Extract clean audio from video files with FFmpeg.

Demux

Demux is a native Rust desktop application for extracting audio from local video files. It makes the FFmpeg workflow visible and approachable: add media, inspect what was found, choose how and where to save the audio, then follow the queue through completion, failure, cancellation, or pause.

Status: active development. The extraction workflow is functional, and tagged releases publish portable Linux archives and Debian packages for Linux x86_64. Native installers for additional platforms are not yet available.

Current capabilities

• Add individual files or folders, or drop them into the application. Folder imports discover supported media recursively and preserve a stable queue order.
• Probe each item asynchronously with FFprobe, show the discovered media details, and keep invalid, duplicate, or unreadable inputs from blocking valid work.
• Extract eligible jobs sequentially as MP3 with validated 128–320 kbps bitrate, 44.1/48 kHz sample-rate, and mono or stereo output.
• Choose an output folder, preserve safe paths from folder imports, and avoid overwriting existing files by selecting a numbered filename.
• Copy allowlisted metadata and compatible embedded artwork when enabled.
• Optionally apply two-pass EBU R128 loudness normalization targeting −23 LUFS with a decoded −1 dBTP ceiling.
• Follow active work through percentage, elapsed time, speed, bitrate, output size, and remaining-time estimates when FFmpeg provides those values.
• View bounded, timestamped FFmpeg output in the app, then clear or export the retained log without affecting structured tracing.
• Cancel the entire queue safely, including partial-output cleanup. Unix builds also support pause and resume through a dedicated FFmpeg process group; unsupported platforms report that limitation explicitly.
• Open Settings for dependency rechecks, saved-default reset, window geometry retention, and shortcut guidance; About links the project, FFmpeg, and the GPL-3.0-only license.
• Use the compact responsive layout at narrower window widths, with Start Ripping anchored in Progress and dialogs protecting active work on close.

Supported intake extensions are MP4, MKV, MOV, AVI, WMV, FLV, MPEG, and MPG. Whether a file can be extracted still depends on the codecs available to the locally installed FFmpeg build.

Requirements

• FFmpeg available as ffmpeg on PATH
• FFprobe available as ffprobe on PATH
• A desktop environment supported by Iced

Building from source additionally requires Rust and Cargo. FFmpeg and FFprobe are not needed merely to compile or run the unit tests, but Demux checks for both before it accepts work.

Linux note

Demux currently uses X11 or XWayland on Linux. Iced 0.14 does not emit desktop file-drop events through its Wayland backend, so native Wayland support remains disabled until that upstream capability is available.

Install a release

Linux release archives, Debian packages, and SHA-256 checksums are published on the GitHub Releases page.

On Debian or Ubuntu x86_64, install the .deb package with:

sudo apt install ./demux_0.1.3_amd64.deb

The package installs FFmpeg and the desktop launcher as Debian dependencies. Replace 0.1.3 with the version you downloaded. To use the portable archive instead, install FFmpeg with your distribution's package manager, verify the download, extract it, and launch demux:

sha256sum --check demux-0.1.3-x86_64-unknown-linux-gnu.tar.gz.sha256
tar -xzf demux-0.1.3-x86_64-unknown-linux-gnu.tar.gz
cd demux-0.1.3-x86_64-unknown-linux-gnu
./demux

See INSTALL.md for distribution-specific FFmpeg commands, troubleshooting, and optional desktop integration. See docs/RELEASING.md for the package build and release procedure.

Build from source

From the repository root:

cargo run

Then add one or more videos, confirm the output folder and MP3 settings, and select Start Ripping. Existing output files are never overwritten: Demux chooses the next available numbered name instead.

For additional runtime diagnostics, enable tracing before launching:

RUST_LOG=demux=debug cargo run

Release builds write structured tracing to human-readable daily log files. Files are named demux.YYYY-MM-DD.log; the seven most recent files are retained in the following locations:

• Linux: $XDG_STATE_HOME/demux/logs, or ~/.local/state/demux/logs.
• macOS: ~/Library/Logs/Demux.
• Windows: %LOCALAPPDATA%/Demux/logs.

Set DEMUX_LOG_DIR to choose an alternate directory. RUST_LOG also applies to release log files; it defaults to demux=info. The production tracing files are separate from the bounded FFmpeg log shown in the application and exported with Save Log.

Development

The same checks used by continuous integration are useful before submitting a change:

cargo fmt --all -- --check
cargo clippy --all-targets --all-features -- -D warnings
cargo test --all-targets --all-features

The FFmpeg normalization and pause/resume integration tests require local FFmpeg and FFprobe, and are therefore ignored by default. Run them explicitly when those tools are available:

cargo test --test ffmpeg_normalization -- --ignored
cargo test --test ffmpeg_pause -- --ignored

Architecture

The FFmpeg engine remains independent of the Iced view layer. The GUI renders state and forwards explicit actions; application and adapter layers own probing, command construction, process management, progress parsing, logging, and recovery.

Iced UI
  ↓ messages and state updates
Application model
  ↓ jobs and settings
FFmpeg service
  ├── ffprobe: inspect media
  ├── ffmpeg: extract audio
  └── bounded progress and log events: update the UI

Demux is the GUI composition root. Each substantial surface owns its local state, messages, initialization, update logic, and view; the root maps child tasks when a workflow crosses a boundary.

Demux
  ├── Queue            → intake, probing, selection, and job presentation
  ├── Progress         → active extraction measurements and controls
  ├── Logs             → bounded FFmpeg output, retention, and export
  ├── OutputSettings   → encoding and destination choices
  ├── ApplicationSettings → preferences, dependencies, and shortcuts
  ├── About            → product identity and external links
  ├── CloseConfirmation → safe shutdown while extraction is active
  ├── WindowState      → persisted geometry and responsive layout state
  └── Notifications    → transient completion and failure feedback

Subsystem adapters retain their specific error types. Application runtime operations promote failures into the unified demux::Error, and the GUI turns them into persistent job state or user-facing messages only at its boundary.

Roadmap

Milestones 0–10 are complete: GUI composition, intake, sequential execution, live progress, cancellation, configurable MP3 output, metadata/artwork, normalization and folder structure, FFmpeg logs, Unix pause/resume, and the complete responsive shell with preferences, dialogs, shortcuts, and safe close.

See ROADMAP.md for the engine-first milestone plan and its exit criteria.

License

Demux is licensed under the GNU General Public License v3.0 only.