1. 为什么需要WebRTC与SRS的组合在移动直播、在线教育、视频会议等实时互动场景中WebRTC技术已经成为行业标配。它最大的优势在于点对点低延迟传输实测端到端延迟可以控制在200ms以内。但纯P2P方案存在NAT穿透成功率问题这时候就需要像SRS这样的媒体服务器作为中继。我在实际项目中发现安卓端直接使用WebRTC原生API会有几个痛点信令服务器搭建复杂ICE候选地址收集不完整跨运营商传输质量不稳定SRS服务器恰好能解决这些问题内置完整的WebRTC信令处理自动生成TURN中继候选支持RTMP/WebRTC协议转换2. 环境准备从零搭建SRS服务2.1 服务器基础配置推荐使用Ubuntu 20.04 LTS系统实测对WebRTC支持最稳定。先安装基础依赖sudo apt update sudo apt install -y git g make python3 unzip编译安装SRS最新版当前稳定版为4.0git clone -b 4.0release https://github.com/ossrs/srs.git cd srs/trunk ./configure --with-ssl --with-hls --with-ffmpeg --with-http-callback make -j$(nproc)关键编译参数说明--with-ssl启用HTTPS支持--with-ffmpeg允许转码--with-http-callback支持事件通知2.2 HTTPS证书申请实战WebRTC强制要求安全上下文这意味着你必须配置HTTPS。我推荐使用Lets Encrypt免费证书sudo apt install certbot sudo certbot certonly --standalone -d yourdomain.com获取到的证书会存放在/etc/letsencrypt/live/yourdomain.com/目录包含fullchain.pem证书链privkey.pem私钥注意证书自动续期需要配置crontab0 3 * * * certbot renew --quiet --post-hook systemctl reload nginx3. SRS关键配置详解3.1 RTC服务器配置修改conf/rtc.conf配置文件rtc_server { enabled on; listen 8000; candidate $YOUR_SERVER_IP; } http_server { https { enabled on; listen 8088; key /etc/letsencrypt/live/yourdomain.com/privkey.pem; cert /etc/letsencrypt/live/yourdomain.com/fullchain.pem; } }启动时指定配置文件./objs/srs -c conf/rtc.conf3.2 安卓端必须的ICE配置在安卓应用中需要配置ICE服务器PeerConnection.IceServer stunServer PeerConnection.IceServer.builder(stun:yourdomain.com:3478) .createIceServer(); PeerConnection.IceServer turnServer PeerConnection.IceServer.builder(turn:yourdomain.com:3478) .setUsername(your_username) .setPassword(your_password) .createIceServer();4. 安卓端推流实战4.1 相机采集实现使用Camera2 API获取视频流private void startCamera() { CameraManager manager (CameraManager) getSystemService(CAMERA_SERVICE); String cameraId manager.getCameraIdList()[0]; manager.openCamera(cameraId, new CameraDevice.StateCallback() { Override public void onOpened(NonNull CameraDevice camera) { // 创建CaptureSession ListSurface surfaces new ArrayList(); surfaces.add(peerConnectionFactory.createVideoSurface(textureView)); surfaces.add(imageReader.getSurface()); camera.createCaptureSession(surfaces, new CameraCaptureSession.StateCallback() { // 处理帧数据 }, null); } }, null); }4.2 编码参数优化针对移动端建议的编码参数VideoEncoderFactory encoderFactory new DefaultVideoEncoderFactory( rootEglBase.getEglBaseContext(), true, // 启用Intel VP8编码器 true // 启用H264硬件编码 ); MediaConstraints videoConstraints new MediaConstraints(); videoConstraints.mandatory.add(new MediaConstraints.KeyValuePair( scaleResolutionDownBy, 1.5 // 降低分辨率减轻负载 ));5. 常见问题排查指南5.1 连接失败排查步骤检查ICE状态peerConnection.setIceConnectionObserver(new IceConnectionObserver() { Override public void onIceConnectionChange(PeerConnection.IceConnectionState state) { Log.d(TAG, ICE状态变化: state); } });验证TURN服务器turnutils_uclient -t -u username -w password yourdomain.com抓包分析tcpdump -i any -w webrtc.pcap port 8000 or port 34785.2 延迟优化技巧设置更激进的NACK策略RtpTransceiver.RtpTransceiverInit init new RtpTransceiver.RtpTransceiverInit(); init.setDirection(RtpTransceiver.RtpTransceiverDirection.SEND_RECEIVE); init.setStreamIds(Collections.singletonList(stream1)); // 关键配置 init.setSendCodecPreferences(Arrays.asList( VideoCodecInfo.VP9, VideoCodecInfo.H264 ));调整Jitter BufferPeerConnectionFactory.Options options new PeerConnectionFactory.Options(); options.networkIgnoreMask 0; options.disableEncryption false; options.disableNetworkMonitor false;6. 进阶云端录制与回放6.1 录制配置在SRS配置中添加vhost __defaultVhost__ { dvr { enabled on; dvr_path /data/recordings/[app]/[stream]/[timestamp].mp4; dvr_plan segment; dvr_duration 3600; // 每1小时分段 } }6.2 安卓播放器集成使用ExoPlayer播放录制内容DataSource.Factory dataSourceFactory new DefaultDataSourceFactory( this, Util.getUserAgent(this, WebRTCDemo)); ProgressiveMediaSource mediaSource new ProgressiveMediaSource.Factory(dataSourceFactory) .createMediaSource(Uri.parse(https://yourdomain.com/recordings/livestream.mp4)); player.prepare(mediaSource); player.setPlayWhenReady(true);7. 性能监控方案7.1 SRS状态获取通过HTTP API获取服务器状态curl http://localhost:1985/api/v1/versions返回示例{ code: 0, data: { uptime: 86400, connections: 42, bitrate: 3800000 } }7.2 安卓端质量统计获取实时传输数据peerConnection.getStats(new StatsObserver() { Override public void onComplete(StatsReport[] reports) { for (StatsReport report : reports) { if (report.type.equals(ssrc)) { Log.d(STATS, 丢包率: report.values.get(packetsLost)); } } } });在实际项目中这套方案已经支撑过500并发连接的在线教育场景。关键是要做好以下几点定期检查证书有效期监控服务器ICE候选地址有效性安卓端做好弱网适配测试