losslesscut-mcp

Let Claude and other AI assistants see your videos and cut them with LosslessCut.

An MCP server that looks at your media with FFmpeg (frames, scenes, silence, loudness, keyframes) and drives LosslessCut through its local HTTP API. Ask "keep the colour bars and the last 3 seconds and export them" and get the files, cut losslessly.

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Real run against LosslessCut 3.70.2: every step is an MCP tool call, the screenshots are the LosslessCut window.

What it can do

See and analyse the media

These run locally with FFmpeg and work on any file, with or without LosslessCut open. They mirror what LosslessCut itself can show or detect.

Control LosslessCut

The cutting itself is done by LosslessCut and FFmpeg without re-encoding, exactly as if you clicked the buttons.

Related MCP server: Video MCP

Requirements

• LosslessCut 3.70 or newer (tested with 3.70.2 on Windows 11)

• Node.js 20 or newer

• FFmpeg and FFprobe on your PATH for the analysis tools (or set LOSSLESSCUT_MCP_FFMPEG / LOSSLESSCUT_MCP_FFPROBE; LosslessCut ships both in its resources folder)

• An MCP client: Claude Desktop, Claude Code, or any other client that supports stdio servers

1. Start LosslessCut with the HTTP API

The API is off by default. Start LosslessCut from a terminal with --http-api:

# Windows
"C:\path\to\LosslessCut.exe" --http-api

# macOS
/Applications/LosslessCut.app/Contents/MacOS/LosslessCut --http-api

# Linux
./LosslessCut --http-api

It listens on 127.0.0.1:8080. To use another port, pass it: --http-api 8081, and set LOSSLESSCUT_PORT=8081 for this server too. See LosslessCut's HTTP API docs.

2. Add the server to your client

Claude Code

claude mcp add losslesscut -- npx -y github:bariswha/losslesscut-mcp

Claude Desktop

Open Settings → Developer → Edit Config and add this to claude_desktop_config.json, then restart Claude Desktop:

{
  "mcpServers": {
    "losslesscut": {
      "command": "npx",
      "args": ["-y", "github:bariswha/losslesscut-mcp"],
      "env": { "LOSSLESSCUT_PORT": "8080" }
    }
  }
}

Other MCP clients

Any client that can start a stdio server works. Use the command npx -y github:bariswha/losslesscut-mcp, or run it from a clone:

git clone https://github.com/bariswha/losslesscut-mcp.git
cd losslesscut-mcp
npm ci
node src/index.js --port 8080

3. Ask

• "Open D:\Videos\talk.mp4 in LosslessCut."

• "Look through this video and tell me where the scenes change."

• "Cut out the silent pauses longer than a second and export the rest as one file."

• "Find the loudest moments, make a 20 second segment around each and export them."

• "Keep 0:02–0:05 and 0:07–0:09.5, name them intro and demo, and export."

Give the assistant full file paths. It is told never to guess them, and every tool rejects relative paths and files that don't exist.

Configuration

For example, without frames in Claude Code:

claude mcp add losslesscut -e LOSSLESSCUT_MCP_FRAMES=off -- npx -y github:bariswha/losslesscut-mcp

Most clients can also switch single tools on and off in their own settings: for example the tools menu in Claude Desktop, or /mcp and permission rules in Claude Code.

Security

• Talks only to LosslessCut on 127.0.0.1. No other network access, no telemetry. Analysis runs locally with FFmpeg.

• Never sends an Origin header, so LosslessCut's browser protection stays meaningful for everything else.

• FFmpeg and FFprobe are started directly with an argument list, never through a shell.

• run_action only runs actions from a fixed allowlist. quit, cleanupFilesDialog (which can move source files to the trash), openSendReportDialog and the URL download action are blocked.

• All inputs are validated: times are parsed and range-checked, paths must be absolute, existing files without control characters.

• set_segments writes LosslessCut's project file next to the media (<name>-proj.llc) and renames an existing one to a .bak backup first. Nothing else is written, except the exports you ask for.

• LosslessCut's HTTP API has no authentication: while it runs with --http-api, any program on your computer can control it. Only enable it while you use it.

See SECURITY.md.

Limitations

These come from LosslessCut's experimental HTTP API:

• No read access. The API can't report the open file, the segments or the playhead, so the assistant keeps track of what it did. The analysis tools read the file itself, not the app.

• No error feedback. An action that fails inside LosslessCut still returns success over HTTP.

• Dialogs. If LosslessCut opens a dialog (for example when a file is already open), the action waits for you; the server reports that after 30 seconds. Actions in the dialog group of list_actions always open one.

• Timecode format. seek sends hh:mm:ss.fff, which LosslessCut parses with its default timecode format. If you switched it to frames or seconds, use set_segments instead.

• Lossless cuts snap to keyframes unless smart cut is on in LosslessCut, so exports can start a little earlier than asked. keyframes shows where.

Development

npm ci
npm test

Tests run against a fake LosslessCut HTTP server, and the analysis tests run real FFmpeg on a generated video when FFmpeg is installed.

Not affiliated

losslesscut-mcp is an independent project. It is not affiliated with, endorsed by or maintained by LosslessCut or its author. LosslessCut is © Mikael Finstad and licensed under GPL-2.0.

License

MIT. This server is a separate program that talks to LosslessCut over HTTP and runs FFmpeg as a separate process. It contains no LosslessCut or FFmpeg code, so their licences don't extend to it, and using it doesn't change how you may use them.