What is Video on Demand?

Video on demand was developed abroad in the 1990s. It is called "Video on Demand" in English, so it is also called "VOD". As its name implies, it is a video-on-demand system that plays programs according to the requirements of the audience, and transmits the video content clicked or selected by the user to the requested user. Video-on-demand services are emerging media methods in recent years. They are the result of the integration of computer technology, network communication technology, multimedia technology, television technology and digital compression technology.

That is, the corresponding video program is played according to the user's needs, which fundamentally changes the user's lack of passively watching TV in the past. When you turn on the TV, you can skip the advertisement and not hurry up for a certain program. You can directly request the content you want to watch at any time, just like playing a new movie just put in your home VCR or VCD player, but you do nt You need to buy a video tape or VCD disc, and you don't need a VCR or VCD player. This is the dream that information technology brings to you. It sends video programs to millions of households through the multimedia network according to individual wishes.

Looking at the application of broadband networks, VOD is closest to the lives of ordinary people, but its technical difficulties are also the greatest. In the words of ordinary people, if there is a highway, there must be a car running. VOD application is the most prominent car on the broadband multimedia network.

VOD technology can be used not only in the broadband network of telecommunications, but also in the broadband network of local area network and cable television. Under construction now

The video-on-demand system is mainly composed of a film source library system, a streaming media service system,

During network video transmission, users are usually required to

According to different functional requirements and application scenarios, there are mainly three VOD systems: NVOD, TVOD, IVOD.

NVOD (Near-Video-On-Demand) , which can be called the nearest on-demand TV. This

due to

As media services become more digital and interactive,

As VOD becomes more popular and service providers, technology designers and media owners continue to merge,

Front-end processing system

The front-end processing system is generally composed of

The VOD video server must run the corresponding software to coordinate various actions; at the same time provide a friendly user interface. It should have the following characteristics:

(1) Can store at least several hundred hours of video programs.

(2) If a user responds to VOD

The development from a single server model to a peer-to-peer model is accompanied by market demand, but even the peer-to-peer model also faces challenges. The biggest challenge is the lack of delivery managed by the service provider, and the network itself faces challenges. To this end, we need a completely new solution-in fact a mixture of the three solutions mentioned above. This is a workaround that allows server units in a VOD network to share storage and processing resources. This technique is called Peer-Assisted Video-on-Demand.

P2P video playback

Point-to-point auxiliary video-on-demand is sometimes called Multiple Source Streaming VOD (VOD). It is a complex but extremely efficient architecture for transmitting unicast video content. In a multi-source streaming system, the original video stream is divided into multiple video blocks and then transmitted over the network, similar to the message being divided into packets before being transmitted over the IP network. If implemented correctly, it can not only improve fault tolerance, eliminate bottlenecks, significantly improve the use of available bandwidth, but also support significantly increased playback speeds. For successful implementation, a multi-source stream scheduler (MSS) needs to be deployed. The MSS receives stream blocks from different servers such as a proxy server or a peer server, sorts the video blocks appropriately, and then sends seamless, constant block rate video streams to the client device. MSS of course also faces its own

Video server

challenge. Changes in data block transmission will cause the MSS buffer to underflow, which will cause playback hunger and playback jitter. Chip-based algorithms more or less help alleviate this problem, but ensuring predictable (and billable) QoS requires stronger control. Because it relies on multiple servers to send video streams to a single client at the same time, this architecture has many advantages, not only is it highly fault-tolerant, but it can also redirect business flows as needed, thereby avoiding network hardware failures or congestion that affects services. In addition, the architecture supports high-resolution video transmission and simultaneous sessions of multiple video streams. This model also allows redundant data to be sent as a precautionary measure to improve overall service quality.

In short, video-on-demand was developed in the 1990s. With the popularity of global IPTV equipment, the continuous enrichment of playable movie content, the continuous update of electronic products with IP connectivity, and the continued growth of the mobile TV market, video-on-demand will also Usher in a period of rapid growth. The 2008 Olympic Games promoted the rapid growth of P2P video playback platforms. Point-to-point networks are becoming the main video distribution mechanism in IP networks, and the technology elements of modern VOD networks are gradually reducing the cost of network and service delivery, improving bandwidth utilization efficiency, and improving QoS levels. Facing the vast market of video-on-demand, both equipment vendors and service providers will be an era where opportunities and challenges coexist.