通过 WebRTC 共享屏幕很容易
2021-04-25 本文已影响0人
老瓦在霸都
简介
网络会议中常用的屏幕共享功能使用
WebRTC 提供的 getDisplayMedia API 就能轻松实现，接口如下
var promise = navigator.mediaDevices.getDisplayMedia(constraints);
MediaDevices 接口的 getDisplayMedia 方法提示用户选择并授予将显示屏幕或其部分（如浏览器窗口和标签页）的内容捕获为 MediaStream 的权限。然后，可以使用媒体流录制 API 录制， 或作为 WebRTC 会话的一部分传输所生成的媒体流。这个媒体流传输到网络的对端，这样就可以共享屏幕的内容了。
例如
async function startCapture(displayMediaOptions) {
let captureStream = null;
try {
captureStream = await navigator.mediaDevices.getDisplayMedia(displayMediaOptions);
} catch(err) {
console.error("Error: " + err);
}
return captureStream;
}
示例1
- HTML 文件
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<!-- 省略引入的 JS 和 CSS -->
<body>
<!-- <a href="https://github.com/walterfan/webrtc-primer"><img style="position: absolute; top: 0; left: 0; border: 0; z-index: 1001;" src="https://s3.amazonaws.com/github/ribbons/forkme_left_darkblue_121621.png" alt="Fork me on GitHub"></a>
-->
<nav class="navbar navbar-default navbar-static-top">
</nav>
<div class="container">
<div class="row">
<div class="col-lg-12">
<div class="page-header">
<h1>WebRTC example of Desktop Sharing </h1>
</div>
<div class="container" id="details">
<div class="row">
<div class="col-lg-12">
<p>Click the button to open or close connection</p>
<div>
<button class="btn btn-default" autocomplete="off" id="startButton">Share Something</button>
</div>
<br/>
</div>
<div class="col-lg-12">
<div class="col-lg-6">
<video id="localVideo" autoplay playsinline muted></video>
</div>
</div>
</div>
<hr>
<div class="footer">
</div>
</div>
<script type="text/javascript" src="js/desktop_sharing_demo.js"></script>
</body>
</html>
- JS 文件
'use strict';
// Polyfill in Firefox.
// See https://blog.mozilla.org/webrtc/getdisplaymedia-now-available-in-adapter-js/
if (adapter.browserDetails.browser == 'firefox') {
adapter.browserShim.shimGetDisplayMedia(window, 'screen');
}
const gdmOptions = {
video: {
cursor: "always"
},
audio: {
echoCancellation: true,
noiseSuppression: true,
sampleRate: 44100
}
}
function handleSuccess(stream) {
startButton.disabled = true;
const video = document.querySelector('video');
video.srcObject = stream;
// demonstrates how to detect that the user has stopped
// sharing the screen via the browser UI.
stream.getVideoTracks()[0].addEventListener('ended', () => {
errorMsg('The user has ended sharing the screen');
startButton.disabled = false;
});
}
function handleError(error) {
errorMsg(`getDisplayMedia error: ${error.name}`, error);
}
function errorMsg(msg, error) {
const errorElement = document.querySelector('#errorMsg');
errorElement.innerHTML += `<p>${msg}</p>`;
if (typeof error !== 'undefined') {
console.error(error);
}
}
const startButton = document.getElementById('startButton');
startButton.addEventListener('click', () => {
navigator.mediaDevices.getDisplayMedia(gdmOptions)
.then(handleSuccess, handleError);
});
if ((navigator.mediaDevices && 'getDisplayMedia' in navigator.mediaDevices)) {
startButton.disabled = false;
} else {
errorMsg('getDisplayMedia is not supported');
}
测试
点击 share 按键，可以选择 为文本 还是 运动共享，后者的帧率会高点。然后再选择屏幕，应用或标签页。
示例2
服务器端
使用 nodejs + socket.io 充当web服务器，并用来传递 sdp
代码：https://github.com/walterfan/webrtc_remote_sharing
启动命令
node screen_share_server.js
[2021-04-21T20:18:41.018] [INFO] screen_share - screen shares server listen on https://localhost:8183
客户端还是 html + JavaScript
详细代码：
- https://github.com/walterfan/webrtc_primer/blob/main/examples/screen_share_demo.html
- https://github.com/walterfan/webrtc_primer/blob/main/examples/js/screen_share_client.js
测试
将 getDisplayMedia 得到的媒体流 MediaStream 通过 PeerConnection 传送给对方
- 张三进入会议室 "Join room"
- 李四进入会议室 "Join room"
- 张三分享屏幕 "start share"
本地屏幕
- 李四就会看到分享的屏幕内容
远端屏幕
注意我们需要观察 RTP 包的荷载内容，所以要关掉 SRTP ，只用 RTP 来传输
出于测试目的， Chrome Canary 及 Chrome Developer 有一个选项 --disable-webrtc-encryption 可以关掉 SRTP
在我的 macbook 上步骤如下：
cd /Applications/Google\ Chrome\ Canary.app/Contents/MacOS/
./Google\ Chrome\ Canary --disable-webrtc-encryption
于是在创建 RTP 连接时的 SDP 就从:
m=video 9 RTP/SAVPF 96 97 98 99 100 101 102 121 127 120 125 107 108 109 35 36 124 119 123 118 114 115 116
就变成了
m=video 9 RTP/AVPF 96 97 98 99 100 101 102 121 127 120 125 107 108 109 35 36 124 119 123 118 114 115 116
完整sdp如下
- offer sdp 消息：
{
type: 'offer',
sdp: 'v=0\r\n' +
'o=- 2151254633287699884 2 IN IP4 127.0.0.1\r\n' +
's=-\r\n' +
't=0 0\r\n' +
'a=group:BUNDLE 0 1\r\n' +
'a=extmap-allow-mixed\r\n' +
'a=msid-semantic: WMS VLvw0Ec4NwiXKVzTZyzl1m5aSLGW9EPe50Mz\r\n' +
'm=audio 9 UDP/TLS/RTP/SAVPF 111 103 104 9 0 8 106 105 13 110 112 113 126\r\n' +
'c=IN IP4 0.0.0.0\r\n' +
'a=rtcp:9 IN IP4 0.0.0.0\r\n' +
'a=ice-ufrag:wkaf\r\n' +
'a=ice-pwd:2PI01Rh/wf4JKpfM0pr6LJ+d\r\n' +
'a=ice-options:trickle\r\n' +
'a=fingerprint:sha-256 86:BC:0B:F2:AB:2F:A2:A0:7F:FC:5B:5E:16:B8:61:62:E6:E6:18:FF:B6:85:6C:F0:DD:65:01:72:C1:16:88:E8\r\n' +
'a=setup:actpass\r\n' +
'a=mid:0\r\n' +
'a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level\r\n' +
'a=extmap:2 http://www.webrtc.org/experiments/rtp-hdrext/abs-send-time\r\n' +
'a=extmap:3 http://www.ietf.org/id/draft-holmer-rmcat-transport-wide-cc-extensions-01\r\n' +
'a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:mid\r\n' +
'a=extmap:5 urn:ietf:params:rtp-hdrext:sdes:rtp-stream-id\r\n' +
'a=extmap:6 urn:ietf:params:rtp-hdrext:sdes:repaired-rtp-stream-id\r\n' +
'a=sendrecv\r\n' +
'a=msid:VLvw0Ec4NwiXKVzTZyzl1m5aSLGW9EPe50Mz cd1c92ae-7d05-4ee8-9e21-3e2993c1c254\r\n' +
'a=rtcp-mux\r\n' +
'a=rtpmap:111 opus/48000/2\r\n' +
'a=rtcp-fb:111 transport-cc\r\n' +
'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' +
'a=ssrc:3060416220 cname:C9N45apy7vfT4Waq\r\n' +
'a=ssrc:3060416220 msid:VLvw0Ec4NwiXKVzTZyzl1m5aSLGW9EPe50Mz cd1c92ae-7d05-4ee8-9e21-3e2993c1c254\r\n' +
'a=ssrc:3060416220 mslabel:VLvw0Ec4NwiXKVzTZyzl1m5aSLGW9EPe50Mz\r\n' +
'a=ssrc:3060416220 label:cd1c92ae-7d05-4ee8-9e21-3e2993c1c254\r\n' +
'm=video 9 UDP/TLS/RTP/SAVPF 96 97 98 99 100 101 102 121 127 120 125 107 108 109 124 119 123 118 114 115 116\r\n' +
'c=IN IP4 0.0.0.0\r\n' +
'a=rtcp:9 IN IP4 0.0.0.0\r\n' +
'a=ice-ufrag:wkaf\r\n' +
'a=ice-pwd:2PI01Rh/wf4JKpfM0pr6LJ+d\r\n' +
'a=ice-options:trickle\r\n' +
'a=fingerprint:sha-256 86:BC:0B:F2:AB:2F:A2:A0:7F:FC:5B:5E:16:B8:61:62:E6:E6:18:FF:B6:85:6C:F0:DD:65:01:72:C1:16:88:E8\r\n' +
'a=setup:actpass\r\n' +
'a=mid:1\r\n' +
'a=extmap:14 urn:ietf:params:rtp-hdrext:toffset\r\n' +
'a=extmap:2 http://www.webrtc.org/experiments/rtp-hdrext/abs-send-time\r\n' +
'a=extmap:13 urn:3gpp:video-orientation\r\n' +
'a=extmap:3 http://www.ietf.org/id/draft-holmer-rmcat-transport-wide-cc-extensions-01\r\n' +
'a=extmap:12 http://www.webrtc.org/experiments/rtp-hdrext/playout-delay\r\n' +
'a=extmap:11 http://www.webrtc.org/experiments/rtp-hdrext/video-content-type\r\n' +
'a=extmap:7 http://www.webrtc.org/experiments/rtp-hdrext/video-timing\r\n' +
'a=extmap:8 http://www.webrtc.org/experiments/rtp-hdrext/color-space\r\n' +
'a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:mid\r\n' +
'a=extmap:5 urn:ietf:params:rtp-hdrext:sdes:rtp-stream-id\r\n' +
'a=extmap:6 urn:ietf:params:rtp-hdrext:sdes:repaired-rtp-stream-id\r\n' +
'a=sendrecv\r\n' +
'a=msid:VLvw0Ec4NwiXKVzTZyzl1m5aSLGW9EPe50Mz 95173d41-de5c-4864-8745-a8573f23f3d8\r\n' +
'a=rtcp-mux\r\n' +
'a=rtcp-rsize\r\n' +
'a=rtpmap:102 H264/90000\r\n' +
'a=rtcp-fb:102 goog-remb\r\n' +
'a=rtcp-fb:102 transport-cc\r\n' +
'a=rtcp-fb:102 ccm fir\r\n' +
'a=rtcp-fb:102 nack\r\n' +
'a=rtcp-fb:102 nack pli\r\n' +
'a=fmtp:102 level-asymmetry-allowed=1;packetization-mode=1;profile-level-id=42001f\r\n' +
'a=rtpmap:121 rtx/90000\r\n' +
'a=fmtp:121 apt=102\r\n' +
'a=rtpmap:127 H264/90000\r\n' +
'a=rtcp-fb:127 goog-remb\r\n' +
'a=rtcp-fb:127 transport-cc\r\n' +
'a=rtcp-fb:127 ccm fir\r\n' +
'a=rtcp-fb:127 nack\r\n' +
'a=rtcp-fb:127 nack pli\r\n' +
'a=fmtp:127 level-asymmetry-allowed=1;packetization-mode=0;profile-level-id=42001f\r\n' +
'a=rtpmap:120 rtx/90000\r\n' +
'a=fmtp:120 apt=127\r\n' +
'a=rtpmap:125 H264/90000\r\n' +
'a=rtcp-fb:125 goog-remb\r\n' +
'a=rtcp-fb:125 transport-cc\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=fmtp:125 level-asymmetry-allowed=1;packetization-mode=1;profile-level-id=42e01f\r\n' +
'a=rtpmap:107 rtx/90000\r\n' +
'a=fmtp:107 apt=125\r\n' +
'a=rtpmap:108 H264/90000\r\n' +
'a=rtcp-fb:108 goog-remb\r\n' +
'a=rtcp-fb:108 transport-cc\r\n' +
'a=rtcp-fb:108 ccm fir\r\n' +
'a=rtcp-fb:108 nack\r\n' +
'a=rtcp-fb:108 nack pli\r\n' +
'a=fmtp:108 level-asymmetry-allowed=1;packetization-mode=0;profile-level-id=42e01f\r\n' +
'a=rtpmap:109 rtx/90000\r\n' +
'a=fmtp:109 apt=108\r\n' +
'a=rtpmap:124 H264/90000\r\n' +
'a=rtcp-fb:124 goog-remb\r\n' +
'a=rtcp-fb:124 transport-cc\r\n' +
'a=rtcp-fb:124 ccm fir\r\n' +
'a=rtcp-fb:124 nack\r\n' +
'a=rtcp-fb:124 nack pli\r\n' +
'a=fmtp:124 level-asymmetry-allowed=1;packetization-mode=1;profile-level-id=4d0032\r\n' +
'a=rtpmap:119 rtx/90000\r\n' +
'a=fmtp:119 apt=124\r\n' +
'a=rtpmap:123 H264/90000\r\n' +
'a=rtcp-fb:123 goog-remb\r\n' +
'a=rtcp-fb:123 transport-cc\r\n' +
'a=rtcp-fb:123 ccm fir\r\n' +
'a=rtcp-fb:123 nack\r\n' +
'a=rtcp-fb:123 nack pli\r\n' +
'a=fmtp:123 level-asymmetry-allowed=1;packetization-mode=1;profile-level-id=640032\r\n' +
'a=rtpmap:118 rtx/90000\r\n' +
'a=fmtp:118 apt=123\r\n' +
'a=rtpmap:114 red/90000\r\n' +
'a=rtpmap:115 rtx/90000\r\n' +
'a=fmtp:115 apt=114\r\n' +
'a=rtpmap:116 ulpfec/90000\r\n' +
'a=ssrc-group:FID 3194951553 658670364\r\n' +
'a=ssrc:3194951553 cname:C9N45apy7vfT4Waq\r\n' +
'a=ssrc:3194951553 msid:VLvw0Ec4NwiXKVzTZyzl1m5aSLGW9EPe50Mz 95173d41-de5c-4864-8745-a8573f23f3d8\r\n' +
'a=ssrc:3194951553 mslabel:VLvw0Ec4NwiXKVzTZyzl1m5aSLGW9EPe50Mz\r\n' +
'a=ssrc:3194951553 label:95173d41-de5c-4864-8745-a8573f23f3d8\r\n' +
'a=ssrc:658670364 cname:C9N45apy7vfT4Waq\r\n' +
'a=ssrc:658670364 msid:VLvw0Ec4NwiXKVzTZyzl1m5aSLGW9EPe50Mz 95173d41-de5c-4864-8745-a8573f23f3d8\r\n' +
'a=ssrc:658670364 mslabel:VLvw0Ec4NwiXKVzTZyzl1m5aSLGW9EPe50Mz\r\n' +
'a=ssrc:658670364 label:95173d41-de5c-4864-8745-a8573f23f3d8\r\n'
}
- Answer SDP 消息
{
type: 'answer',
sdp: 'v=0\r\n' +
'o=- 6808421739235470893 2 IN IP4 127.0.0.1\r\n' +
's=-\r\n' +
't=0 0\r\n' +
'a=group:BUNDLE 0 1\r\n' +
'a=extmap-allow-mixed\r\n' +
'a=msid-semantic: WMS\r\n' +
'm=audio 9 UDP/TLS/RTP/SAVPF 111 103 104 9 0 8 106 105 13 110 112 113 126\r\n' +
'c=IN IP4 0.0.0.0\r\n' +
'a=rtcp:9 IN IP4 0.0.0.0\r\n' +
'a=ice-ufrag:8fbZ\r\n' +
'a=ice-pwd:r/ZnPQzn6uh8LIKW1gfaacu6\r\n' +
'a=ice-options:trickle\r\n' +
'a=fingerprint:sha-256 3A:5E:40:E4:BD:31:64:74:86:41:5A:62:1B:CA:0A:0A:4A:A4:0D:59:68:D5:47:15:B6:53:FE:BE:0F:3C:8D:D6\r\n' +
'a=setup:active\r\n' +
'a=mid:0\r\n' +
'a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level\r\n' +
'a=extmap:2 http://www.webrtc.org/experiments/rtp-hdrext/abs-send-time\r\n' +
'a=extmap:3 http://www.ietf.org/id/draft-holmer-rmcat-transport-wide-cc-extensions-01\r\n' +
'a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:mid\r\n' +
'a=extmap:5 urn:ietf:params:rtp-hdrext:sdes:rtp-stream-id\r\n' +
'a=extmap:6 urn:ietf:params:rtp-hdrext:sdes:repaired-rtp-stream-id\r\n' +
'a=recvonly\r\n' +
'a=rtcp-mux\r\n' +
'a=rtpmap:111 opus/48000/2\r\n' +
'a=rtcp-fb:111 transport-cc\r\n' +
'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' +
'm=video 9 UDP/TLS/RTP/SAVPF 102 121 127 120 125 107 108 109 124 119 123 118 114 115 116\r\n' +
'c=IN IP4 0.0.0.0\r\n' +
'a=rtcp:9 IN IP4 0.0.0.0\r\n' +
'a=ice-ufrag:8fbZ\r\n' +
'a=ice-pwd:r/ZnPQzn6uh8LIKW1gfaacu6\r\n' +
'a=ice-options:trickle\r\n' +
'a=fingerprint:sha-256 3A:5E:40:E4:BD:31:64:74:86:41:5A:62:1B:CA:0A:0A:4A:A4:0D:59:68:D5:47:15:B6:53:FE:BE:0F:3C:8D:D6\r\n' +
'a=setup:active\r\n' +
'a=mid:1\r\n' +
'a=extmap:14 urn:ietf:params:rtp-hdrext:toffset\r\n' +
'a=extmap:2 http://www.webrtc.org/experiments/rtp-hdrext/abs-send-time\r\n' +
'a=extmap:13 urn:3gpp:video-orientation\r\n' +
'a=extmap:3 http://www.ietf.org/id/draft-holmer-rmcat-transport-wide-cc-extensions-01\r\n' +
'a=extmap:12 http://www.webrtc.org/experiments/rtp-hdrext/playout-delay\r\n' +
'a=extmap:11 http://www.webrtc.org/experiments/rtp-hdrext/video-content-type\r\n' +
'a=extmap:7 http://www.webrtc.org/experiments/rtp-hdrext/video-timing\r\n' +
'a=extmap:8 http://www.webrtc.org/experiments/rtp-hdrext/color-space\r\n' +
'a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:mid\r\n' +
'a=extmap:5 urn:ietf:params:rtp-hdrext:sdes:rtp-stream-id\r\n' +
'a=extmap:6 urn:ietf:params:rtp-hdrext:sdes:repaired-rtp-stream-id\r\n' +
'a=recvonly\r\n' +
'a=rtcp-mux\r\n' +
'a=rtcp-rsize\r\n' +
'a=rtpmap:102 H264/90000\r\n' +
'a=rtcp-fb:102 goog-remb\r\n' +
'a=rtcp-fb:102 transport-cc\r\n' +
'a=rtcp-fb:102 ccm fir\r\n' +
'a=rtcp-fb:102 nack\r\n' +
'a=rtcp-fb:102 nack pli\r\n' +
'a=fmtp:102 level-asymmetry-allowed=1;packetization-mode=1;profile-level-id=42001f\r\n' +
'a=rtpmap:121 rtx/90000\r\n' +
'a=fmtp:121 apt=102\r\n' +
'a=rtpmap:127 H264/90000\r\n' +
'a=rtcp-fb:127 goog-remb\r\n' +
'a=rtcp-fb:127 transport-cc\r\n' +
'a=rtcp-fb:127 ccm fir\r\n' +
'a=rtcp-fb:127 nack\r\n' +
'a=rtcp-fb:127 nack pli\r\n' +
'a=fmtp:127 level-asymmetry-allowed=1;packetization-mode=0;profile-level-id=42001f\r\n' +
'a=rtpmap:120 rtx/90000\r\n' +
'a=fmtp:120 apt=127\r\n' +
'a=rtpmap:125 H264/90000\r\n' +
'a=rtcp-fb:125 goog-remb\r\n' +
'a=rtcp-fb:125 transport-cc\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=fmtp:125 level-asymmetry-allowed=1;packetization-mode=1;profile-level-id=42e01f\r\n' +
'a=rtpmap:107 rtx/90000\r\n' +
'a=fmtp:107 apt=125\r\n' +
'a=rtpmap:108 H264/90000\r\n' +
'a=rtcp-fb:108 goog-remb\r\n' +
'a=rtcp-fb:108 transport-cc\r\n' +
'a=rtcp-fb:108 ccm fir\r\n' +
'a=rtcp-fb:108 nack\r\n' +
'a=rtcp-fb:108 nack pli\r\n' +
'a=fmtp:108 level-asymmetry-allowed=1;packetization-mode=0;profile-level-id=42e01f\r\n' +
'a=rtpmap:109 rtx/90000\r\n' +
'a=fmtp:109 apt=108\r\n' +
'a=rtpmap:124 H264/90000\r\n' +
'a=rtcp-fb:124 goog-remb\r\n' +
'a=rtcp-fb:124 transport-cc\r\n' +
'a=rtcp-fb:124 ccm fir\r\n' +
'a=rtcp-fb:124 nack\r\n' +
'a=rtcp-fb:124 nack pli\r\n' +
'a=fmtp:124 level-asymmetry-allowed=1;packetization-mode=1;profile-level-id=4d0015\r\n' +
'a=rtpmap:119 rtx/90000\r\n' +
'a=fmtp:119 apt=124\r\n' +
'a=rtpmap:123 H264/90000\r\n' +
'a=rtcp-fb:123 goog-remb\r\n' +
'a=rtcp-fb:123 transport-cc\r\n' +
'a=rtcp-fb:123 ccm fir\r\n' +
'a=rtcp-fb:123 nack\r\n' +
'a=rtcp-fb:123 nack pli\r\n' +
'a=fmtp:123 level-asymmetry-allowed=1;packetization-mode=1;profile-level-id=640015\r\n' +
'a=rtpmap:118 rtx/90000\r\n' +
'a=fmtp:118 apt=123\r\n' +
'a=rtpmap:114 red/90000\r\n' +
'a=rtpmap:115 rtx/90000\r\n' +
'a=fmtp:115 apt=114\r\n' +
'a=rtpmap:116 ulpfec/90000\r\n'
}
Wireshark 抓包
1.首先安装wireshark软件，这个地球人都知道
2.用wireshark抓取H264视频码流，最好过滤掉其他码流
3.右键点击H264的udp包，选择"Decode as..."，再选择Transport中的rtp选项，就解析成rtp包了
4.查看rtp包的payload type，比如说type是 102，那么在wireshark工具栏选择Edit->preferences->protocols->H264, 把H264 dynamic payload types设成 102
- RTP 流
-
RTP 包
-
H.264 荷载
- SPS
- FU-A
