From eda0ae6b1d88664392a85e1446511f9528c014e3 Mon Sep 17 00:00:00 2001
From: Joao Carreira <jfmcarreira@gmail.com>
Date: Mon, 28 Sep 2026 10:48:47 +0100
Subject: [PATCH] feat: compression 17

---
 src/helpers/ffmpeg-log.server.ts              | 129 ++++++++++++++++++
 src/pages/api/assets/compression/transcode.ts |   4 +-
 2 files changed, 132 insertions(+), 1 deletion(-)
 create mode 100644 src/helpers/ffmpeg-log.server.ts

diff --git a/src/helpers/ffmpeg-log.server.ts b/src/helpers/ffmpeg-log.server.ts
new file mode 100644
index 0000000..599b09a
--- /dev/null
+++ b/src/helpers/ffmpeg-log.server.ts
@@ -0,0 +1,129 @@
+import { createWriteStream } from "node:fs";
+import { spawn } from "node:child_process";
+import path from "node:path";
+
+const STDERR_TAIL_BYTES = 64 * 1024;
+
+const tokenizeCommand = (input: string): string[] => {
+  const args: string[] = [];
+  let current = "";
+  let quote: "'" | '"' | null = null;
+  let escaping = false;
+  let tokenStarted = false;
+
+  for (const char of input) {
+    if (escaping) {
+      current += char;
+      escaping = false;
+      tokenStarted = true;
+      continue;
+    }
+
+    if (char === "\\" && quote !== "'") {
+      escaping = true;
+      tokenStarted = true;
+      continue;
+    }
+
+    if (quote) {
+      if (char === quote) {
+        quote = null;
+      } else {
+        current += char;
+      }
+      tokenStarted = true;
+      continue;
+    }
+
+    if (char === "'" || char === '"') {
+      quote = char;
+      tokenStarted = true;
+      continue;
+    }
+
+    if (/\s/.test(char)) {
+      if (tokenStarted) {
+        args.push(current);
+        current = "";
+        tokenStarted = false;
+      }
+      continue;
+    }
+
+    current += char;
+    tokenStarted = true;
+  }
+
+  if (escaping) throw new Error("FFmpeg command ends with an incomplete escape sequence");
+  if (quote) throw new Error("FFmpeg command contains an unterminated quote");
+  if (tokenStarted) args.push(current);
+
+  return args;
+};
+
+const getLogPath = (outputPath: string) => {
+  const parsed = path.parse(outputPath);
+  return path.join(parsed.dir, `${parsed.name}.log`);
+};
+
+const formatArgument = (value: string) =>
+  /\s/.test(value) ? JSON.stringify(value) : value;
+
+export const runLoggedFfmpegCommand = async (
+  command: string,
+  inputPath: string,
+  outputPath: string
+) => {
+  const tokens = tokenizeCommand(command);
+  if (tokens.length === 0) throw new Error("FFmpeg command is empty");
+
+  const resolved = tokens.map((token) => token
+    .split("{input}").join(inputPath)
+    .split("{output}").join(outputPath));
+
+  // Support both "ffmpeg -i ..." and argument-only settings such as "-i ...".
+  const commandIncludesExecutable = !resolved[0]?.startsWith("-");
+  const executable = commandIncludesExecutable ? resolved[0] : "ffmpeg";
+  const args = commandIncludesExecutable ? resolved.slice(1) : resolved;
+  const logPath = getLogPath(outputPath);
+  const log = createWriteStream(logPath, { flags: "w" });
+
+  log.write(`Command: ${[executable, ...args].map(formatArgument).join(" ")}\n\n`);
+
+  await new Promise<void>((resolve, reject) => {
+    const child = spawn(executable, args, { shell: false });
+    let stderrTail = "";
+    let settled = false;
+
+    child.stdout.on("data", (chunk: Buffer) => {
+      log.write(chunk);
+    });
+
+    child.stderr.on("data", (chunk: Buffer) => {
+      log.write(chunk);
+      stderrTail = (stderrTail + chunk.toString()).slice(-STDERR_TAIL_BYTES);
+    });
+
+    const finish = (error?: Error) => {
+      if (settled) return;
+      settled = true;
+      log.end(() => error ? reject(error) : resolve());
+    };
+
+    child.on("error", (error) => {
+      log.write(`\n\nFailed to start FFmpeg: ${error.message}\n`);
+      finish(error);
+    });
+
+    child.on("close", (code, signal) => {
+      if (settled) return;
+
+      log.write(
+        `\n\nFFmpeg exited with code ${code ?? "unknown"}${signal ? ` (${signal})` : ""}\n`
+      );
+
+      if (code === 0) {
+        finish();
+        return;
+      }
+
diff --git a/src/pages/api/assets/compression/transcode.ts b/src/pages/api/assets/compression/transcode.ts
index 4c523c7..6ed8cab 100644
--- a/src/pages/api/assets/compression/transcode.ts
+++ b/src/pages/api/assets/compression/transcode.ts
@@ -45,7 +45,9 @@ export default async function handler(req: NextApiRequest, res: NextApiResponse)
 
     const originalStat = await stat(inputPath);
     const command = await getFfmpegCommand(currentUser.id);
-    await runFfmpegCommand(command, inputPath, outputPath);
+    const runLoggedFfmpegCommand: typeof runFfmpegCommand =
+      (await import("@/helpers/ffmpeg-log.server")).runLoggedFfmpegCommand;
+    await runLoggedFfmpegCommand(command, inputPath, outputPath);
     const outputStat = await stat(outputPath);
     const outputFileName = outputPath.split("/").pop() || `${asset.id}-compressed.mp4`;