report, Bit Torrent traffic represents 60% of all P2P traffic on the Internet in 2014.
Unlike traditional P2P protocols such as Napster, Gnutella, and Kazaa, Bit Torrent organizes peers sharing the same file into a P2P network and uses a tits-for-tats incentive mechanism to distribute the file efficiently. By dividing a file into small chunks, a peer in Bit Torrent can download multiple parts of a video file in parallel. Recent studies have indicated that P2P traffic has surpassed web traffic to become the most dominant traffic on the Internet. Currently, most content in P2P networks is either non-copyright videos or pirated goods. An important future direction will incorporate Digital Rights Management (DRM) into the P2P distribution process.
There is a concerted effort on the part of regional telecommunications companies to compete with incumbent video service providers by building out a fiber optic network for providing all-digital television services (IPTV) to consumers. This includes broadcast television, as well as video on demand.
These services will be provided over a network that offers varying bandwidths for the last hop to the home, varying from optical to copper. Efficient use of the last mile is enabled by streaming only a small set of channels to the end user at any given time. A channel change by the consumer is transmitted back to the local office, which then switches the streamed video material. This is in contrast to current analog RF cable architecture, where all channels are transmitted to each endpoint. Growing bandwidth demands, driven for example, by HDTV programming will require a similar change on part of cable providers as well.
All digital video to the home is expected to provide the consumer with more flexibility than is currently possible with a set-top box with a built-in digital video recorder — it will be possible for the consumer to view television programs according to their customized schedule, rather than a schedule dictated by the broadcast network.
Many broadcasters are interested in transporting video material over a digital network, as opposed to analog satellite transmission or in some cases, physical transportation (shipping videotapes/DVD’s). Some drivers for advanced video transport services are improvements in coverage, cost, transmission efficiency, a desire for greater redundancy in the network, monitoring of the state of the network, peer-to-peer program exchange capabilities, and the need of digital rights management security technologies.
Telco Video/IPTV Service Providers:
• AT&T announced in January 2005 that it is conducting technical trials of Microsoft IPTV. The project is called Lightspeed, and it is FTTC technology.
• Comcast is testing Microsoft IPTV technology in areas of Seattle and Tacoma. Motorola has been supplying the set-top boxes for the trial, which involves about 6,000 end users.
• Qwest has about 46,000 homes connected with VDSL for its Qwest Choice TV product, a first-generation IPTV service operating in parts of Denver, Phoenix, and Omaha. It has also laid fiber to RidgeGate, a new housing subdivision near Denver.
Qwest says it will install FTTN only “where it makes sense for the company, such as in certain new developments where green field conditions exist.” Qwest will not be offering IP video. It is using the same technology as the cable companies – modulated RF video signals for transmission over fiber.
• AT&T is in the midst of it the rollout for its Project UVERSE FTTN/FTTP fiber network or Lightspeed. Project UVERSE is in field trials in employees’ homes and was launched in 2007. AT&T plans to use Microsoft TV for functions like interactive electronic program guides, video-on-demand, and DVR. SBC also made a deal with 2Wire in a joint venture to build a set-top box that can receive both IPTV and satellite programming and support DVR functions. SBC also is partnering with Yahoo! for the portal interface, and Alcatel and Microsoft for the integration between network hardware and IPTV software.
• Time Warner hopes to adopt all digital or simultrans within two to three years. It has tested switched broadcast video on digital channels in 2005 using Scientific-Atlanta set-top boxes and BigBand Networks switches. Time Warner will use a generic Ethernet switch in future launches; an RFP for that switch was released.
• Verizon plans to use Microsoft’s IPTV in its FTTP-based FiOS service to deliver video-on-demand and other interactive services. The company is also working with Motorola on the set-top box and TVN Entertainment and Turner Broadcasting System for video-on-demand content. Verizon will initially deploy an RF overlay video network with a path to IPTV based on the Microsoft platform over its FiOS network.
• Microsoft – Microsoft TV is an end-to-end software platform that includes video content ingestion software, server software that manages video assets, set-top box middleware, and consumer applications like VOD.
• Microsoft is collaborating with Alcatel on an end-to-end IPTV solution, combining Alcatel’s hardware infrastructure with its IPTV middleware platform. Through this alliance, the companies will perform video delivery processes, including application development, content and DRM integration, quality of service management, and network integration. Alcatel has an IPTV platform called Open Media Platform (OMP) that enables the provisioning of consumer-facing apps.
• OpenTV – OpenTV supplies middleware software for digital TV services including personal video recorder (PVR) and interactive TV for cable, satellite, telecommunications, and network operators.
Streaming Server Vendors – Each vendor supports RTSP and HTTP streaming protocols:
• Microsoft – Microsoft Media on Demand servers; Windows Media Player 10
• Real Networks – Helix
• Apple – QuickTime or Darwin Streaming Server
Centralized Head end Video Server Vendors:
• Arroyo Video Solutions
• BigBand Networks
Broadcast Video Equipment Vendors:
• BigBand Networks
• Broadsoft Networks
• Cisco Systems
• Tandberg Television
Secure Content Distribution Vendors:
Set-Top Box Vendors (CPE):
• Cisco Systems
End-to-End Solutions Vendors:
• Zhone Technologies
• Multimedia over Cable Alliance – consisting of consumer electronics companies (i.e. Entropie, Motorola, and Toshiba), cable MSOs (i.e., Comcast), and satellite vendors (i.e, EchoStar), MoCA is developing specifications and products to deliver DVD video and gaming services throughout the home at speeds of up to 270 Mbps over the existing coax cable.
• MPEG – Moving Picture Experts Group, a working group of ISO/IEC in charge of the development of standards for coded representation of digital audio and video.
• MPEG Industry Forum – an organization to further the adoption of MPEG Standards, by establishing them as well-accepted and widely used standards among creators of content, developers, manufacturers, providers of services, and end users.
• IETF – Working groups relevant to Multicast and Streaming include: IETF Multicast, Multi-Cast Address Allocation; Integrated Services over Specific Link Layers; Inter-Domain Multicast Routing; Multicast Extensions to OSPF; Multicast Source Discovery Protocol; Protocol Independent Multicast; Audio/Video Transport; Integrated Services; Multiparty Multimedia Session Control; and Resource Reservation Setup Protocol.
Video will be a critical service and key revenue generator in the coming years, especially when direct and fierce competition with Multi-Service Operators (i.e., Cable TV Operators) is inevitable. However, the infrastructure and operation cost of providing video over IP is still quite high. Scaling up HD quality video services to millions of customers will be a problem.
Major bottlenecks to widespread deployment of IP video are a paucity of edge bandwidth and the impact of normal and abnormal network events. These events include route re-convergence or network overloading on the quality experienced by the end-user. End-user quality is not only a function of transport, but also of the equipment on the customer’s premises and the way this equipment is configured. Thus, there is also a need for well-understood and generally accepted quality parameters that can be monitored in the network. These parameters can be used as a basis for service level agreements between service providers as well as service providers and end-users.