UltimateSlice

Getting Started

Requirements

  • Linux (GTK4 + GStreamer stack)
  • Rust (stable, via rustup)
  • GStreamer plugins: gstreamer, gstreamer-plugins-base, gstreamer-plugins-good, gstreamer-plugins-bad
  • ffmpeg (for export — must be on $PATH)

Install dependencies on Ubuntu/Debian:

sudo apt install 
  libgtk-4-dev 
  libgstreamer1.0-dev 
  libgstreamer-plugins-base1.0-dev 
  gstreamer1.0-plugins-good 
  gstreamer1.0-plugins-bad 
  gstreamer1.0-libav 
  ffmpeg

Building & Running (Source)

git clone https://github.com/kmwallio/UltimateSlice.git
cd UltimateSlice
cargo run

Flatpak

A Flatpak manifest is provided at io.github.kmwallio.ultimateslice.yml.

flatpak-builder build-dir io.github.kmwallio.ultimateslice.yml --user --install --force-clean
flatpak run io.github.kmwallio.ultimateslice

The Flatpak includes permissions for external drives (/run/media) to allow importing footage from external SSDs.

For the MCP server mode (for AI agent control):

cargo run -- --mcp

First Launch

The application opens with an Untitled project containing one Video track and one Audio track.

Window Layout

┌──────────────────────────────────────────────────────────────────┐
│  Toolbar (New / Open / Recent / Save / Settings / Export / Undo / Redo)  │
├────────────────┬─────────────────────────────┬────────────────────┤
│  Media Library │   Source Monitor            │  Inspector         │
│                │   (source preview)          │  (clip properties) │
├────────────────┴─────────────────────────────┤                    │
│   Program Monitor (assembled timeline view)  │                    │
├──────────────────────────────────────────────┴────────────────────┤
│   Timeline (multi-track, ruler, clips)                            │
└───────────────────────────────────────────────────────────────────┘

Creating a New Project

  • Click New in the toolbar (or press Ctrl+N).
  • Click ⚙ Settings to configure canvas resolution and frame rate.
  • Use Save… (Ctrl+S) to save as FCPXML at any point.

Opening an Existing Project

  • Click Open… (Ctrl+O) and select a .fcpxml file.
  • Or click Recent ▾ to pick from the last 10 opened/saved projects.
  • UltimateSlice reads the FCPXML 1.10 format, including all clip properties, markers, and effects.
  • Project file read/parse runs off the GTK main thread, so the UI remains responsive while opening larger timelines.

Keyboard Shortcuts

See Shortcuts for the full reference.
Press ? or / in the timeline to open the in-app shortcut overlay. Use Ctrl+, to open Preferences.