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Required and optional tools

The application drives external programs. Only FFmpeg is required; every other tool unlocks a family of encoders and is treated as absent-but-fine when it is not installed.

What each tool gives you

Tool Required Unlocks
ffmpeg Yes All encoding. Also decodes source audio for the standalone encoders.
ffprobe Yes Stream inspection - codec, layout, duration, per-stream selection.
opusenc No The standalone opusenc adapter.
qaac No Apple AAC. Also needs a working Apple CoreAudioToolbox installation.
fdkaac No Fraunhofer FDK AAC.
deezy No The five DeeZy Dolby adapters.
dee No Dolby Encoding Engine. Required by every DeeZy adapter.
truehdd No Required by the DeeZy Atmos and AC-4 adapters only.

MediaInfo ships with the application through pymediainfo and needs no installation. It supplies the per-track container delays described in Audio controls.

How tools are found

Discovery runs asynchronously at startup and again whenever you change a path in Settings. For each tool, in order:

  1. The path configured in Settings, if you set one. A configured path that does not point at a file is an error rather than a silent fallback.
  2. PATH. qaac is looked up as qaac64 first, then qaac.
  3. DeeZy's own layout - dee and truehdd only. These can ship beside DeeZy rather than on PATH, so if neither of the above found them the application looks in apps/dee/ and apps/truehdd/ next to the DeeZy executable. DeeZy will also look for those dependencies on it's own via the system PATH.

If FFmpeg or ffprobe cannot be resolved, the application reports the failure rather than starting in a half-working state. Every other tool simply comes back as unavailable, and the encoders that need it are shown as unavailable too.

Capability detection, not just presence

Finding ffmpeg on disk is not enough. The application asks the configured FFmpeg build which encoders and muxers it actually exposes, and an adapter is offered only when its required_ffmpeg_encoders and required_ffmpeg_muxers are all present.

This is why a distribution FFmpeg without libopus or libmp3lame shows those encoders greyed out instead of failing partway through a job.

Checking what was found

Help ▸ Copy diagnostics puts a readable summary on the clipboard. For the machine-readable form, run the executable with --diagnostics:

.\FFMPEGAudioEncoder\FFMPEGAudioEncoder.exe --diagnostics

./FFMPEGAudioEncoder.app/Contents/MacOS/FFMPEGAudioEncoder --diagnostics

./FFMPEGAudioEncoder/FFMPEGAudioEncoder --diagnostics

uv run ffmpeg-audio-encoder --diagnostics

It prints JSON and exits without opening the interface. See Troubleshooting for what each field means.

Installing the optional encoders

None of these are distributed by this project.

  • opusenc is part of opus-tools, packaged by most distributions and available for Windows from the Xiph downloads.
  • qaac is Windows-only and needs Apple's CoreAudioToolbox alongside it. The availability check runs qaac at startup, so a qaac that cannot find CoreAudioToolbox is reported as unavailable rather than failing mid-encode.
  • fdkaac is the Fraunhofer FDK AAC command-line front end.
  • DeeZy requires a licensed Dolby Encoding Engine, and TrueHDD for Atmos and AC-4. Point Settings at deezy and the rest of the toolchain is usually found automatically through the apps/ layout described above.