《多媒体通信技术(第七章终端).ppt》由会员分享，可在线阅读，更多相关《多媒体通信技术(第七章终端).ppt（84页珍藏版）》请在三一文库上搜索。
1、第七章 多媒体通信终端,程控教研室,课堂主要内容,基于多媒体计算机的多媒体通信终端,基于特定网络的多媒体通信终端,多媒体通信终端概述,多媒体通信终端相关标准,视频会议,视频监控,概念,多媒体通信终端：是指接收、处理和集成各种媒体信息，并通过同步机制将多媒体信息同步地呈现给用户，同时具有交互功能的通信终端。,多媒体终端的构成,搜索模块,编解码模块,同步 模块,准备模块,执行模块,用户,网络,应用协议,同步协议,接口协议,输入交互部分,再编辑,接口,终端的特点,交互性,同步性,多媒体通信终端的特点,集成性,B,多媒体通信终端的关键技术,多媒体通信终端的相关标准,ITU制定的H.32x系列标准,IE
2、TF制定的用于IP的SIP协议,H.323标准,H.323是ITU-T的一个标准簇，它于1996年由ITU-T的第15研究组通过，最初叫做“工作于不保证服务质量的LAN上的多媒体通信终端系统”。 1997年底通过了H.323V2，改名为“基于分组交换网络的多媒体通信终端系统”。 H.323V2的图像质量明显提高，同时也考虑了与其他多媒体通信终端的互操作性。 1999年5月ITU-T又提出了H.323的第三个版本。,介于传输层与应用层之间,应 用 层,H323 层,传 输 层,网 络 层,数 据 链 路 层,物 理 层,协议体系,H.323协议站 (TCP/IP),Audio/Video App
3、lication,C branch=z9hG4bK776asdhds Max-Forwards: 70 To: Bob From: Alice ;tag=1928301774 Call-ID: a84b4c76e66710pc33.yyy.edu CSeq: 314159 INVITE Contact: Content-Type: application/sdp Content-Length: 142,v=0 o=Alice 2897654321 2897654321 IN IP4 10.0.0.1 s=Phone Call c=IN IP4 192.168.0.1 t=0 0 m=audio
4、 49170 RTP/AVP 0 a=rtpmap:0 PCMU/8000,SIP Headers,INVITE sip:bobzzz.edu SIP/2.0 Via: SIP/2.0/UDP pc33.yyy.edu;branch=z9hG4bK776asdhds Max-Forwards: 70 To: Bob From: Alice ;tag=1928301774 Call-ID: a84b4c76e66710pc33.yyy.edu CSeq: 314159 INVITE Contact: Content-Type: application/sdp Content-Length: 14
5、2,SIP Headers,INVITE sip:bobzzz.edu SIP/2.0 Via: SIP/2.0/UDP pc33.yyy.edu;branch=z9hG4bK776asdhds Max-Forwards: 70 To: Bob From: Alice ;tag=1928301774 Call-ID: a84b4c76e66710pc33.yyy.edu CSeq: 314159 INVITE Contact: Content-Type: application/sdp Content-Length: 142,Method 即 命令,Request URI,SIP 協定版本,S
6、IP Headers,INVITE sip:bobzzz.edu SIP/2.0 Via: SIP/2.0/UDP pc33.yyy.edu;branch=z9hG4bK776asdhds Max-Forwards: 70 To: Bob From: Alice ;tag=1928301774 Call-ID: a84b4c76e66710pc33.yyy.edu CSeq: 314159 INVITE Contact: Content-Type: application/sdp Content-Length: 142,所有經過的SIP設備都會被列在這裡 branch用來識別不同的連線分支,在
7、所有 SIP Requests中都是必要的欄位,INVITE sip:bobzzz.edu SIP/2.0 Via: SIP/2.0/UDP pc33.yyy.edu;branch=z9hG4bK776asdhds Max-Forwards: 70 To: Bob From: Alice ;tag=1928301774 Call-ID: a84b4c76e66710pc33.yyy.edu CSeq: 314159 INVITE Contact: Content-Type: application/sdp Content-Length: 142,最多可以被幾個Server轉傳,SIP Head
8、ers,在所有 SIP Requests之中除了INFO都是必要的欄位,INVITE sip:bobzzz.edu SIP/2.0 Via: SIP/2.0/UDP pc33.yyy.edu;branch=z9hG4bK776asdhds Max-Forwards: 70 To: Bob From: Alice ;tag=1928301774 Call-ID: a84b4c76e66710pc33.yyy.edu CSeq: 314159 INVITE Contact: Content-Type: application/sdp Content-Length: 142,目的地位址,SIP He
9、aders,在所有 SIP Requests中都是必要的欄位,INVITE sip:bobzzz.edu SIP/2.0 Via: SIP/2.0/UDP pc33.yyy.edu;branch=z9hG4bK776asdhds Max-Forwards: 70 To: Bob From: Alice ;tag=1928301774 Call-ID: a84b4c76e66710pc33.yyy.edu CSeq: 314159 INVITE Contact: Content-Type: application/sdp Content-Length: 142,來源位址 虛擬的隨機亂數 (當作是
10、ID使用),SIP Headers,在所有 SIP Requests中都是必要的欄位,James Polk 20050503,INVITE sip:bobzzz.edu SIP/2.0 Via: SIP/2.0/UDP pc33.yyy.edu;branch=z9hG4bK776asdhds Max-Forwards: 70 To: Bob From: Alice ;tag=1928301774 Call-ID: a84b4c76e66710pc33.yyy.edu CSeq: 314159 INVITE Contact: Content-Type: application/sdp Conte
11、nt-Length: 142,在網域內獨一無二的識別碼,SIP Headers,在所有 SIP Requests中都是必要的欄位,INVITE sip:bobzzz.edu SIP/2.0 Via: SIP/2.0/UDP pc33.yyy.edu;branch=z9hG4bK776asdhds Max-Forwards: 70 To: Bob From: Alice ;tag=1928301774 Call-ID: a84b4c76e66710pc33.yyy.edu CSeq: 314159 INVITE Contact: Content-Type: application/sdp Con
12、tent-Length: 142,遞增的序號,SIP Headers,在所有 SIP Requests中都是必要的欄位,James Polk 20050503,INVITE sip:bobzzz.edu SIP/2.0 Via: SIP/2.0/UDP pc33.yyy.edu;branch=z9hG4bK776asdhds Max-Forwards: 70 To: Bob From: Alice ;tag=1928301774 Call-ID: a84b4c76e66710pc33.yyy.edu CSeq: 314159 INVITE Contact: Content-Type: appl
13、ication/sdp Content-Length: 142,直接可以路由到來源位址的完整網域名稱或IP位址,SIP Headers,INVITE sip:bobzzz.edu SIP/2.0 Via: SIP/2.0/UDP pc33.yyy.edu;branch=z9hG4bK776asdhds Max-Forwards: 70 To: Bob From: Alice ;tag=1928301774 Call-ID: a84b4c76e66710pc33.yyy.edu CSeq: 314159 INVITE Contact: Content-Type: application/sdp
14、Content-Length: 142,用來描述附加的訊息主體格式 (如果有的話),SIP Headers,INVITE sip:bobzzz.edu SIP/2.0 Via: SIP/2.0/UDP pc33.yyy.edu;branch=z9hG4bK776asdhds Max-Forwards: 70 To: Bob From: Alice ;tag=1928301774 Call-ID: a84b4c76e66710pc33.yyy.edu CSeq: 314159 INVITE Contact: Content-Type: application/sdp Content-Length
15、: 142,用來描述附加的訊息主體的內容長度 (Octets),SIP Headers,INVITE sip:bobzzz.edu SIP/2.0 Via: SIP/2.0/UDP pc33.yyy.edu;branch=z9hG4bK776asdhds Max-Forwards: 70 To: Bob From: Alice ;tag=1928301774 Call-ID: a84b4c76e66710pc33.yyy.edu CSeq: 314159 INVITE Contact: Content-Type: application/sdp Content-Length: 142,SIP
16、Headers,Session Description Protocol (SDP),描述多媒體連線的協定 RFC 2327 簡單，可以擴充的，以文字為基礎 SIP Offer/Answer Model RFC 3264 在每一行 欄位=值 值 值 欄位是一個字元 (大小寫有差別) 等號兩旁不可以有空格 分為Session和Media層次,SDP的結構內容,Session 層次 (從 v=這一行開始) Session Name 主動發起的一端 活動時間 Media 層次 (從 m=這一行開始) 媒體形式 video, audio, Port number 傳輸層協定 RTP/UDP/IP, H
17、.320, . 媒體格式 H.261 video, MPEG video, .,SDP的範例,SDP的欄位,v= (protocol version) 例如: v=0 o= (owner/creator and session identifier) o= Username 不可以含有空格 Session id 和version 建議使用Network Time Protocol (NTP)的時間戳記來確保值的唯一性 例如: o=john 2887654326 2887654307 IN IP4 10.1.2.3 s= (session name string) 例如: s=SDP Semin
18、ar t= (start time and stop time) 例如: t=2887654321 2887654310(通常設為0),為必要欄位,SDP的欄位,m= (media name and transport address) m= m= / 例如: m=video 49170/2 RTP/AVP 0 audio, video, application, data and control“ RTP/AVP - the IETFs Realtime Transport Protocol using the Audio/Video profile carried over UDP UDP
19、 RTP/AVP RFC 3551 e= (email address) 例如: e=johnyyy.edu (John Doe) 或者 e=John Doe p= (phone number) 例如: p=+886-4-2496-1356 或者 p=+886 4 2496 1356,u-law PCM, single channel, audio sampled at 8KHz,SDP的欄位,c= (connection information) c= 例如: c=IN IP4 224.2.17.12/127 通常這個連線位址是一個 class D的 IP 群播位址, / 例如: c=IN
20、IP4 224.2.1.1/127/3 指的是多個c=IN IP4 224.2.1.1/127, c=IN IP4 224.2.1.2/127, c=IN IP4 224.2.1.3/127 如果這一個會議連線不是群播, 則它可以搭配額外的屬性欄位決定是完整網域位址或單一IP位址等等,SDP的欄位,i= (session information) u= (URI of description) b= (bandwidth information) z= (time zone adjustments) k= (encryption key) a= (zero or more session at
21、tribute lines) r= (zero or more repeat times),SIP Methods: INVITE, ACK and BYE,Alice,Bob,INVITE,INVITE sip:bob192.168.10.20 SIP/2.0 Via: SIP/2.0/TCP pc33.yyy.edu ;branch=z9hG4bK776asdhds Max-Forwards: 70 To: Bob From: Alice ;tag=1928301774 Call-ID: a84b4c76e66710pc33.yyy.edu CSeq: 314159 INVITE Cont
22、act: Content-Type: application/sdp Content-Length: 142 (Alices SDP not shown),SIP Methods: INVITE, ACK and BYE,INVITE,200 OK,Alice,Bob,SIP/2.0 200 OK Via: SIP/2.0/TCP pc33.yyy.edu ;branch=z9hG4bKnashds8 ;received=10.1.3.33 To: Bob ;tag=a6c85cf From: Alice ;tag=1928301774 Call-ID: a84b4c76e66710pc33.
23、yyy.edu CSeq: 314159 INVITE Contact: Content-Type: application/sdp Content-Length: 131 (Bobs SDP not shown),SIP Methods: INVITE, ACK and BYE,Alice,Bob,ACK,ACK sip:bob192.168.10.20 SIP/2.0 Via: SIP/2.0/TCP pc33.yyy.edu;branch=z9hG4bKnashds8 Max-Forwards: 70 To: Bob ;tag=a6c85cf From: Alice ;tag=19283
24、01774 Call-ID: a84b4c76e66710pc33.yyy.edu CSeq: 314159 ACK Content-Length: 0,SIP Methods: INVITE, ACK and BYE,Alice,Bob,SIP Methods: INVITE, ACK and BYE,Alice,Bob,BYE,BYE sip:alicepc33.yyy.edu SIP/2.0 Via: SIP/2.0/TCP 10.1.3.33;branch=z9hG4bKnashds8 Max-Forwards: 70 From: Bob ;tag=a6c85cf To: Alice
25、;tag=1928301774 Call-ID: a84b4c76e66710pc33.yyy.edu CSeq: 231 BYE Content-Length: 0,SIP Methods: INVITE, ACK and BYE,Alice,Bob,200 OK,SIP/2.0 200 OK Via: SIP/2.0/TCP 192.168.10.20 From: Alice ;tag=1928301774 To: Bob ;tag=a6c85cf Call-ID: a84b4c76e66710pc33.yyy.edu CSeq: 231 BYE Content-Length: 0,Ali
26、ce,Bob,SIP Proxy “server.zzz.edu”,透過Proxy Server,INVITE sip:bobzzz.edu/TCP SIP/2.0 Via: SIP/2.0/TCP pc33.yyy.edu ;branch=z9hG4bK776asdhds ;received=10.1.3.33 Max-Forwards: 70 To: Bob From: Alice ;tag=1928301774 Call-ID: a84b4c76e66710pc33.yyy.edu CSeq: 314159 INVITE Contact: Content-Type: applicatio
27、n/sdp Content-Length: 142 (Alices SDP not shown),Alice,Bob,透過Proxy Server,SIP Proxy “server.zzz.edu”,INVITE sip:bob192.168.10.20/TCP SIP/2.0 Via: SIP/2.0/TCP server.zzz.edu ;branch=z9hG4bK4b43c2ff8.1 ;received=192.168.10.1 Via: SIP/2.0/TCP pc33.yyy.edu ;branch=z9hG4bK776asdhds ;received=10.1.3.33 Ma
28、x-Forwards: 69 To: Bob From: Alice ;tag=1928301774 Call-ID: a84b4c76e66710pc33.yyy.edu CSeq: 314159 INVITE Contact: Content-Type: application/sdp Content-Length: 142 (Alices SDP not shown),James Polk 20050503,Alice,Bob,透過Proxy Server,SIP Proxy “server.zzz.edu”,Alice,Bob,透過Proxy Server,SIP Proxy “ser
29、ver.zzz.edu”,Alice,Bob,透過Proxy Server,SIP Proxy “server.zzz.edu”,Alice,Bob,透過Proxy Server,SIP Proxy “server.zzz.edu”,Alice,Bob,透過Proxy Server,SIP Proxy “server.zzz.edu”,Alice,Bob,透過Proxy Server,SIP Proxy “server.zzz.edu”,Alice,SIP Methods: REGISTER,REGISTER 註冊 SIP URI 稱之為 Address of Record (AOR) 把一個
30、AOR和現在可以連繫得上的實際位址對應連接在一起 讓UA可以收到 SIP的訊息 UAs可以利用下列方法向伺服器註冊 手動設定 Address-of-Record Multicast 224.0.1.75,SIP Registrar Server,Alice,SIP Methods: REGISTER,SIP Registrar Server,SIP/2.0 200 OK Via: SIP/2.0/TCP pc33.yyy.edu ;branch=z9hG4bk2l55n1; received=10.1.3.33 To: Alice ; tag=a6c85e3 From: Alice ;tag=
31、283074 Call-ID: a84b4g96te10pc33.yyy.edu CSeq: 31862 REGISTER Contact: Contact: Expires: 3600 Contact-Length: 0,200 (OK) 回應包含一連串的Contact Expires Header 告知 UA註冊的有效期限,REGISTER 通常是需要經過密碼認證的,Call Forking,Alice,yyy.edu,zzz.edu,Notebook,Bobs,Mobile phone,Bobs,同時嚮，看哪一個先接！,Alice,Bob,SIP Methods: MESSAGE (RF
32、C3428),MESSAGE 以 近乎 即時的方式傳送 存在在 MIME的主體中 不會啓始新的 dialogs 訊息之間沒有任何關聯 不可以超過 1300 bytes,MESSAGE sip:bobzzz.edu SIP/2.0 Via: SIP/2.0/TCP pc33.yyy.edu ;branch=z9hG4bK776asegma Max-Forwards: 70 To: Bob From: Alice ;tag=1928301774 Call-ID: a84b4c76e66710pc33.yyy.edu CSeq: 22756 MESSAGE Content-Type: text/pl
33、ain Content-Disposition: render Content-Length: 37 Isnt this a great presentation, Bob?,Alice,Bob,SIP Methods: MESSAGE (RFC3428),SIP/2.0 200 OK Via: SIP/2.0/TCP pc33.yyy.edu;branch=z9hG4bKnashds7; received=10.1.3.33 To: sip: sip:bobzzz.edu; tag=a6c85e3 From: aliceyyy.edu ;tag=1928301774 Call-ID: a84b4c76e66710pc33.yyy.edu CSeq: 22756 MESSAGE Content-Length: 0,參考文獻,http:/www.cs.columbia.edu/sip/ “Carrier Grade Voice Over IP” Daniel Collins 出版社: McGraw-Hill ISBN 0071231552 ,