Time-shifted playback of network television technology

With the development of multimedia technology and the popularity of broadband networks, streaming media technology has become more and more widely used, although streaming media live broadcast technology is positioned to provide real-time streaming services. However, the current user needs are also diverse. How to solve the contradiction between the real-time performance of the live broadcast system and the user's personalized playback needs, the "time shift" playback technology is put on the agenda by streaming media technology vendors.

Technical overview

In real time, the live broadcast can be played back at any time in the past, that is, the live broadcast time shift. This technology is mainly used in emerging network TV stations.

Since the traditional TV signal is limited by the transmission and broadcast control modes, the live broadcast of the traditional TV can only be pushed in one direction - the viewer cannot perform real-time playback of the broadcasted live content. This will make the audience unhappy at some point - because the damn work phone has delayed a wonderful World Cup goal. With the development of coding technology, streaming media technology and network bandwidth, IPTV and emerging network TV stations have emerged. The most familiar to everyone is: China Internet TV.

The principle of live time shifting technology: through the code transcoding system, the ordinary TV signal is output as a stream (such as MPEG-4 format), sliced ​​and indexed, and then streamed and distributed via the streaming media server, and finally synchronized. Output to various terminals (television, PC monitor, mobile phone). The live content that the end user sees can be played back at will. The advantage of live time shifting technology: its system transmission is based on the HTTP protocol, which can span the enterprise firewall and cover more user groups. At present, Xiamen Radio and Television Network TV Station adopts VIEWGOOD (Eternal) to realize the unique and efficient way. The combination of infinite storage and real-time stream caching enables seamless integration of recording and broadcasting. Users can choose the channel, bit rate, and time point at will, watch any program at any time, and return to the live spot at any time. The dedicated Xiamen Radio and Television Network TV player has improved the user's HD experience.

Technology Architecture

In view of the common problem in the existing live broadcast system, VIEWGOOD designed a live streaming server for the Xiamen Broadcasting and Television Group that supports the time shift function: Clear Live Server. The server uses an innovative time, calculation method to achieve real-time time shifting.

The WebLIVE live server architecture is shown in Figure 1. The acquisition and encoding process is used for real-time collection and encoding of multimedia data; the data receiving process is used to receive data from the data collection and encoding process; the WebLIVE server process is used to manage data of all channels, and submit data to the playback stream process according to the request. The play stream process sends data to the player according to the indication of the HTTP communication process; the HTTP communication process is used to process the HTTP request of the WebPlayer player, and the processing result is sent to the player board process as a control message. The computing power, network bandwidth and disk I/O capability of the server can easily become the bottleneck of the system. Because the amount of HTTP communication data is small, the data acquisition and encoding process and the HTTP communication process can be run in separate servers, and the other three. The process runs on the same server. The server is named as the collection server, the master server, and the playback server according to the process name and function. Because a single master server can manage multiple streaming servers, the system can be flexibly deployed to achieve centralized control of all users to support multiple encoding formats and multiple clients. At the same time, the system can make full use of the bandwidth of multiple playback servers to increase the number of concurrent systems.

According to this deployment, in the live broadcast process, the client first obtains the live server and channel related information from the web server, and submits a channel request to the main control server. After the main control server processes the request, the control information is first sent to the streaming server, and then The streaming server sends data to the player accordingly.

Technology Architecture

Defining HD Network TV Technology Based on Seamless Time-Shift Playback

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