南京師范大學多媒體原理與技術教學課件,南京師范大學,多媒體,原理,技術,教學,課件 Multimedia Network Application and Exchange TechnologyThe applications on the internet can be roughly divided into two kinds,one kind is text data communication,including the file transfer,Email,Telnet,Network News and Web,etc.Another kind is the voice and television image communications.Usually voice communications and image communication network applications are called multimedia networking application.14.1 Multimedia Network Application(1)現(xiàn)場聲音和電視廣播或者預錄制內容的廣播：(2)聲音點播(audio on demand)(3)影視點播(video on demand)，也稱交互電視(Interactive Television)(4)因特網(wǎng)電話(Internet telephony)(5)分組實時電視會議(group real-time video conferencing)14.1.2 Application Classification1.現(xiàn)場交互應用(live interactive applications)2.交互應用(interactive applications)3.非實時交互應用(non-interactive applications)14.1.3 Problems in Application DevelopmentTwo problems to solve in Multimedia Network Application：提高網(wǎng)絡帶寬(BW)，減少時延(delay)，減少抖動(jitter)。Methods of Audio and Video Storage on InternetWEB Server和流式服務器the way of reading voice and video files on client computer 通過WEB瀏覽器把聲音/電視從WEB服務器傳給媒體播放器直接把聲音/電視從WEB服務器送給媒體播放器直接把聲音/電視從多媒體流放服務器傳送給媒體播放器14.2 Methods of Audio and Video storage and getting in the Internet經(jīng)過壓縮的聲音或者電視文件可以放在Web服務器上，或者放在聲音/電視流放服務器(streaming server)上。對于前一種情況，由Web服務器通過HTTP協(xié)議把文件傳送給客戶。對于后一種情況，由流放服務器通過非HTTP協(xié)議把文件傳送給客戶。Sending Audio and Video From Web Server to Media Player Through Web BrowserSending Audio and Video Directly to Media Player Form Web Server.Sending the Voice/Video from exile server to multimedia media player directly14.3 Information Exchange Technology on the Internet遠程通信網(wǎng)絡可分成兩類網(wǎng)絡：線路交換網(wǎng)絡(circuit-switched networks)和信息包交換網(wǎng)絡(packet-switched networks)。信息包交換網(wǎng)絡也稱數(shù)據(jù)網(wǎng)絡(data networks)。在線路交換網(wǎng)絡中，雙方交換消息期間通道上的全部資源(如鏈路帶寬等)都被租用，而在信息包交換網(wǎng)絡中雙方交換消息期間不租用通道上的資源，也就是不保留資源，而是根據(jù)需要來使用資源，交換的信息包往往需要等待可用資源。14.3.2 Circuit-SwitchingCircuit-Switching characteristics:at the beginning of communication,physical connection has been by established by line exchange center of,and the maintain time depends on the needs of message exchange.14.3.3 Packet Switching通常人們把任何一個應用數(shù)據(jù)塊稱為消息(message)。在現(xiàn)代的信息包交換(packet switching)網(wǎng)絡中，發(fā)送端把整個消息分割成許多小的數(shù)據(jù)塊，經(jīng)過包裝并“貼上”標簽之后再發(fā)送到網(wǎng)絡上。發(fā)送到網(wǎng)絡上的這種數(shù)據(jù)包裹稱為信息包(packet)。A Simple Packet Switching Network14.3.5 Connection-Oriented Service and Connectionless Service因特網(wǎng)通常叫做TCP/IP網(wǎng)絡，提供兩種類型的服務：無連接服務(connectionless service)和面向連接服務(connection-oriented service)。任何一種因特網(wǎng)服務都必須使用這兩種服務之一。對這兩種服務，每個信息包都帶有目的地址，而交換機就按照信息包的目的地址來發(fā)送信息包的。14.3.6 Network ClassificationPractice and thinkingWhats the difference of multimedia communication applications and data communications applications On the network?Illustrate multimedia network application characteristics.Using dictionaries or technical reference books to help understand the meaning of packets.Summarize the characteristics of circuit-switching,packet switching and message exchanges.what is the difference of connection-oriented services and connectionless service?