Movie Graph Editor Python from CMD Line

Development Cinematics & Media
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1

I have lightly modified MovieGraphEditorExample.py to pass in my own queue and graph uassets. This works fine in an interactive Editor session. However, I cannot figure out how to get this to launch from the Command Line.

I have tried using UnrealEditor-Cmd.exe and passing my modified Python script as both -run=pythonscript and -ExecutePythonScript, which seems to begin rendering according to the log before immediately shutting down with no errors or warnings.

What is the right way to do this?

2

Steps to Reproduce

  1. Copy the MovieGraphEditorExample.py to MyProject/Content/Python/MyMovieGraphEditor.py
  2. Add render_queue(unreal.load_asset(“/Game/Cinematics/Sequences/MyRenderQueue.MyRenderQueue”), unreal.load_asset(“/Game/Cinematics/MyRenderGraph.MyRenderGraph”)) at the bottom of the py file.
  3. In an interactive session, import MyMovieGraphEditor
  4. Observe the render happens as expected.
  5. From command line, run C:\Program Files\Epic Games\UE_5.5\Engine\Binaries\Win64\UnrealEditor-Cmd.exe -ExecutePythonScript=C:\MyProject\Content\Python\MyMovieGraphEditor.py
  6. See this in the log

[2025.04.01-20.57.21:764][ 3]LogMovieScene: Starting new camera cut: ‘Shot1_Baked_0’

[2025.04.01-20.57.21:795][ 3]LogMovieRenderPipeline: MovieGraph Finished initializing Camera Cut [1/1] OuterName: [LST01_010] InnerName: Shot1_Baked.

[2025.04.01-20.57.22:751][ 3]LogContentStreaming: Texture pool size now 3000 MB

[2025.04.01-20.57.22:751][ 3]LogCsvProfiler: Display: Metadata set : streamingpoolsizemb=“3000”

[2025.04.01-20.57.23:248][ 3]Cmd: QUIT_EDITOR

…

[2025.04.01-20.57.26:516][ 3]LogMovieRenderPipeline: MovieGraph Finished rendering last shot. Moving to Finalize to finish writing items to disk.

[2025.04.01-20.57.26:535][ 3]LogPython: on_queue_finished_callback Render completed. Success: False

[2025.04.01-20.57.26:535][ 3]LogMovieRenderPipeline: Movie Graph Render completed. Duration: +00:00:05.158

[2025.04.01-20.57.26:535][ 3]LogMovieRenderPipeline: MoviePipelinePIEExecutor: Stalling finished, pipeline has shut down.

…

[2025.04.01-20.57.26:593][ 3]LogSlate: Updating window title bar state: overlay mode, drag disabled, window buttons hidden, title bar hidden

[2025.04.01-20.57.26:593][ 3]LogWorld: BeginTearingDown for /Game/Maps/UEDPIE_0_Cinematic

[2025.04.01-20.57.26:593][ 3]LogSlate: Window ‘Movie Pipeline Render (Preview) [Job 1/1 Total] Current Job: 0% Completed.’ being destroyed

[2025.04.01-20.57.26:601][ 3]LogWorld: UWorld::CleanupWorld for Cinematic, bSessionEnded=true, bCleanupResources=true

[2025.04.01-20.57.26:601][ 3]LogSlate: InvalidateAllWidgets triggered. All widgets were invalidated

[2025.04.01-20.57.26:601][ 3]LogWorldPartition: UWorldPartition::Uninitialize : World = /Game/Maps/UEDPIE_0_Cinematic.Cinematic

[2025.04.01-20.57.26:605][ 3]LogPlayLevel: Display: Shutting down PIE online subsystems

3

I managed to get this all working by invoking a full interactive editor session and running a startup Python script that looks for a render config file to see if any rendering should be performed. In the finished callback for the queue, I use unreal.SystemLibrary.execute_console_command(None, “QUIT_EDITOR”) to close the editor.

Am I missing anything? It seems this is the only way to get Movie Render Graph working with Python automation, as the Python-based runtime Executor only works with -game and MRG isn’t supported in -game, while running via -ExecutePythonScript has the aforementioned problem of shutting down immediately and not waiting for any callbacks. Ultimately it would be more convenient if I could pass arguments directly to the script with -ExecutePythonScript instead of reading a config file from disk, but this works for now.

Thanks for any input!

4

Hey Jesse, you need to add a magic method to keep the editor running, have a look at this tutorial here.

unreal.EditorPythonScripting.set_keep_python_script_alive(True)

5

I don’t know how I missed this page! I’ll give this a try and respond only if it doesn’t work for some reason. Thanks so much!