batch relay sound to video

Replace the audio on your video files. Drag in video and audio, Laybacker auto-matches the pairs, checks and fixes sound levels, and exports. Built for sound post-production.

Mac · Apple Silicon M1 / M2 / M3 / M4 · .pkg installer Mac · Intel x86_64 · .pkg installer Windows x64 · installer (.exe)

latest release · all versions & release notes

As featured on Production Expert “These Audio Pros Built Their Own Plugins With AI — Here's Why” Read the article →
Laybacker app — dark mode Dark mode

👆 Click the screenshot to see light mode

What it does

▸ Drag, drop, done

Drop video and audio together — Laybacker matches them by duration and name, and lets you fix any pairing by hand.

▸ Broadcast-spec loudness

Normalise to LUFS targets (EBU R128 −23, streaming −16, ATSC A/85) or full-scale peak, measured to ITU-R BS.1770-4.

▸ 6-frame silence check

Verify and fix head/tail silence for UK commercial broadcast delivery, with clean fades to avoid clicks.

▸ Smart export

Keep the original streams or re-encode to H.264 / AAC. Smart filenames with optional date stamps.

▸ FFmpeg included

No separate install — a pinned, bundled FFmpeg ships inside the app. Nothing else to set up.

▸ Fully local & private

Every file is processed on your own machine. Nothing is ever uploaded.

First launch

First launch? Laybacker is free and open-source. To keep costs low, it's not part of the Apple Developer Scheme, so opening it the first time takes a couple of extra clicks. This is totally standard, and you only have to do it once. To reassure you it's malware and virus free, each download is checked independently by VirusTotal.
Mac:
  1. Double-click the downloaded .pkg.
  2. If you see “Apple could not verify…”, click Done.
  3. Open menu → System Settings → Privacy & Security, scroll to Security, and click Open Anyway next to Laybacker — confirm with your password / Touch ID.
  4. The installer runs. After that, Laybacker opens normally every time.
Windows: on the blue SmartScreen box, click More info → Run anyway.
Independently verified safe
Every release is scanned, signed, and checksummed.
🛡️ VirusTotal · 70+ engines ◉ Open source 🔐 Cryptographically signed 🔢 Checksum verified
Independently verified code quality
SonarCloud Quality Gate SonarCloud Reliability rating SonarCloud Security rating SonarCloud Maintainability rating Test coverage CodeQL security scan

Beyond download safety, the code itself is graded by independent services on every update. SonarCloud rates reliability, security & maintainability — currently A across the board, with zero bugs and zero vulnerabilities. Codecov shows how much of the code its automated tests exercise. CodeQL is GitHub's own security scanner. Click any badge for its live report.

Verify it's genuine

Don't just take our word for it — Laybacker is built to be independently checkable. Five ways to confirm it's safe and untampered:

▸ Open source

The full source is public and every installer is built automatically by GitHub from a tagged commit, with public build logs. Read the code.

▸ Ask an AI to check it

Not a coder? You don't have to be. Give the GitHub link to the AI assistant of your choice — ChatGPT, Claude, Gemini, Copilot, or any other — and ask it to review the code and confirm the app does only what we say it does, and nothing it shouldn't. A second, independent opinion in plain English.

▸ VirusTotal scanned

Each release is scanned by 70+ antivirus engines, with the report links in the release notes. Or scan it yourself at virustotal.com.

▸ Checksums

Every release publishes SHA256SUMS files so you can confirm your download matches our build exactly, byte for byte.

▸ Signed provenance

Each binary carries a cryptographic attestation tying it to the exact public source. Verify with gh attestation verify <file> --repo soundrich-bot/laybacker.