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1, an overview of mobile streaming media service Streaming media content that is transmitted through the data network to the client while the client playback device. Streaming media technology first appeared in the fixed network Communicate In the network audio and video and other multimedia information transmission method of downloading and streaming mainly two kinds of transmission. For the download method, since the large file often requires a lot of storage capacity, while limited by network bandwidth, download often spend a few minutes or even hours, much delay. For streaming, the audio, video or Animation Edge and other documents to download while playing, when sound, and time-based media client player, the file in the background, the rest continue to download from the server, start delay was not only ten times, hundred times shorter, and does not need too much cache capacity, to prevent the user must wait for all the files download from the Internet to view the shortcomings. In the mobile network, streaming media business mainly for GPRS / EDGE, UMTS and so provide high-bandwidth (100kbit / s or more) wireless packet networks, streaming media, according to the different sources of audio and video services into business. At present, based on the fixed network VOD, AOD services, has been widely welcomed by users. In the wireless network, the increase in air interface bandwidth for streaming media services to provide a good basis to carry out, combined with wireless systems from time and place features, making mobile streaming media service more attractive. 2, mobile streaming media service framework Mobile streaming media system network architecture and overall structure of the fixed network similar to streaming media, streaming media server by the client and the corresponding administrative system, the composition of the contents of the cache device. As shown for mobile streaming media service framework map. Mobile Streaming Media Service Framework Figure Complete streaming media business by the streaming media server, streaming media client, the portal (Portal), user management system, the cache server form. The mobile streaming media systems, streaming media server via Gi interface, GGSN is connected with the wireless core network. Portal is to provide more convenient access to streaming media server capabilities. For example, the portal may provide content browsers and search tools. The simplest case, it only contains a Web / WAP page. Streaming media content stored in content server, and streaming media content list of links can be located anywhere on the network. Meanwhile, portal, content provider (CP) to the streaming media server and streaming media cache content, the portal provides authentication and content distribution CP interface. Management system used to store user preferences and device capabilities information is used to control how mobile users to stream media content. Launched streaming services client to connect to their choice of servers, streaming media server can send real-time content. Session Initiation, the streaming media server and management system, in consultation and in accordance with ability to send streaming media information terminals. 3, key technologies 3.1 Streaming Media Transfer Protocol (1) RTP / RTCP protocol RTP (Real-time TransportProtocol) is in the Internet multimedia data streams on a transmission protocol, working one on one or one to many in the transmission case, can provide information and to achieve synchronous flow of time. RTP typically use UDP does not transmit data, it can work over TCP or ATM protocols. When an application starts a RTP session, it will use to two ports, one for RTP port, one as the RTCP port. RTP itself can not transmit data packets in order to provide reliable delivery mechanism, does not provide flow control or congestion control, but on RTCP to provide these services. RTCP (Real-time Transport ControlProtocol) together with RTP to provide flow control and congestion control services. During the RTP session, participants periodically send RTCP packets, these packets contains the number of packets sent, the number of lost packets and other statistical data, the server can be changed dynamically according to the information transmission rate, and even change the payload type . RTP and RTCP to be effectively used in conjunction with feedback, which reduces cost and improves the transmission efficiency is very suitable for online real-time data transmission. (2) Real Time Streaming Protocol RTSP (Real-time Streaming Protocol) RTSP by RealNetworks, Netscape co-sponsored a protocol that defines how to make one to many applications effectively through the IP network to transmit multimedia data. RTSP is the server side and client to establish and control the audio and video streaming protocol on the server side and client-side play, "Remote Control" role, the client can stream audio and video servers for play, pause, fast forward , positioning, recording and other operations. RTSP is an application layer protocol, it must be the bottom of the RTP, RSVP and other protocols as the basis, it can provide a complete Internet streaming service. In the data transmission path and transmission mechanism of selection both follow the underlying RTP or TCP protocol. It is able to unicast and multicast streaming media player to provide high performance, but also to different manufacturers compatible transmitter and receiver applications. (3) Resource Reservation Protocol RSVP (Resource ReserveProtocol) RSVP is the Internet's Resource Reservation Protocol, RSVP uses a portion of network resources (ie bandwidth), to a certain extent, the transmission of streaming media to provide QoS. RSVP runs in the transport layer, are Transmission Control Protocol. The elements of a RSVP sender, receiver and the host or router. Responsible for the recipient know who sent the data to be sent and what kind of QoS; recipient is responsible for sending a notification to the host or router, so they can prepare to receive the data coming out of the host or router is responsible for leaving all the appropriate resources. RSVP protocol are two important concepts of flow and booking. Flow from sender to receiver connected to one or more characteristics of IP packets via the "flow tags" to certification. Sender sends a stream in a path before transmission to the destination information receiver, this information includes the source IP address, IP address and the purpose of a flow specification. This flow specification is the flow rate and delay composition. After the realization of intended receiver, receiver-based model can achieve a distributed solution. 3.2 encoding format (1) video encoding format 3GPPUMTS video media codec specification is IT U-TH.263, PSS is to use the video decoder, but also I am an expert from electronicswholesalesupplier.com, while we provides the quality product, such as China Portable Boombox , MP5 Music Player, Best Portable Notebook,and more.
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