Keep pause across Coolify restarts, apply the chosen still from the image picker, and remux clips with Range/faststart so finished video can be scrubbed.

Co-authored-by: Cursor <cursoragent@cursor.com>

server/utils/ffmpeg.ts

@@ -1,4 +1,4 @@
-import { existsSync, writeFileSync, readFileSync, unlinkSync } from 'node:fs'
+import { existsSync, writeFileSync, readFileSync, unlinkSync, statSync, openSync, readSync, closeSync, copyFileSync } from 'node:fs'
 import { dirname, join } from 'node:path'
 import { spawn } from 'node:child_process'
 
@@ -171,6 +171,58 @@ async function probeSize(filePath: string) {
   }
 }
 
+function mp4MoovIsAtStart(filePath: string) {
+  const fd = openSync(filePath, 'r')
+  try {
+    let offset = 0
+    const header = Buffer.alloc(16)
+    for (let i = 0; i < 12; i++) {
+      if (readSync(fd, header, 0, 8, offset) < 8) return false
+      let size = header.readUInt32BE(0)
+      const type = header.toString('ascii', 4, 8)
+      if (size === 1) {
+        if (readSync(fd, header, 8, 8, offset + 8) < 8) return false
+        size = Number(header.readBigUInt64BE(8))
+      }
+      if (!size || size < 8) return false
+      if (type === 'moov') return true
+      if (type === 'mdat') return false
+      offset += size
+    }
+    return false
+  } finally {
+    closeSync(fd)
+  }
+}
+
+export async function remuxFaststart(inputPath: string) {
+  if (!existsSync(inputPath)) return
+  try {
+    if (mp4MoovIsAtStart(inputPath)) return
+  } catch {
+    // Fall through and try a remux anyway.
+  }
+  const tmp = `${inputPath}.faststart.tmp.mp4`
+  try {
+    await runFfmpeg([
+      '-y',
+      '-i', inputPath,
+      '-c', 'copy',
+      '-map', '0',
+      '-movflags', '+faststart',
+      tmp
+    ], 120000)
+    if (!existsSync(tmp) || statSync(tmp).size < 32) {
+      try { unlinkSync(tmp) } catch { /* ignore */ }
+      return
+    }
+    copyFileSync(tmp, inputPath)
+    try { unlinkSync(tmp) } catch { /* ignore */ }
+  } catch {
+    try { unlinkSync(tmp) } catch { /* ignore */ }
+  }
+}
+
 function encodeArgs(outputPath: string, withAudio: boolean) {
   const args = [
     '-c:v', 'libx264',
@@ -271,7 +323,7 @@ export async function concatMp4(part1Path: string, part2Path: string, outputPath
   const listPath = join(dirname(outputPath), 'concat_list.txt')
   writeFileSync(listPath, `file '${concatPath(part1Path)}'\nfile '${concatPath(part2Path)}'\n`)
   try {
-    await runFfmpeg(['-y', '-f', 'concat', '-safe', '0', '-i', listPath, '-c', 'copy', outputPath], 180000)
+    await runFfmpeg(['-y', '-f', 'concat', '-safe', '0', '-i', listPath, '-c', 'copy', '-movflags', '+faststart', outputPath], 180000)
     await assertStitchLength(part1Path, part2Path, outputPath)
   } catch {
     await concatReencode(part1Path, part2Path, outputPath)