rendercheck

The worst bugs in generated media don't throw.

If your build renders speech or video — Remotion, an ffmpeg pipeline, a TTS step, an AI video API — your tests catch the exception that never happens. They do not catch narration at 300 words per minute, a voice track 18 dB under the footage, a clip that came back silent, or audio that stops mid-sentence while the API reports success.

npx rendercheck demo                  # see it fire, no files of your own needed
npx rendercheck check out/            # then point it at your renders

Exit code is 1 if anything failed or if nothing could be measured, 2 for a path that isn't there. It drops straight into CI.

// in a render script
import { execFileSync } from "node:child_process";

execFileSync("npx", ["rendercheck", "check", "out/lesson-1.mp4", "--strict"], {
  stdio: "inherit",
});

Requirements

This package is a thin wrapper around the Python CLI, which is where the checks live. It finds rendercheck, uvx, or pipx on your PATH:

pipx install rendercheck        # or: uv tool install rendercheck
brew install ffmpeg             # the measurements are ffmpeg's

Full documentation, the check reference, and the reasoning behind each default: https://github.com/rogermsc/rendercheck