Jazz Hands

A Windows video editor for game trailers, promo videos and devlogs, with a headless engine that can be driven completely from the command line. Every edit you can make in the editor is also a command: the jazz CLI, a JSON-RPC control server and an MCP server, so an AI assistant such as Claude Code can build and change a project, look at frames, and export, live in a running editor or with no window at all.

• Multi-track timeline with compositing, keyframes, effects, transitions, titles and colour tools
• GPU decoding, compositing and NVENC export (Direct3D 11, FFmpeg 8.1)
• Smart cut: trims long recordings without re-encoding, except the frames around each cut
• Every audio stream of a recording (for example OBS's game, mic and chat tracks) as its own lane
• Speech to text, captions and editing by deleting words, all on your own machine
• Projects are readable JSON with a published schema (Docs/schema)

Download

Get the latest from the Releases page (previews until 1.0.0 is out), or build from source. Each release has two downloads:

• JazzHands-<version>-win-x64.msi installs for the current user, with no administrator rights, and puts jazz on your PATH.
• JazzHands-<version>-portable-win-x64.zip runs from any folder and leaves the registry alone.

The builds are not code signed, so Windows SmartScreen asks once: More info, then Run anyway.

Requirements

• Windows 11, x64
• A Direct3D 11 GPU. An NVIDIA GPU is recommended for hardware decoding and NVENC export; without one Jazz Hands decodes and encodes in software.
• Background removal runs on the GPU through the DirectML that comes with Windows, or on the CPU where Windows has none new enough.

Build from source

You need the .NET 10 SDK and PowerShell.

git clone https://github.com/Sweet-Karmaz-Studios/Jazz-Hands.git
cd Jazz-Hands
powershell -ExecutionPolicy Bypass -File tools\get-ffmpeg.ps1
dotnet build JazzHands.slnx -c Release

get-ffmpeg.ps1 downloads the pinned FFmpeg build into third_party\ffmpeg and checks its SHA-256. The editor is then at src\JazzHands.App\bin\Release\net10.0-windows10.0.22621.0\win-x64\JazzHands.exe and the CLI at src\JazzHands.Cli\bin\x64\Release\net10.0-windows10.0.22621.0\win-x64\jazz.exe.

To make the installer and the portable zip yourself:

powershell -ExecutionPolicy Bypass -File tools\publish.ps1

They land in artifacts\release\<version>. The installer needs the WiX Toolset 5 command line (dotnet tool install --global wix) with its UI and Util extensions; -SkipInstaller builds only the folder and the zip.

Driving it from the command line

jazz new trailer.jazz --fps 60 --size 3840x2160
jazz media add trailer.jazz .\captures\*.mp4
jazz frame trailer.jazz --at 00:00:12.500 --out check.png
jazz export trailer.jazz --preset youtube-4k

jazz --help lists every command, and Docs/CLI.md is the full reference. jazz mcp runs the MCP server; jazz mcp --attach connects it to a running editor so changes appear as they are made.

Licence

Jazz Hands is licensed under the GNU General Public License, version 3 (LICENSE.txt), because it ships the GPL build of FFmpeg. LICENSES.md lists every third-party component and its licence.

Copyright (c) Sweet Karmaz Studios.