DEV Community

Cover image for Render video and audio from a text file with no window open
naman
naman

Posted on Originally published at infinitedevices.org

Render video and audio from a text file with no window open

#headless #cli #rendering #automation

A headless DAW is one that renders with no window open. Most DAWs and visual tools only run with a window and a mouse. Infinite's engine does not need either. The executable inside the app is also a command-line tool, so a patch can be validated, drawn and rendered from a terminal, a script or a CI job.

This post walks through the loop from the Headless User Guide: describe, write, validate, explain, look and listen, render.

What you need

  • The Infinite app. There is no separate package; the executable inside the app is the tool.
  • A machine with working OpenGL, because frames are drawn by the real GPU pipeline.
  • On Linux, a virtual display. Run each render as xvfb-run -a Infinite ....
  • A text editor. Patches are plain text files ending in .inf.

Patches that use a camera, microphone or MIDI device are refused in headless mode (exit code 4), since there is no hardware to read. Swap them for a file or a generator.

A complete patch in a dozen lines

Save this as hello.inf:

infinite-patch 1
node 1 Source Shape
  id shape
  i shapeType Star
end
node 2 Modulators LFO
  id lfo
end
node 3 Utility Output
  id out
end
cable out 0 shape
mod shape sizeX lfo 0 0 1 0.5
expr shape rotation sin(t) * 90
Enter fullscreen mode Exit fullscreen mode

That is one shape, one LFO and an output. The LFO drives the shape's width, and an expression spins it.

Validate, draw, render 

Infinite --validate hello.inf
Infinite --frame hello.inf 0,1,2 pics/ --contact-sheet sheet.png
Infinite --render hello.inf hello.mp4 --duration 4 --fps 30
Enter fullscreen mode Exit fullscreen mode

--validate loads the file strictly and lists every problem with its line number. --frame draws stills at 0, 1 and 2 seconds plus one labelled contact sheet. --render writes the video.

Ask the engine, do not guess

Two commands save a lot of trial and error:

  • Infinite --describe "<node type>" lists a node's controls with their defaults, ranges and dropdown options.
  • Infinite --explain hello.inf prints the graph that was actually built, so you can check every wire. A patch can validate and still be the wrong patch.

Measure the sound

--audio-summary describes the audio as numbers: loudness, peaks, clipping, silence, a spectrum and a tempo guess.

Infinite --audio-summary hello.inf summary.json --wav out.wav --duration 4
Enter fullscreen mode Exit fullscreen mode

Add --stems id,id --stems-dir dir to write one WAV per named node, or --output node to measure a single Audio Out instead of the whole mix.

Reading the result

The last line printed is always one JSON object with ok, mode, frames, fps, size, audio, elapsed_ms, files, warnings and errors. A script can parse that line and branch on ok without scraping log text.

Where this is useful

  • Regression tests for sound and picture. Render a corpus of patches on every commit and compare the summaries.
  • Batch exports. Produce a hundred variations of a piece from one patch with --set node.param=value.
  • Bots and servers. Take a patch from a chat message and send back a video.

Want to see what a patch looks like before scripting it? Start with the first steps tutorial. Infinite is free and open source for macOS, Windows and Linux. The full flag list is in the Headless User Guide, and the patch format is documented in the repository.

Originally published at https://infinitedevices.org/blog/render-video-and-audio-from-a-text-file.html. Infinite is a free, open-source DAW for visuals, music and code: infinitedevices.org.

Top comments (0)