homebridge-examples/bridged-camera-example-typescript/src/streamingDelegate.ts

import ip from "ip";
import {ChildProcess, spawn} from "child_process";
import {
  CameraController,
  CameraStreamingDelegate, HAP,
  PrepareStreamCallback,
  PrepareStreamRequest,
  PrepareStreamResponse,
  SnapshotRequest,
  SnapshotRequestCallback,
  SRTPCryptoSuites,
  StreamingRequest,
  StreamRequestCallback,
  StreamRequestTypes,
  StreamSessionIdentifier,
  VideoInfo
} from "homebridge";

type SessionInfo = {
  address: string, // address of the HAP controller

  videoPort: number,
  videoCryptoSuite: SRTPCryptoSuites, // should be saved if multiple suites are supported
  videoSRTP: Buffer, // key and salt concatenated
  videoSSRC: number, // rtp synchronisation source

  /* Won't be save as audio is not supported by this example
  audioPort: number,
  audioCryptoSuite: SRTPCryptoSuites,
  audioSRTP: Buffer,
  audioSSRC: number,
   */
}

const FFMPEGH264ProfileNames = [
  "baseline",
  "main",
  "high"
];
const FFMPEGH264LevelNames = [
  "3.1",
  "3.2",
  "4.0"
];

export class ExampleFFMPEGStreamingDelegate implements CameraStreamingDelegate {

  private ffmpegDebugOutput: boolean = false;

  private readonly hap: HAP;
  controller?: CameraController;

  // keep track of sessions
  pendingSessions: Record<string, SessionInfo> = {};
  ongoingSessions: Record<string, ChildProcess> = {};

  constructor(hap: HAP) {
    this.hap = hap;
  }

  handleSnapshotRequest(request: SnapshotRequest, callback: SnapshotRequestCallback): void {
    const ffmpegCommand = `-f lavfi -i testsrc=s=${request.width}x${request.height} -vframes 1 -f mjpeg -`;
    const ffmpeg = spawn("ffmpeg", ffmpegCommand.split(" "), {env: process.env});

    const snapshotBuffers: Buffer[] = [];

    ffmpeg.stdout.on('data', data => snapshotBuffers.push(data));
    ffmpeg.stderr.on('data', data => {
      if (this.ffmpegDebugOutput) {
        console.log("SNAPSHOT: " + String(data));
      }
    });

    ffmpeg.on('exit', (code, signal) => {
      if (signal) {
        console.log("Snapshot process was killed with signal: " + signal);
        callback(new Error("killed with signal " + signal));
      } else if (code === 0) {
        console.log(`Successfully captured snapshot at ${request.width}x${request.height}`);
        callback(undefined, Buffer.concat(snapshotBuffers));
      } else {
        console.log("Snapshot process exited with code " + code);
        callback(new Error("Snapshot process exited with code " + code));
      }
    });
  }

  // called when iOS request rtp setup
  prepareStream(request: PrepareStreamRequest, callback: PrepareStreamCallback): void {
    const sessionId: StreamSessionIdentifier = request.sessionID;
    const targetAddress = request.targetAddress;

    const video = request.video;
    const videoPort = video.port;

    const videoCryptoSuite = video.srtpCryptoSuite; // could be used to support multiple crypto suite (or support no suite for debugging)
    const videoSrtpKey = video.srtp_key;
    const videoSrtpSalt = video.srtp_salt;

    const videoSSRC = this.hap.CameraController.generateSynchronisationSource();

    const sessionInfo: SessionInfo = {
      address: targetAddress,

      videoPort: videoPort,
      videoCryptoSuite: videoCryptoSuite,
      videoSRTP: Buffer.concat([videoSrtpKey, videoSrtpSalt]),
      videoSSRC: videoSSRC,
    };

    const currentAddress = ip.address("public", request.addressVersion); // ipAddress version must match
    const response: PrepareStreamResponse = {
      address: currentAddress,
      video: {
        port: videoPort,
        ssrc: videoSSRC,

        srtp_key: videoSrtpKey,
        srtp_salt: videoSrtpSalt,
      },
      // audio is omitted as we do not support audio in this example
    };

    this.pendingSessions[sessionId] = sessionInfo;
    callback(undefined, response);
  }

  // called when iOS device asks stream to start/stop/reconfigure
  handleStreamRequest(request: StreamingRequest, callback: StreamRequestCallback): void {
    const sessionId = request.sessionID;

    switch (request.type) {
      case this.hap.StreamRequestTypes.START:
        const sessionInfo = this.pendingSessions[sessionId];

        const video: VideoInfo = request.video;

        const profile = FFMPEGH264ProfileNames[video.profile];
        const level = FFMPEGH264LevelNames[video.level];
        const width = video.width;
        const height = video.height;
        const fps = video.fps;

        const payloadType = video.pt;
        const maxBitrate = video.max_bit_rate;
        const rtcpInterval = video.rtcp_interval; // usually 0.5
        const mtu = video.mtu; // maximum transmission unit

        const address = sessionInfo.address;
        const videoPort = sessionInfo.videoPort;
        const ssrc = sessionInfo.videoSSRC;
        const cryptoSuite = sessionInfo.videoCryptoSuite;
        const videoSRTP = sessionInfo.videoSRTP.toString("base64");

        console.log(`Starting video stream (${width}x${height}, ${fps} fps, ${maxBitrate} kbps, ${mtu} mtu)...`);

        let videoffmpegCommand = `-f lavfi -i testsrc=size=${width}x${height}:rate=${fps} -map 0:0 ` +
          `-c:v libx264 -pix_fmt yuv420p -r ${fps} -an -sn -dn -b:v ${maxBitrate}k -bufsize ${2*maxBitrate}k -maxrate ${maxBitrate}k ` +
          `-payload_type ${payloadType} -ssrc ${ssrc} -f rtp `; // -profile:v ${profile} -level:v ${level}

        if (cryptoSuite !== this.hap.SRTPCryptoSuites.NONE) { // actually ffmpeg just supports AES_CM_128_HMAC_SHA1_80
          videoffmpegCommand += `-srtp_out_suite ${this.hap.SRTPCryptoSuites[cryptoSuite]} -srtp_out_params ${videoSRTP} s`;
        }

        videoffmpegCommand += `rtp://${address}:${videoPort}?rtcpport=${videoPort}&localrtcpport=${videoPort}&pkt_size=${mtu}`;

        if (this.ffmpegDebugOutput) {
          console.log("FFMPEG command: ffmpeg " + videoffmpegCommand);
        }

        const ffmpegVideo = spawn('ffmpeg', videoffmpegCommand.split(' '), {env: process.env});

        let started = false;
        ffmpegVideo.stderr.on('data', data => {
          if (!started) {
            started = true;
            console.log("FFMPEG: received first frame");

            callback(); // do not forget to execute callback once set up
          }

          if (this.ffmpegDebugOutput) {
            console.log("VIDEO: " + String(data));
          }
        });
        ffmpegVideo.on('error', error => {
          console.log("[Video] Failed to start video stream: " + error.message);
          callback(new Error("ffmpeg process creation failed!"));
        });
        ffmpegVideo.on('exit', (code, signal) => {
          const message = "[Video] ffmpeg exited with code: " + code + " and signal: " + signal;

          if (code == null || code === 255) {
            console.log(message + " (Video stream stopped!)");
          } else {
            console.log(message + " (error)");

            if (!started) {
              callback(new Error(message));
            } else {
              this.controller!.forceStopStreamingSession(sessionId);
            }
          }
        });

        this.ongoingSessions[sessionId] = ffmpegVideo;
        delete this.pendingSessions[sessionId];

        break;
      case this.hap.StreamRequestTypes.RECONFIGURE:
        // not supported by this example
        console.log("Received (unsupported) request to reconfigure to: " + JSON.stringify(request.video));
        callback();
        break;
      case this.hap.StreamRequestTypes.STOP:
        const ffmpegProcess = this.ongoingSessions[sessionId];

        try {
          if (ffmpegProcess) {
            ffmpegProcess.kill('SIGKILL');
          }
        } catch (e) {
          console.log("Error occurred terminating the video process!");
          console.log(e);
        }

        delete this.ongoingSessions[sessionId];

        console.log("Stopped streaming session!");
        callback();
        break;
    }
  }

}