Run Audacity
Go into Edit > Preferences > Modules
Choose mod-script-pipe (which should show New) and change that to Enabled.
Restart Audacity
Check that it now does show Enabled.

Installation

Download or clone this repository:

git clone https://github.com/ychalier/datamoshing.git
cd datamoshing/audacity-script/

Install the requirements:

pip -m install requirements.txt

Usage

Run Audacity

Run the audacity.py script with the following parameters:

python audacity.py <input-video> <input-filter> <output-video>

The input filter is a preset text file for built-in effects in Audacity such as Filter Curve or Reverb. You'll find some in the filters folder. You can create one by running Audacity, opening the effect, messing around with the parameters, and exporting it as a preset .txt file. Multiple filters can be applied, on multiple lines. Blank lines and lines starting with # are ignored. Expressions between braces are evaluated using Python eval function, depending on the parameter t, the output frame timestamp in seconds (you can write the expression yourself or use tools such as Lagrange Polynomial Editor to build larger ones). Here are some examples:

# Echo with variable decay
Echo:Decay="{0.25 * (1 + math.sin(0.5 * t * 6))}" Delay="1"

# Low-pass with variable cut-off
FilterCurve:f0="{10**(2 + math.sin(t * 6.28))}" f1="{10**(2 + math.sin(t * 6.28)) + 20}" FilterLength="8191" InterpolateLin="0" InterpolationMethod="B-spline" v0="-30" v1="0"

Examples

This grid shows examples for several filter presets.

References

mod-script-pipe documentation
mod-script-pipe test files (location in docs is deprecated)
Audacity Scripting Reference
OSError: [Errno 22] Invalid argument (grrr 🥸)