Video on Demand(VOD)

Video VOD is in the 1990s in abroad developed, also known as the "VOD". Not surprisingly, is according to the audience's requirements of broadcast video vod system, the user has clicked the video content, or choice for transmitting the requested users.

introduction

Video on Demand (VOD Video hereinafter rest), also known as interactive TV VOD system, meaning according to users needs corresponding Video program broadcast, fundamentally changed the user past passive watching TV shortage. When you turn on the TV, you can watch ads, not for a particular program in a hurry, always watching vod hope the contents of direct, like play just into his house VCR or VCD of a new film, but you also do not need to buy viedio or VCD dish, also do not need VCR or VCD. This is information technology bring you dreams, it through multimedia network will video program according to the individual intend to households.

Scan widely broadband network applications, VOD closest to people's lives, but its technical difficulty also is the largest. Take common words, highway have, then the car run, VOD application is broadband multimedia network on the markeddest car.

VOD technology not only can be used in telecommunication of broadband network, and can also be used in residential LAN and cable TV broadband network. Now in building intelligent village process, computer network cabling has become an indispensable part of residential users can, by computers, TV sets (with STB), etc. To realize VOD VOD video applications, enrich people's cultural life, Cable TV after two-way transformation, can let the user through cable television network vod television video program.

structure

Server system

The server system mainly consists of video server, archives management server, internal communication subsytem and network interface components. File management server mainly responsible for customer information management, billing, film materials collected and security and confidentiality such tasks. Internal communication subsytem mainly completes server information transfer between film and television, background materials and data exchange. Network interface main realization and exterior network data exchange and provide the user access interface. Video server mainly by storage devices, cache and control management unit composition, the goal is implementation of media data compression and storage, and according to the request for media information retrieval and transmission. Video server with traditional data servers have many significant difference, need to increase many special software and hardware function equipment, to support the business of the special needs. For example: media data retrieval, real-time transmission and information flow of encryption and decryption, etc. For interactive VOD system for, the server system also need to implement real-time request to the user of processing, access permission control, Video Cassette Recorder VCR () function (e.g., fast forward, pause, heavy around, etc.) of the simulation.

Network system

Network system includes main network and local network two parts. Because it is responsible for video information flow real-time transmission, so is the effect of continuous media network service system performance crucial part. Meanwhile, media services system network some investment huge, so when the design should be given not only to the current media application on high bandwidth demand, but also the future development needs and backward compatibility. At present, can be used to establish such service system network physical media are mainly: CATV (cable) of the coaxial cable, optical fiber and twisted-pair cable. And use of network technology is mainly: fast Ethernet, FDDI and ATM technology.

Client systems

At present, according to the different functional requirements and application scenarios, mainly have three VOD system: TVOD, IVOD NVOD,.

NVOD (Near - Video - On - rest), can call its nearest type Video On Demand (vod). This video on demand (vod) way is: multiple video ordinal interval certain time start sending the same content. For example, twelve demand&live every 10minutes to start a send the same two hours of television programs. If you want to watch this TV program may have to wait, but the longest not more than ten minutes, they would choose from their recent starting point for some time to watch. In this way, a video may for many users to share.

TVOD (True Video - On - rest), says it is True Video On Demand (vod), it is True that some namely support put. When the user request, video server will instantly transmit user needs to the video content. If there is another user demand, this same video server will immediately for him to start another transmission of the same material streaming video. Nevertheless, once streaming video began on continuous play, will go on until the end. This way, each video to a user service.

IVOD (Interactive Video - On - rest), called Interactive Video On Demand (vod). It than the previous two ways are largely the improvement. It can not only support namely point is put, and still can let users on demand&live on interactive control. At this time, the user can like VCR as traditional operation, realizing program broadcast, suspended, or reversed, fast forward and automatic search, etc.

Only use the corresponding terminal equipment, users can with some kind of service or service providers to link and interoperability. In VOD system, need TV and STB (Set - the top Box), in some special system, may also need a equipped with large capacity hard disk to store the computer from video server film files. Client systems, in addition to involve the corresponding hardware device, also be fitted with relevant software. For instance, in order to meet the user's multimedia interactive needs and must be of client system interface are modified. In addition, in continuous media, media stream buffer management, audio and video data synchronization, network broadcasting interrupted the interrupt and coordination of all need to carry on the full consideration.

Visible VOD service although very seductive, but its implementation technology is not a root "easy to chew bones." But as the network technology, computer technology and storage technology is developing rapidly, and the masses of users fully enjoy the fun of VOD day has not far away. By that time, demand users as long as remote controller, a single click, can the horse. watching and appreciation of their favorite program, and can adjust the projected progress, speed, etc. The emergence of VOD makes television can be made into a random access to information media, more like a book or a piece of newspaper, can browse, can adjust, no longer bureau be confined to a time and date and fixed programs restrictions.

Although, VOD the first appeared in order to better satisfy the users for independent watch video program demand, but as the VOD technology advances, its wide application in mass culture and business operation mode will be strong impact. VOD can not only provide end users with various types of media information flow, to enlarge its channels of information, enrich people's spiritual life, And in hospitals, hotels, aircraft etc. The place of entertainment, the company's staff training, long-distance market survey, the advertising business of the company, etc will gradually full of VOD new applications.

Emerge background

In the current network video transmission process, usually require users will audio, video download file to the local computer, then playback. This method while keeping the Internet on multimedia information transmission becomes possible, but it has also brought the three prominent problems:

Real grow independently

(1) because must download the multimedia information, and the multimedia information data quantity is often quite, in the current ordinary users access rate lower case, a very short video clips may need to download a long time.

(2) the must take programs downloaded to a local computer to play, this must take the local computer storage resources.

(3) copyright problems. Because users will audio and video files downloaded to the hard disk, may want to these data, then again spread production unit of the intellectual property right may be damaged.

In this context, the "streaming" appeared. It drew lessons from the computer itself to improve the cache files using the running speed of the way, consider playing buffer to solve the placement service quality problem. Streaming audio and video will be animation, and other multimedia through special compression way into a compressed package, video server by computer users to continuous and real-time transmission. In the use of streaming transmission mode in the system, the user need not like the streaming broadcast until the entire document that all after the download is complete to see the specific content, just after a few seconds or dozens of seconds start-up time delay can use corresponding player on compression of the video, audio, animation such streaming multimedia file decompression after the play, the remainder of the multimedia file will also in the server continue the download. This kind of using "streaming" thought of multimedia transmission, called streaming media.

So far, Internet use more multimedia formats: (1) the vod video AnBoShi Real Netwoks company

The Real system; (2) Microsoft Windows Media Technology company, (3) Apple company QuickTime, they are currently online streaming media transmission system three mainstream.

1, streaming media content production:

(1) turn archives/transcoding software: can turn ordinary format audio, video, or animation Media files by compression converted to flow server on streaming format file, it flow is the most basic manufacture software, actually is also an Encoder (Encoder), common software: Real Producer and Windows Media Encoder

(2) streaming media editing software: convection media files of editing, often with turn archives/transcoding bundled together.

(3) synthesis software: use synthesis software, can will various pictures, sounds, words, video, slide or web synchronization and synthesize a streaming media files. Common software: RealShow, RealPresenter and Windows MediaAuthor.

(4) : streaming media programming software system to provide SDKS can make the developers of system and secondary development. Using the SDK, developers can usually develop streaming data types, and create the new client applications, custom streaming media system. The SDK (Software circumstances Kit)

Classified introduction

According to the different functional requirements and application scenarios, mainly have three VOD system: TVOD, IVOD NVOD,.

NVOD (Near - Video - On - rest), can call its nearest type Video On Demand (vod). This video GNI vod system

Kind of video on demand (vod) way is: multiple video ordinal interval certain time start sending the same content. For example, twelve demand&live every 10minutes to start a send the same two hours of television programs. If you want to watch this TV program may have to wait, but the longest not more than ten minutes, they would choose from their recent starting point for some time to watch. In this way, a video may for many users to share. TVOD (True Video - On - rest), says it is True Video On Demand (vod), it is True that some namely support put. When the user request, video server will instantly transmit user needs to the video content. If there is another user demand, this same video server will immediately for him to start another transmission of the same material streaming video. Nevertheless, once streaming video began on continuous play, will go on until the end. This way, each video to a user service.

IVOD (Interactive Video - On - rest), called Interactive Video On Demand (vod). It than the previous two ways are largely the improvement. It can not only support namely point is put, and still can let users on demand&live on interactive control. At this time, the user can like VCR as traditional operation, realizing program broadcast, suspended, or reversed, fast forward and automatic search, etc.

Only use the corresponding terminal equipment, users can with some kind of service or service providers to link and interoperability. In VOD system, need TV and STB (Set - the top Box), in some special system, may also need a equipped with large capacity hard disk to store the computer from video server film files. Client systems, in addition to involve the corresponding hardware device, also be fitted with relevant software. For instance, in order to meet the user's multimedia interactive needs and must be of client system interface are modified. In addition, in continuous media, media stream buffer management, audio and video data synchronization, network broadcasting interrupt interrupt and coordination problem of hotel rooms VOD video VOD system

Need to undertake due consideration.

Visible VOD service although very seductive, but its implementation technology is not a root "easy to chew bones." But as the network technology, computer technology and storage technology is developing rapidly, and the masses of users fully enjoy the fun of VOD day has not far away. By that time, demand users as long as remote controller, a single click, can the horse. watching and appreciation of their favorite program, and can adjust the projected progress, speed, etc. The emergence of VOD makes television can be made into a random access to information media, more like a book or a piece of newspaper, can browse, can adjust, no longer bureau be confined to a time and date and fixed programs restrictions.

Although, VOD the first appeared in order to better satisfy the users for independent watch video program demand, but as the VOD technology advances, its wide application in mass culture and business operation mode will be strong impact. VOD can not only provide end users with various types of media information flow, to enlarge its channels of information, enrich people's spiritual life, And in hospitals, hotels, aircraft etc. The place of entertainment, the company's staff training, long-distance market survey, the advertising business of the company, etc will gradually full of VOD new applications.

Based on IP VOD

Due to network bandwidth limits, especially WAN (WAN), the bandwidth limits in WAN on two-way video VOD VOD system

High-speed data transmission still not mature, so we're dealing with here based on IP video VOD (VOD) technology, is refers with Ethernet as VOD transmission platform, realize the local scope TVOD (real VOD) technology. Because we hereby Ethernet platform and can also offer, such as Internet access, traditional data business, IP telephone, picture-tel, TV conference and so on many kinds of value-added services, so we'll be at an IP (here refers to Ethernet) based on the platform of exchange implements multiple business exchange, which help people in small range can realize the information, and it also high-speed interactive for future to realize information high-speed interactive laid a foundation. Future with optical fiber technology and further development of technology for router IP protocol and various kinds of further perfecting and will eventually realize "information superhighway". So, is it possible for us to realize high speed in a WAN data transmission and ensure all kinds of real-time service quality, also only that by now we can say we have entered a complete information society. A, realization based on IP of VOD difficulty

1. Based on IP real-time exchange quality of service (QoS)

Because IP using data packaging, packet-switched form, simultaneously also allow packet size is different. Therefore, real-time data transmission cannot guarantee quality, this is mainly because packet caused by collision network delay time uncertainty caused, so in network bandwidth requirements is very big, meanwhile to the real-time requirement is high on the video transmission cannot guarantee its quality of service (QoS).

2. Video server processing ability

Video server has a lot of kinds, generally speaking in its support for user quantity and based on the system of classification, basically have the following several forms.

(1) based on general computer video server

Such video server were quite simple. From the development view, which usually is the primary products, function is simple, the number of users, limited support also limited (50 households or so). Due to its low price, so in small application domain has particular market.

(2) based on advanced video server workstations

Based on the video server is a senior workstation large computer manufacturer of a few production in the computer USES its advantage by the high performance based on computers, add some support video data access related hardware, and perform some of the optimization of system, in order to achieve general video server functions. They tend to moderate scale of network support (50 ~ 1000 door), but its high price make general user daunting.

(3) based on special hardware platform of video server

Based on the special hardware platform of video server is some hardware manufacturers use special realization of hardware H800 VOD video WK - visual (VOD) system

Frequency according to visit. Due to the use of special hardware realized to video data access, and emphatically resolve its mass storage issues, so no matter from speed, or from storage capacity is the former two video server and incomparable. But it also has its disadvantages. First, since it adopted the special-purpose hardware and solved the mass storage issues, so good quality is good price, so I decided to its high prices. Second, since they are some hardware vendors developed by the dependence of hardware, very strong, so its generality is very poor, has limited its development, general multi-purpose in large network applications.

To sum up, video server still has a lot of troubles near places (such as price, handling ability, generality, etc), but with the development of technology, will eventually maturity and the day isn't too long.

3. Mass data storage

Due to film the volume of data is very large (1.2 ~ 1.5 GB), and thus save film became a very big problem, namely mass data storage problem.

Above these problems, it is for VOD some technical difficult problem. In view of the above questions, we in the existing technology based on hierarchical structure launched a distributed system as our solution, it is based on IP (here refers to Ethernet) technology as the foundation of the solution.

Status quo future

With the media services digital and interactive degree rise increasingly, compression technology progress prompted bandwidth is lowered continually, today's market is experiencing a major changes. With increasing, consumer business network access bandwidth gained widespread popularity. These trends and excellent telecommunications performance and rich media content of fusion is to bring the vod video business transmission earth-shaking changes. Techniques become more mature users can easily visit content, therefore we can begin expect via cable and mobile equipment ultra-high anytime experience the quality of video and other rich media types. In addition, content owners are also seeking more effective new ways, so that more widely spread its content and in as many ways profit. Content usability, and technical ability and omnipresent high-speed telecom infrastructure brings a "perfect storm" has blown open to large-scale, high income vod video of a rapidly changing the gate.

But VOD growth will surely give fixed network operators to bring many challenges and opportunities, such as: the VOD video congestion Internet market size and revenue growth rate statistical management, the content location services, billing, and recommend engine, store, and timely delivery. Want to make a dream come true, various aspects auxiliary infrastructure must all implementation and must meet the following factors: the high-speed access and transmission, feasible server solution, sufficient and widely distributed users with network storage, media processing, delivery routing diversity, content processing and QoS (flow and congestion management). Meanwhile, for the vod content and media content delivery optimization framework must also be carried out and complete function.

The key factor: media

Media, technology and telecommunication fields is undergoing changes, can ensure the vod video in the next few years become media transmission in the field of important power. Which media as a whole industry as rich as key will provide various equipment available content. Of course, in competition has the white-hot media sales market, media must be coordinated, elaborate layout planning and careful analysis. Through the thorough understanding each user to purchase historical records, download preferences and preferred technology and delivery mode can maximize the future sales potential. Equally important and key is, vod video started in market plays an increasingly important role. Media now increasingly aware vod video information retrieval media is the ability to war reliable and long-term Allies. In addition, it can promote the voice, video and data "triple broadcasting business" delivery.

Key factors no.2: technology

Technology in video vod delivery plays equally important role. At present, the content stored in user hand storage device (usually DVD). And technology and market acceptance and decided VOD can become good reality, so an interesting change has shown. The past is stored at the client content is to network transplantation, then from one or multiple servers to extract content and on-demand sent to users. So you can simplify aspects, such as the large capacity storage arrays, equivalence between complex interactive server, strong packet processing capabilities, data collection and billing algorithm and able to transmit increasingly rich media content of network. Of course, if not timely, accurately put inside starlight infinite telecommunication level video vod system topological structure

Let delivered to the user hand, all this is empty talk. Measurable quality of service (QoS) must be assured and, in the network and the dependence of processor transmission environment, flow management is very important. Must be able to design and implement in the worst cases for its offer to guarantee the work area delivery architecture.

Key factors no.3: telecom

Telecommunications is whole delivery blueprint priority. The three industries fundamentally relies on two other industries, telecoms particularly important. Support away from their reliable broadband infrastructure, again the rich content, again complex function again powerful data collection, storage and billing models, user is also water months, mirror in flowers. Telecommunication field from a series of recent progress has many aspects to remould network role, especially for the vod content.

Of course, the biggest change from the rigid, based on TDM networks to more flexible IP network irreversible development. Although telecoms industry transformation is still in the early stages, but the situation will soon change, the whole service provider network has begun to IP and MPLS transformation. Is worth mentioning IMS, because it in the near future, will become the vod video's centre of gravity. The IMS as to the 3GPP first mobile devices provide content a way, it is now more to be seen as in various network transmission of multimedia content of backbone technology platform. IMS promising: as long as universally deployment, service providers can through any network, use any access to global anywhere any user of any device provide any content, and can according to network database to store the user first-selected way for billing. This magical function caught flow as a business with VOD video prerequisite of message. Can analyze and use client preference, consistently high QoS guarantee, and can according to user rather than service provider of the need to provide content of media, technology and telecoms infrastructure could be called perfection. But, service delivery the road ahead is still twists and turns.