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sdpinfo
liwenfeng edited this page Feb 26, 2019
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3 revisions
const sdpstr = "v=1\r\n" +
// o=<username> <sess-id> <sess-version> <nettype> <addrtype> <unicast-address>
"o=- 4327261771880257373 2 IN IP4 127.0.0.1\r\n" +
//session
"s=-\r\n" +
// 会话的起始时间和结束时间，0代表没有限制
"t=1 1\r\n" +
// 表示需要共用一个传输通道传输的媒体，通过ssrc进行区分不同的流。如果没有这一行，音视频数据就会分别用单独udp端口来发送.
"a=group:BUNDLE audio video\r\n" +
// WMS是WebRTC Media Stream简称;
// 这一行定义了本客户端支持同时传输多个流，一个流可以包括多个track.
// 一般定义了这个，后面a=ssrc这一行就会有msid,mslabel等属性.
// This lines gives an unique identifier for the WebRTC Media Stream (WMS) during the PeerConnection’s life. This identifier that will be used in the a=msid attributes for each m-line belonging to a specific Media Stream (in our case both audio and video m-lines). This means that the RTP media stream (identified by the SSRC field present in every RTP packet) belongs to that media stream and that it is a track of that media stream. It is an explicit association of an individual RTP media stream to the MediaStream WebRTC object. For more info about this refer to draft-ietf-mmusic-msid
"a=msid-semantic: WMS xIKmAwWv4ft4ULxNJGhkHzvPaCkc8EKo4SGj\r\n" +
// -------------------------------- 【Stream Description部分】 --------------------------------
// -------------------------------- audio部分 --------------------------------
// m意味着它是一个媒体行.
// m=audio说明本会话包含音频，9代表音频使用端口9来传输，但是在webrtc中现在一般不使用，如果设置为0，代表不传输音频,
// UDP/TLS/RTP/SAVPF是表示用户支持来传输音频的协议，udp,tls,rtp代表使用udp来传输rtp包，并使用tls加密
// SAVPF代表使用srtcp的反馈机制来控制通信过程
// 后面的111 103 104 9 102 0 8 106 105 13 110 112 113 126表示本会话音频支持的编码，后面几行会有详细补充说明.
"m=audio 9 UDP/TLS/RTP/SAVPF 111 103 104 9 0 8 106 105 13 110 112 113 126\r\n" +
// 表示你要用来接收或者发送音频使用的IP地址.
// webrtc使用ice传输，不使用这个地址
"c=IN IP4 0.0.0.0\r\n" +
// 用来传输rtcp的地址和端口，webrtc中不使用
"a=rtcp:9 IN IP4 0.0.0.0\r\n" +
// 下面2行是ice协商过程中的安全验证信息
"a=ice-ufrag:ez5G\r\n" +
"a=ice-pwd:1F1qS++jzWLSQi0qQDZkX/QV\r\n" +
// dtls协商过程中需要的认证信息
"a=candidate:1 1 UDP 33554431 35.188.215.104 59110 typ host\r\n" +
"a=fingerprint:sha-256 D2:FA:0E:C3:22:59:5E:14:95:69:92:3D:13:B4:84:24:2C:C2:A2:C0:3E:FD:34:8E:5E:EA:6F:AF:52:CE:E6:0F\r\n" +
// 代表本客户端在dtls协商过程中，可以做客户端也可以做服务端, 参考rfc4145 rfc4572
"a=setup:actpass\r\n" +
"a=connection:new\r\n" +
// 前面BUNDLE行中用到的媒体标识
"a=mid:audio\r\n" +
// 指出要在rtp头部中加入音量信息，参考 rfc6464
"a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level\r\n" +
// 指出是双向通信，另外几种类型是recvonly,sendonly,inactive
"a=sendrecv\r\n" +
// 指出rtp,rtcp包使用同一个端口来传输
"a=rtcp-mux\r\n" +
// 下面十几行都是对m=audio这一行的媒体编码补充说明，指出了编码采用的编号，采样率，声道等
"a=rtpmap:111 opus/48000/2\r\n" +
"a=rtcp-fb:111 transport-cc\r\n" +
// 下面一行对opus编码可选的补充说明,minptime代表最小打包时长是10ms，useinbandfec=1代表使用opus编码内置fec特性
"a=fmtp:111 minptime=10;useinbandfec=1\r\n" +
"a=rtpmap:103 ISAC/16000\r\n" +
"a=rtpmap:104 ISAC/32000\r\n" +
"a=rtpmap:9 G722/8000\r\n" +
"a=rtpmap:0 PCMU/8000\r\n" +
"a=rtpmap:8 PCMA/8000\r\n" +
"a=rtpmap:106 CN/32000\r\n" +
"a=rtpmap:105 CN/16000\r\n" +
"a=rtpmap:13 CN/8000\r\n" +
"a=rtpmap:110 telephone-event/48000\r\n" +
"a=rtpmap:112 telephone-event/32000\r\n" +
"a=rtpmap:113 telephone-event/16000\r\n" +
"a=rtpmap:126 telephone-event/8000\r\n" +
// cname用来标识一个数据源，ssrc当发生冲突时可能会发生变化，但是cname不会发生变化，也会出现在rtcp包中SDEC中，用于音视频同步
"a=ssrc:3510681183 cname:loqPWNg7JMmrFUnr\r\n" +
"a=ssrc:3510681183 msid:xIKmAwWv4ft4ULxNJGhkHzvPaCkc8EKo4SGj 7ea47500-22eb-4815-a899-c74ef321b6ee\r\n" +
"a=ssrc:3510681183 mslabel:xIKmAwWv4ft4ULxNJGhkHzvPaCkc8EKo4SGj\r\n" +
"a=ssrc:3510681183 label:7ea47500-22eb-4815-a899-c74ef321b6ee\r\n" +
// -------------------------------- video部分 --------------------------------
"m=video 9 UDP/TLS/RTP/SAVPF 96 98 100 102 127 125 97 99 101 124\r\n" +
"c=IN IP4 0.0.0.0\r\n" +
"a=connection:new\r\n" +
"a=rtcp:9 IN IP4 0.0.0.0\r\n" +
"a=ice-ufrag:ez5G\r\n" +
"a=ice-pwd:1F1qS++jzWLSQi0qQDZkX/QV\r\n" +
"a=candidate:1 1 UDP 33554431 35.188.215.104 59110 typ host\r\n" +
"a=fingerprint:sha-256 D2:FA:0E:C3:22:59:5E:14:95:69:92:3D:13:B4:84:24:2C:C2:A2:C0:3E:FD:34:8E:5E:EA:6F:AF:52:CE:E6:0F\r\n" +
"a=setup:actpass\r\n" +
"a=mid:video\r\n" +
"a=extmap:2 urn:ietf:params:rtp-hdrext:toffset\r\n" +
"a=extmap:3 http://www.webrtc.org/experiments/rtp-hdrext/abs-send-time\r\n" +
"a=extmap:4 urn:3gpp:video-orientation\r\n" +
"a=extmap:5 http://www.ietf.org/id/draft-holmer-rmcat-transport-wide-cc-extensions-01\r\n" +
"a=extmap:6 http://www.webrtc.org/experiments/rtp-hdrext/playout-delay\r\n" +
"a=sendrecv\r\n" +
"a=rtcp-mux\r\n" +
"a=rtcp-rsize\r\n" +
"a=rtpmap:96 VP8/90000\r\n" +
"a=rtcp-fb:96 ccm fir\r\n" +
"a=rtcp-fb:96 nack\r\n" +
"a=rtcp-fb:96 nack pli\r\n" +
"a=rtcp-fb:96 goog-remb\r\n" +
"a=rtcp-fb:96 transport-cc\r\n" +
"a=rtpmap:98 VP9/90000\r\n" +
"a=rtcp-fb:98 ccm fir\r\n" +
"a=rtcp-fb:98 nack\r\n" +
"a=rtcp-fb:98 nack pli\r\n" +
"a=rtcp-fb:98 goog-remb\r\n" +
"a=rtcp-fb:98 transport-cc\r\n" +
"a=rtpmap:100 H264/90000\r\n" +
"a=rtcp-fb:100 ccm fir\r\n" +
//支持丢包重传，参考rfc4585
"a=rtcp-fb:100 nack\r\n" +
"a=rtcp-fb:100 nack pli\r\n" +
//支持使用rtcp包来控制发送方的码流
"a=rtcp-fb:100 goog-remb\r\n" +
"a=rtcp-fb:100 transport-cc\r\n" +
"a=fmtp:100 level-asymmetry-allowed=1;packetization-mode=1;profile-level-id=42e01f\r\n" +
"a=rtpmap:102 red/90000\r\n" +
//支持ULP FEC，参考rfc5109
"a=rtpmap:127 ulpfec/90000\r\n" +
//支持FLEX FEC
"a=rtpmap:125 flexfec-03/90000\r\n" +
"a=rtcp-fb:125 ccm fir\r\n" +
"a=rtcp-fb:125 nack\r\n" +
"a=rtcp-fb:125 nack pli\r\n" +
"a=rtcp-fb:125 goog-remb\r\n" +
"a=rtcp-fb:125 transport-cc\r\n" +
"a=fmtp:125 repair-window=10000000\r\n" +
"a=rtpmap:97 rtx/90000\r\n" +
"a=fmtp:97 apt=96\r\n" +
"a=rtpmap:99 rtx/90000\r\n" +
"a=fmtp:99 apt=98\r\n" +
"a=rtpmap:101 rtx/90000\r\n" +
"a=fmtp:101 apt=100\r\n" +
"a=rtpmap:124 rtx/90000\r\n" +
"a=fmtp:124 apt=102\r\n" +
"a=ssrc-group:FID 3004364195 1126032854\r\n" +
"a=ssrc-group:FEC-FR 3004364195 1080772241\r\n" +
"a=ssrc:3004364195 cname:loqPWNg7JMmrFUnr\r\n" +
"a=ssrc:3004364195 msid:xIKmAwWv4ft4ULxNJGhkHzvPaCkc8EKo4SGj cf093ab0-0b28-4930-8fe1-7ca8d529be25\r\n" +
"a=ssrc:3004364195 mslabel:xIKmAwWv4ft4ULxNJGhkHzvPaCkc8EKo4SGj\r\n" +
"a=ssrc:3004364195 label:cf093ab0-0b28-4930-8fe1-7ca8d529be25\r\n" +
"a=ssrc:1126032854 cname:loqPWNg7JMmrFUnr\r\n" +
"a=ssrc:1126032854 msid:xIKmAwWv4ft4ULxNJGhkHzvPaCkc8EKo4SGj cf093ab0-0b28-4930-8fe1-7ca8d529be25\r\n" +
"a=ssrc:1126032854 mslabel:xIKmAwWv4ft4ULxNJGhkHzvPaCkc8EKo4SGj\r\n" +
"a=ssrc:1126032854 label:cf093ab0-0b28-4930-8fe1-7ca8d529be25\r\n" +
"a=ssrc:1080772241 cname:loqPWNg7JMmrFUnr\r\n" +
"a=ssrc:1080772241 msid:xIKmAwWv4ft4ULxNJGhkHzvPaCkc8EKo4SGj cf093ab0-0b28-4930-8fe1-7ca8d529be25\r\n" +
"a=ssrc:1080772241 mslabel:xIKmAwWv4ft4ULxNJGhkHzvPaCkc8EKo4SGj\r\n" +
"a=ssrc:1080772241 label:cf093ab0-0b28-4930-8fe1-7ca8d529be25\r\n"
- ICE Parameters
a=ice-ufrag:ez5G\r\n
a=ice-pwd:1F1qS++jzWLSQi0qQDZkX/QV\r\n
- DTLS Parameters
a=fingerprint:sha-256 D2:FA:0E:C3:22:59:5E:14:95:69:92:3D:13:B4:84:24:2C:C2:A2:C0:3E:FD:34:8E:5E:EA:6F:AF:52:CE:E6:0F
- ICE Candidates
a=candidate:1 1 UDP 33554431 35.188.215.104 59110 typ host
- stream
容纳多个track的数据结构
- track
一个 track 是一个音频或视频数据流（发送或接收）。它有输入和输出，对于要发送的 track 来说，输入是本地的采集，输出是远端，对于要接收的 track 来说，输入是远端，输出是本地的渲染。