diff --git a/apps/media-worker/src/produce.ts b/apps/media-worker/src/produce.ts
index 94ab253..e60a443 100644
--- a/apps/media-worker/src/produce.ts
+++ b/apps/media-worker/src/produce.ts
@@ -12,7 +12,7 @@
  * Everything else is env parity with the API's storage (S3_ENDPOINT/S3_ACCESS_KEY/
  * S3_SECRET_KEY/S3_BUCKET/S3_KEK) and DATABASE_URL for the job tables.
  */
-import { mkdirSync } from "node:fs";
+import { appendFileSync, mkdirSync } from "node:fs";
 import pino from "pino";
 import { Pool as PgPool } from "pg";
 import { laneFromEnv, resolveProduceFont } from "./env";
@@ -34,7 +34,15 @@ export async function startProduceWorker(): Promise<{ runner: ProduceRunner; poo
     fontFile,
     scratchRoot,
     lane,
-    redactor: { redact: () => "[produce stderr redacted]" },
+    redactor: {
+      redact: (line) => {
+        if (process.env.MEDIA_DEBUG_STDERR === "1") {
+          appendFileSync("/tmp/ffmpeg-debug.log", line + "\n");
+          return line;
+        }
+        return "[produce stderr redacted]";
+      },
+    },
     onStderr: (message) => logger.warn({ message }, "ffmpeg stderr"),
     onEvent: (event) => {
       switch (event.type) {