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LosslessCut

Command line interface (CLI)

LosslessCut has basic support for automation through the CLI. See also HTTP API.

Terminal window
LosslessCut [options] [files]

Note that these examples assume that you have set up the LosslessCut executable to be available in your PATH (command line environment). Alternatively you can run it like this:

Terminal window
# First navigate to the folder containing the LosslessCut app
cd /path/to/directory/containing/app
# Then run it
# On Linux:
./LosslessCut arguments
# On Windows:
./LosslessCut.exe arguments
# On MacOS:
./LosslessCut.app/Contents/MacOS/LosslessCut arguments

Note that some users have reported that the Windows Store version of LosslessCut needs an app execution alias.

Open one or more files:

Terminal window
LosslessCut file1.mp4 file2.mkv

Override settings (experimental) 🧪

See available settings. Note that this is subject to change in newer versions. Settings are validated, and if the JSON or any key or value is invalid, none of them are applied (see the log for details). You may use JSON or JSON5. Example:

Terminal window
LosslessCut --settings-json '{captureFormat:"jpeg", "keyframeCut":true}'

Override FFmpeg/FFprobe path

Overriding path to FFmpeg/FFprobe can be done in the UI, or with the following command:

Terminal window
LosslessCut --settings-json '{customFfPath:"/path/to/folder/containing/ffmpeg_and_ffprobe"}'

Other options

  • --locales-path Customise path to locales (useful for translators).
  • --disable-networking Make app completely offline (see #1418).
  • --http-api Start the HTTP server with an API to control LosslessCut, optionally specifying a port (default 8080).
  • --keyboard-action Run a keyboard action (see below.)
  • --config-dir Path to a directory where the config.json file will be stored and loaded from. Note: don’t include config.json in the path (only the directory containing it).

Controlling a running instance (experimental) 🧪

If you have the “Allow multiple instances” setting disabled (the default), you can control a running instance of LosslessCut from the outside, using for example a command line. You do this by issuing messages to it through the LosslessCut command. Currently only keyboard actions are supported, and you can open files. Note that this is considered experimental and the API may change at any time.

Open files in running instance

Terminal window
LosslessCut file1.mp4 file2.mkv

Keyboard actions, --keyboard-action

Simulate a keyboard press action in an already running instance of LosslessCut (if none is running, or “Allow multiple instances” is enabled, the action is ignored). Arguments are JSON or JSON5. Note that the command will return immediately, so if you want to run multiple actions in a sequence, you have to sleep for a few seconds between the commands. Alternatively if you want to wait until an action has finished processing, use the HTTP API instead.

Available keyboard actions

A list of the available action names can be found in the “Keyboard shortcuts” dialog in the app. Note that you don’t have to bind them to any key before using them.

Example keyboard actions

Open a file and export it:

Terminal window
# Open a file in an already running instance
LosslessCut file.mp4
sleep 3 # hopefully the file has loaded by now
# Export the currently opened file
LosslessCut --keyboard-action export

Seek to specific time in the media:

Terminal window
LosslessCut --keyboard-action goToTimecodeDirect '{"time": "12.23"}'

Actions that open a dialog cannot be scripted

Some actions, for example createNumSegments, createFixedDurationSegments or selectSegmentsByExpr, open a dialog where you have to enter something. These cannot be fully automated, because there’s no way to pass the dialog’s values from the command line: the action will just open the dialog in the app.

Instead, to create segments from a script, write a project file next to the media file. If the media file is /path/to/video.mp4, name the project file /path/to/video-proj.llc, and LosslessCut will load it automatically when you open the media file. Times are in seconds, name is the segment label:

{
  version: 2,
  mediaFileName: 'video.mp4',
  cutSegments: [
    { start: 0, end: 10, name: 'First' },
    { start: 20, end: 30, name: 'Second' },
  ],
}

Then open the file and export it using --keyboard-action export, or better the HTTP API, which waits for most actions to finish before responding. Note that by default export first opens the export options dialog, so either turn that dialog off (--settings-json '{exportConfirmEnabled:false}') or send export twice. You can also open an .llc file directly (LosslessCut /path/to/video-proj.llc), see the batch example.

HTTP API

You can also control a running instance with the HTTP API.