Initial commit

lib/video/duration.ts

@@ -0,0 +1,59 @@
+import "server-only";
+import { spawn } from "node:child_process";
+
+const cache = new Map<string, number>();
+
+const PROBE_TIMEOUT_MS = 10_000;
+
+/**
+ * Probe a video file's duration in seconds via ffprobe. Cached per-path
+ * for the lifetime of the process — files don't change duration on us.
+ * Returns null if ffprobe fails or returns garbage.
+ *
+ * Caps the probe at PROBE_TIMEOUT_MS and ties to an optional AbortSignal
+ * so a hung ffprobe (network mount, weird codec, dead disk) can't leave
+ * the request awaiting forever or zombie the subprocess.
+ */
+export async function probeDuration(abs: string, signal?: AbortSignal): Promise<number | null> {
+  const cached = cache.get(abs);
+  if (cached !== undefined) return cached;
+  return new Promise((resolve) => {
+    const proc = spawn("ffprobe", [
+      "-v", "error",
+      "-show_entries", "format=duration",
+      "-of", "default=noprint_wrappers=1:nokey=1",
+      abs,
+    ]);
+    let out = "";
+    let settled = false;
+
+    const settle = (n: number | null) => {
+      if (settled) return;
+      settled = true;
+      if (timeoutId) clearTimeout(timeoutId);
+      if (signal && abortHandler) signal.removeEventListener("abort", abortHandler);
+      if (n != null && Number.isFinite(n) && n > 0) {
+        cache.set(abs, n);
+        resolve(n);
+      } else {
+        resolve(null);
+      }
+    };
+
+    const kill = () => {
+      try { proc.kill("SIGKILL"); } catch { /* ignore */ }
+      settle(null);
+    };
+
+    const timeoutId = setTimeout(kill, PROBE_TIMEOUT_MS);
+    const abortHandler = signal ? () => kill() : null;
+    if (signal && abortHandler) {
+      if (signal.aborted) { kill(); return; }
+      signal.addEventListener("abort", abortHandler, { once: true });
+    }
+
+    proc.stdout?.on("data", (d) => { out += d.toString(); });
+    proc.on("close", () => settle(Number(out.trim())));
+    proc.on("error", () => settle(null));
+  });
+}