Of: State Administration of Radio Monitoring Center Jian-Gang Wang
IPTV is an interactive network TV, is a use of broadband cable networks to home users, including a variety of interactive digital television services, including new technology. In recent years, use of broadband networks, broadband cable television, wireless video transmission of new media value-added services, like there is network TV, mobile TV, TV phone, etc., they set the Internet, multimedia, communications and other technologies in one, its transmission, the terminal vary, but the similarities are VideoOver IP.
An IP TV features IP TV with clear images and the realization of the media and the consumer interaction. IP TV uses the highly efficient video compression technology, 786Kb / s video transmission bandwidth can close its television ratings DVD standard. Select the user, IP TV can use different compression ratio, producing content for different bandwidth. It can use broadcast (live) form can also be used on-demand format. So, the user can be no time limit to watch their favorite programs. Can repeatedly watch a particular program. IP TV is not only a communications tool, it also has the inherent interactive networks and feedback. IP TV to provide digital TV programs, video IP phones, DVD / VCD player, visit the Internet, e-mail, and a variety of online information consulting, entertainment (eg games), education and business functions (such as video conferencing) and other multimedia services.
IPTV and traditional broadband Internet access with the biggest difference is the terminal mode. Traditional methods can only be limited to use of the Internet PC, and IPTV terminal can be either PC, can also be a TV, which determines the scope of IPTV is quite broad.
IPTV and Digital TV the biggest difference is, IPTV broadband network to transmit digital TV signals, but the traditional digital TV is transmitted via closed-circuit lines. Thus the "digital television" only available means of broadcasting can not be achieved on demand; and IPTV only capable of receiving broadcast signals, but also to achieve the user's interaction with the media, but also very easy to television services and Internet browsing, e-mail, and the consult a variety of online information, entertainment, education and business functions together.
IPTV business features and functions of the broadcasting industry with the impact of IP phones, as did the impact of traffic on the fixed network, operators can not because the IP phone service alternative to fixed telephone services is not to develop it. As radio and television authorities?? State Administration of Radio Film and Television to take an active and effective management and monitoring measures will be unfavorable factors into favorable factors for the development of the IPTV business to occupy an important position.
2 how to adapt to the needs of the development of IP TV
For the next generation of streaming media business development, which areas should SARFT regulation? My view the following main aspects:
* Actively participate in standards development and standardization work;
* Find a streaming media programs meet the production, distribution, monitoring of the new model;
* The establishment of a set of content regulation, technology monitoring system.
3 Video over IP monitoring methods and indicators After packing
MPEG video streams transmitted through the Ethernet network will occur during the timing jitter distortion. VideooverIP The key is to measure the technical monitoring and testing network jitter and packet loss situation. We use as MDI (MediaDeliveryIndex) measure for testing and measurement. MDI applies to any kind of transmission through the network transport stream, and can be used to VideoOver IP system fault monitoring and alarm loss.
1. Timing distortion causes MPEG video transport streams over Ethernet and Internet package exchange, will have a certain timing on the distortion. The distortion is due to the timing and the target packet sent result of the different timing source. Packet delay in the network illustrated in Figure 1, some packets arrive than the time delay prior to their transfer to short, similar to the diagram in the first group of packages; while some of the packets arrive at the time than they longer delay before transmission, similar to the figure of the second package situation. Under the package with the ideal timing comparison of the situation, we can define the packet jitter conditions (ideal and the actual packet arrival time difference of arrival time).
Figure 1 packet in the network delay
2. Temporal distortion effects and solutions
For the receiver (IP codec) for the flow rate to the normal code to display the video image, it must pass a buffer to adjust the input rate of change in timing, but the size of the buffer required to store sufficient receive data and can ensure that the receiver at the time of broadcast video images have delayed too long data packets stored up. This system is contradictory, on the one hand requires enough memory to handle all of the network buffer delay, on the other hand too much memory buffer when the video would cause more delay. For a fixed-size buffers, the regulatory network jitter, a maximum value will be determined. Either buffer overflow or buffer will be uploaded when the video image caused by the suspension or the improved image quality.