First, the definition of VOD VOD is video on demand, which is a new media mode in recent years. This technology is a combination of computer technology, network communication technology, multimedia technology, television technology and digital compression technology. VOD technology enables people to freely order video programs and information in the program library on the computer or TV according to their own interests without using video recorders, DVD players and cable TV. It is an interactive system that can freely choose the content of video programs, and it is an application field that software developers around the world pay close attention to in recent years. The essence of VOD is that information users actively obtain multimedia information according to their own needs, which is the biggest difference from information release: initiative and selectivity. In a sense, this is a way for information recipients to improve and develop themselves according to their own needs. This way will increasingly meet the deep needs of consumers of information resources in today's information society. It can be said that VOD is the mainstream way to obtain multimedia video and audio information in the future. The concept of video-on-demand will expand rapidly in the field of information acquisition, and it has an infinitely broad development prospect. Secondly, VOD system consists of four parts: video server, communication network, client equipment and production management system. (1) video server: stores a large amount of video program information; Processing user's interactive command information and sending video data (2) Communication network: backbone network, which requires higher bandwidth and connects the video server and the subnet of the production management system; the next level network is used as the backbone network to transmit information to all client devices (3) Client devices, which complete the playing of video program information; Provide user interface and receive interactive command information (4) Production management system: complete the editing and production of video programs; Management of video database; User management application field of VOD system VOD system can be widely used in computer local area network, wide area network, broadband integrated access network, cable TV network and so on, and has broad application prospects in many fields. 1) KTV, film and television songs, karaoke bars, cable TV stations, multi-functional Internet cafes, multimedia classrooms on campus networks, multimedia libraries, multimedia information release, electronic libraries, government enterprises 5) interactive tour guides and exhibition systems 6) interactive multimedia exhibition airports, railway stations, theaters and exhibition halls, museums, advertising malls and department stores 7) hotels and restaurants 8) residential quarters 9) internal training of enterprises/ 0) Introduction and features of VOD karaoke system for pathological analysis and telemedicine (diagnosis) in distance education hospital 1 System introduction and features: Traditional karaoke bars use DVD players and LD discs to play songs, which are manually operated by operators. This method needs to buy a large number of DVD players and LD discs, and the staff salary and management expenses are expensive. It is an inevitable development trend for karaoke bars to realize automatic on-demand through computers. VOD karaoke scheme provides a karaoke computer song ordering system based on video-on-demand technology, which introduces advanced multimedia network technology, multimedia database technology and multimedia compression technology, and adopts video server instead of traditional DVD player to realize comprehensive computer automatic control of song ordering and service management. Second, the main features of the system: (1) digital transmission: it is realized by computer local area network, and digital signal transmission is adopted without laying audio and video cables; (2) Automatic playback: unattended automatic main control room, avoiding human error, saving the purchase cost of DVD player and DVD player and a lot of personnel management expenses; (3) Information appliances: provide karaoke terminals for KTV private rooms, provide high-quality video images and rich and beautiful operation interfaces, and support a variety of song ordering methods, such as number of people, words and singers. , including a lot of photos and other beautiful images of the singer. (4) Consumption management: KTV private rooms can be audited by ordering food through the karaoke ordering terminal, plus the front desk, singles desk, bar kitchen, cashier, management desk and information desk. Form a strong catering consumption management system. System description: 1. Video server is the core of VOD system, and its main functions are: (1) storage tube for a large number of songs and programs; (2) program retrieval and update; (3) processing the user's on-demand request; (4) Continuous and stable video stream output; (2) Each DVD karaoke song in the disk library occupies about 6544 disk space. The capacity of the disk library can be expanded as needed. 3. Program production is used to manage the music library and import new programs from VCD and DVD discs. 4. The karaoke song-ordering terminal VOD uses a special karaoke song-ordering terminal as the client-side on-demand equipment of KTV rooms. Its main features are as follows: (1) Digital video is required to have no signal attenuation and distortion through computer network; (2) The operation interface and program playback are displayed on the monitor and TV respectively, and the song ordering operation will not be affected when singing; (3) Built-in professional video decompression card. Ensure excellent audio-visual quality (4) You can use a mouse, a remote controller or a keypad, and the operation is simple and quick (5) You can order drinks and settle accounts through the karaoke terminal in the private room. 5.( 1) The editing system copies and compresses various video sources (such as VCD, DVD, video tape, etc.). ) to the video library and generate the program menu at the same time. (2) The program or menu data of the karaoke on demand terminal is connected with the database of the video server through the local area network. (3) The video server plays the video program or program menu to the corresponding karaoke song-ordering terminal according to the command of the broadcast control system, and the decoder of the digital video playing card MPE- 1 converts it into multi-channel analog AV signals, which are directly connected to the TV. 6. Other (1) systems are based on 100M switched Ethernet. (2) Bars and kitchens need to be equipped with bill printers. Epson TM series is recommended. (3) The cashier needs to be equipped with a printer. It is recommended to use VOD karaoke system with automatic paper feeding. Function: 1 Features: 1. Song ordering management-provides a variety of song ordering methods: (1) number: enter the song number in the song ordering book; (2) Singers: List all the songs of the designated singers for selection, and provide a large number of beautiful photos of singers; (3) Song title: choose a language, and. You can easily find the song with the specified song title. (4) Song type: Sort songs by TV songs/movie songs/children's songs/opera songs/folk songs/nostalgic songs. (5) New songs: Select the latest pop songs. (6) Ranking: automatically generate a leaderboard according to the number of songs sorted. (7) Chorus: the list of chorus songs is flexible. (8) Advertising pictures and welcome words can be displayed in the private room. (9)