南京師范大學(xué)多媒體原理與技術(shù)教學(xué)課件,南京師范大學(xué),多媒體,原理,技術(shù),教學(xué),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(yù)錄制內(nèi)容的廣播：(2)聲音點(diǎn)播(audio on demand)(3)影視點(diǎn)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(shí)時(shí)電視會(huì)議(group real-time video conferencing)14.1.2 Application Classification1.現(xiàn)場交互應(yīng)用(live interactive applications)2.交互應(yīng)用(interactive applications)3.非實(shí)時(shí)交互應(yīng)用(non-interactive applications)14.1.3 Problems in Application DevelopmentTwo problems to solve in Multimedia Network Application：提高網(wǎng)絡(luò)帶寬(BW)，減少時(shí)延(delay)，減少抖動(dòng)(jitter)。Methods of Audio and Video Storage on InternetWEB Server和流式服務(wù)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(wù)器傳給媒體播放器直接把聲音/電視從WEB服務(wù)器送給媒體播放器直接把聲音/電視從多媒體流放服務(wù)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(wù)器上，或者放在聲音/電視流放服務(wù)器(streaming server)上。對于前一種情況，由Web服務(wù)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(wù)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(yuǎn)程通信網(wǎng)絡(luò)可分成兩類網(wǎng)絡(luò)：線路交換網(wǎng)絡(luò)(circuit-switched networks)和信息包交換網(wǎng)絡(luò)(packet-switched networks)。信息包交換網(wǎng)絡(luò)也稱數(shù)據(jù)網(wǎng)絡(luò)(data networks)。在線路交換網(wǎng)絡(luò)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(luò)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(gè)應(yīng)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(luò)中，發(fā)送端把整個(gè)消息分割成許多小的數(shù)據(jù)塊，經(jīng)過包裝并“貼上”標(biāo)簽之后再發(fā)送到網(wǎng)絡(luò)上。發(fā)送到網(wǎng)絡(luò)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(luò)，提供兩種類型的服務(wù)：無連接服務(wù)(connectionless service)和面向連接服務(wù)(connection-oriented service)。任何一種因特網(wǎng)服務(wù)都必須使用這兩種服務(wù)之一。對這兩種服務(wù)，每個(gè)信息包都帶有目的地址，而交換機(jī)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?