How to Install the FFmpeg Library for Audacity (Windows and Mac)

You hit Export, pick M4A or WMA, and Audacity tells you the FFmpeg library isn't found. You install FFmpeg, click Locate, point it at the folder, and Audacity still says it can't find it. The download wasn't the problem.

Quick answer: To install the Audacity FFmpeg library, download the FFmpeg build whose avformat version matches your Audacity version, then go to Edit > Preferences > Libraries > FFmpeg Library > Locate and select avformat-XX.dll on Windows or libavformat.XX.dylib on macOS. Audacity only loads a fixed set of avformat versions per release, so installing the newest FFmpeg is the most common reason Locate fails.

Why "just install the latest FFmpeg" is wrong advice

Conventional wisdom says grab FFmpeg from the official site and point Audacity at it. Most setups produce exactly one result: a dialog that keeps saying the library wasn't found. It isn't a path problem or a permissions problem. It's an ABI problem.

Audacity doesn't call the ffmpeg command-line tool. It links against FFmpeg's shared libraries directly, mainly libavformat, libavcodec, and libavutil. Each FFmpeg major release bumps those library sonames, and Audacity ships a hardcoded list of the sonames it knows how to talk to. If your avformat number isn't on that list, Audacity refuses the file no matter where it lives.

That's why a fresh FFmpeg 8 install fails on Audacity 3.3, and why a five-year-old forum post telling you to install "the FFmpeg library" still gets upvoted while helping nobody.

Which FFmpeg version your Audacity needs

Check Help > About Audacity first, then match the row:

Newer Audacity releases keep the older numbers, so a 3.5 install will happily load avformat-58 from an ancient build. The reverse never works. Audacity 3.1 will never load avformat-61, and no amount of re-clicking Locate changes that.

Audacity 3.x on Windows is 64-bit only, so you need 64-bit FFmpeg DLLs. If you're still on Audacity 2.4.2, that's a 32-bit app and needs 32-bit libraries.

How to install FFmpeg for Audacity on Windows

The path of least resistance is the FFmpeg installer that Audacity's own support pages link to, hosted at lame.buanzo.org. It drops the DLLs in a folder Audacity already checks and usually needs zero manual work.

If you'd rather use an official build, download a shared build, not a static one. On gyan.dev that's ffmpeg-release-full-shared.7z; BtbN's builds label them shared too. Static builds contain a single ffmpeg.exe with no DLLs at all, which is the second most common reason Locate fails. Extract the archive somewhere permanent like C:\ffmpeg\, then point Locate at C:\ffmpeg\bin\avformat-XX.dll.

One trap in the Locate dialog itself: the file type dropdown often defaults to a filter that hides everything except one exact filename. Switch it to "Dynamically Linked Libraries (.dll)" or "All Files (.*)" or you'll stare at an empty folder that definitely contains your DLL.

How to install FFmpeg for Audacity on macOS

On macOS, install the FFmpeg .pkg linked from Audacity's support site rather than using Homebrew. The installer places the dylibs under /Library/Application Support/audacity/libs/, which Audacity scans automatically on launch.

Gatekeeper will likely block it on first run since the package isn't notarized by Apple. Right-click the .pkg and choose Open, or go to System Settings > Privacy & Security and click "Open Anyway" after the first blocked attempt. Then restart Audacity and check Audacity > Settings > Libraries.

The Homebrew mismatch nobody warns you about

brew install ffmpeg gives you a working command-line FFmpeg and an Audacity that still can't see it. This is documented in audacity/audacity issue #3747, and there are two separate things going wrong.

First, versions. Homebrew tracks the current FFmpeg release, so /opt/homebrew/lib/ (Apple Silicon) or /usr/local/lib/ (Intel) will hold a dylib several majors ahead of what your Audacity accepts. Run ls /opt/homebrew/lib/libavformat* and read the number before you blame anything else.

Second, code signing. Audacity's official macOS build ships with the hardened runtime and library validation enabled, which means it will only load dylibs signed by the same team ID or by Apple. Homebrew's bottles aren't. Even when the version number lines up perfectly, the load gets rejected at the OS level and Audacity reports the same generic failure. The .pkg exists precisely to sidestep this, so use it.

If you're on Apple Silicon, also confirm you're not mixing architectures. An x86_64 Audacity running under Rosetta cannot load arm64 dylibs, and file /opt/homebrew/lib/libavformat.dylib will tell you which you have.

Common pitfalls

When the GUI stops being the right tool

Installing this once for occasional exports is fine. Doing it on three machines so a team can hand-export the same M4A settings every week is a workflow problem wearing a codec costume.

Here's the split. Audacity is an editor: waveform selection, noise reduction, a human deciding where a cut goes. But "take this WAV, normalize it, encode to 128 kbps AAC, name it by episode number" is a batch job. Nobody should be clicking through an export dialog 40 times.

That's the shape FFmpeg Micro fits: the same FFmpeg operations as a REST call, or as a step in n8n, Make, or Zapier, or as a tool call from an AI agent. If you're already thinking in FFmpeg terms, the -map flag guide covers stream selection for multi-track audio, and replacing audio in video walks the track-swap version of the same idea.

FAQ

Why does Audacity say the FFmpeg library was not found after I installed it?

Almost always a version mismatch. Audacity only loads specific avformat sonames per release, so if you installed FFmpeg 8 (avformat-62) on Audacity 3.3 (which tops out at avformat-60), it will report the library as missing even with a correct path.

Do I need FFmpeg to export MP3 from Audacity?

No. Audacity has included the LAME MP3 encoder internally since version 2.3.2, so MP3 export works with a clean install. You need the FFmpeg library for M4A/AAC, WMA, AC3, and AMR export, and for importing container formats like MP4, MKV, and WMV.

Where does Audacity look for the FFmpeg library by default?

On Windows it checks C:\Program Files\FFmpeg for Audacity\ and the Audacity program folder. On macOS it checks /Library/Application Support/audacity/libs/. Anywhere else works too, but you have to point at it manually through Edit > Preferences > Libraries > Locate.

Can I use Homebrew's FFmpeg with Audacity on macOS?

Usually not. Homebrew ships a much newer FFmpeg than your Audacity accepts, and Homebrew's dylibs aren't signed in a way that passes Audacity's hardened runtime library validation. Install the FFmpeg .pkg from Audacity's support site instead.

Which FFmpeg version do I need for Audacity 3.7?

Audacity 3.7 accepts avformat-55 through avformat-62, which covers FFmpeg 2.x through 8.x. It's the most permissive release so far, which is also why version-matching advice written for 3.7 breaks people running 3.2.

If you'd rather stop maintaining FFmpeg on every machine, the Learn hub covers the API equivalents of common conversions, and you can try a transcode against your own file in the playground before writing any code. Sign up free when you want it running on a schedule instead of in a dialog box.