pass 1

server/src/services/media/previewTranscoderService.js

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+const { spawn } = require('child_process');
+const EventEmitter = require('events');
+const logger = require('../../globals/logger').child('previewTranscoder');
+const { loadConfig } = require('../../helpers/configLoader');
+const roverManager = require('../roverManager');
+const { getRoomCameras, roomCameraEvents } = require('../roomCameraService');
+
+const events = new EventEmitter();
+const config = loadConfig();
+const mediaConfig = config.media || {};
+const previewConfig = mediaConfig.preview || {};
+
+const ENABLED = Boolean(previewConfig.enabled);
+const PREVIEW_CODEC = String(previewConfig.codec || 'av1').toLowerCase();
+const PREVIEW_FPS = Number(previewConfig.fps || 10);
+const PREVIEW_WIDTH = Number(previewConfig.width || 640);
+const ROOM_BITRATE_KBPS = Number(previewConfig.roomBitrateKbps || 200);
+const ROVER_BITRATE_KBPS = Number(previewConfig.roverBitrateKbps || 350);
+const PRESET = Number.isFinite(previewConfig.preset) ? String(previewConfig.preset) : '8';
+const GOP_SECONDS = Number(previewConfig.gopSeconds || 2);
+const FFMPEG_BIN = previewConfig.ffmpegBin || process.env.FFMPEG_BIN || 'ffmpeg';
+
+const recorders = new Map(); // key -> { proc, source }
+let syncTimer = null;
+
+function encodeStreamId(streamId) {
+  return encodeURIComponent(streamId).replace(/%2F/g, '/');
+}
+
+function buildSrtReadUrl(streamId) {
+  return `srt://127.0.0.1:9000?streamid=read:${encodeStreamId(streamId)}`;
+}
+
+function buildSrtPublishUrl(streamId) {
+  const encoded = encodeStreamId(streamId);
+  return `srt://127.0.0.1:9000?streamid=#!::r=${encoded},m=publish&latency=10&mode=caller&transtype=live&pkt_size=1316`;
+}
+
+function sanitizeCodec(codec) {
+  return String(codec || '').toLowerCase().replace(/[^a-z0-9]/g, '') || 'av1';
+}
+
+function buildPreviewId(id, codec) {
+  return `${id}-preview-${sanitizeCodec(codec)}`;
+}
+
+function getRoomCameraStream(camera) {
+  if (camera.streamUrl) return camera.streamUrl;
+  const url = String(camera.url || '');
+  if (url.includes('.mjpg') || url.includes('mjpeg') || url.includes('stream')) {
+    return url;
+  }
+  return null;
+}
+
+function listSources() {
+  const rooms = getRoomCameras()
+    .map((camera) => {
+      const streamUrl = getRoomCameraStream(camera);
+      if (!streamUrl) return null;
+      const id = String(camera.id);
+      return {
+        type: 'room',
+        id,
+        label: camera.name || id,
+        inputUrl: streamUrl,
+        outputId: `room/${buildPreviewId(id, PREVIEW_CODEC)}`,
+        bitrateKbps: ROOM_BITRATE_KBPS,
+      };
+    })
+    .filter(Boolean);
+  const rovers = roverManager.getRoster().map((rover) => {
+    const id = String(rover.id);
+    return {
+      type: 'rover',
+      id,
+      label: rover.name || id,
+      inputUrl: buildSrtReadUrl(id),
+      outputId: buildPreviewId(id, PREVIEW_CODEC),
+      bitrateKbps: ROVER_BITRATE_KBPS,
+    };
+  });
+  return [...rooms, ...rovers];
+}
+
+function buildKey(source) {
+  return `${source.type}:${source.id}:${source.outputId}`;
+}
+
+function buildArgs(source) {
+  const gop = Math.max(1, Math.round(GOP_SECONDS * PREVIEW_FPS));
+  const maxrate = Math.floor(source.bitrateKbps * 1.1);
+  const bufsize = Math.max(1, source.bitrateKbps * 2);
+  return [
+    '-hide_banner',
+    '-loglevel',
+    'info',
+    '-fflags',
+    'nobuffer',
+    '-flags',
+    'low_delay',
+    '-i',
+    source.inputUrl,
+    '-an',
+    '-vf',
+    `fps=${PREVIEW_FPS},scale=${PREVIEW_WIDTH}:-1`,
+    '-c:v',
+    PREVIEW_CODEC === 'av1' ? 'libsvtav1' : 'libx264',
+    '-preset',
+    PRESET,
+    '-g',
+    String(gop),
+    '-keyint_min',
+    String(gop),
+    '-b:v',
+    `${source.bitrateKbps}k`,
+    '-maxrate',
+    `${maxrate}k`,
+    '-bufsize',
+    `${bufsize}k`,
+    '-pix_fmt',
+    'yuv420p',
+    '-f',
+    'mpegts',
+    buildSrtPublishUrl(source.outputId),
+  ];
+}
+
+function spawnRecorder(source) {
+  const key = buildKey(source);
+  if (recorders.has(key)) return;
+  const args = buildArgs(source);
+  const proc = spawn(FFMPEG_BIN, args, { stdio: ['ignore', 'ignore', 'pipe'] });
+  const stderrChunks = [];
+  let stderrSize = 0;
+  proc.stderr.on('data', (chunk) => {
+    if (!chunk || stderrSize > 8192) return;
+    stderrChunks.push(chunk);
+    stderrSize += chunk.length;
+  });
+  recorders.set(key, { proc, source });
+  proc.on('exit', (code, signal) => {
+    recorders.delete(key);
+    const stderrBuffer = stderrChunks.length ? Buffer.concat(stderrChunks) : null;
+    if (stderrBuffer && stderrBuffer.length) {
+      const preview = stderrBuffer.toString('utf8', 0, 600).trim();
+      logger.warn('Preview transcoder stderr', {
+        key,
+        stderrBytes: stderrBuffer.length,
+        stderrPreview: preview || '<non-utf8>',
+      });
+    } else {
+      logger.warn('Preview transcoder stderr', { key, stderrBytes: 0 });
+    }
+    if (!ENABLED) return;
+    const delay = 2000;
+    logger.warn('Preview transcoder exited; restarting', { key, code, signal });
+    setTimeout(() => {
+      if (!recorders.has(key) && ENABLED) {
+        spawnRecorder(source);
+      }
+    }, delay);
+  });
+  events.emit('spawn', { key, source });
+}
+
+function stopRecorder(key) {
+  const entry = recorders.get(key);
+  if (!entry) return;
+  entry.proc.kill('SIGTERM');
+  recorders.delete(key);
+  events.emit('stop', { key, source: entry.source });
+}
+
+function syncRecorders() {
+  const sources = listSources();
+  const desiredKeys = new Set();
+  sources.forEach((source) => {
+    const key = buildKey(source);
+    desiredKeys.add(key);
+    if (!recorders.has(key)) {
+      spawnRecorder(source);
+    }
+  });
+  Array.from(recorders.keys()).forEach((key) => {
+    if (!desiredKeys.has(key)) {
+      stopRecorder(key);
+    }
+  });
+  logger.info('Preview transcoders synced', { total: desiredKeys.size });
+}
+
+function start() {
+  if (!ENABLED) {
+    logger.info('Preview transcoders disabled');
+    return;
+  }
+  syncRecorders();
+  if (!syncTimer) {
+    syncTimer = setInterval(syncRecorders, 10000);
+  }
+}
+
+function stop() {
+  if (syncTimer) {
+    clearInterval(syncTimer);
+    syncTimer = null;
+  }
+  Array.from(recorders.keys()).forEach((key) => stopRecorder(key));
+}
+
+roverManager.managerEvents.on('rover', () => {
+  if (ENABLED) {
+    syncRecorders();
+  }
+});
+roomCameraEvents.on('update', () => {
+  if (ENABLED) {
+    syncRecorders();
+  }
+});
+
+start();
+
+module.exports = {
+  previewEvents: events,
+  syncPreviewTranscoders: syncRecorders,
+  stopPreviewTranscoders: stop,
+};