Laszlo

Laszlo is a Python library for creating flexible audio loopers. Watch the showcase:

How to use

Create a new song with one track that simply monitors the input until a button is pressed:

from laszlo.engine import *
song = Program()
track = song.add_track('my track')
snippet = track.add_snippet(
	source = Input(),
	start = events.Boot(),
	end = events.ButtonPress()
)
song.start()

After the button press, loop the previous snippet:

# Insert this before the previous `song.start()`
snippet_loop = track.add_snippet(
	source = snippet,
	start = snippet.end,
	repeat = -1
)
song.start()

Overdub bass while the loop is playing, until the next button press, and then loop that:

bass = song.add_track('bass')
bass_snippet = bass.add_snippet(
	source = Input(),
	start = snippet_loop.start,
	end = events.ButtonPress(),
	fx = [effects.PitchShift(-12)]
)
bass_loop = bass.add_snippet(
	source = bass_snippet,
	start = bass_snippet.end,
	repeat = -1
)
song.start()

Installation

Using pip

wget https://github.com/davidhusz/laszlo/releases/download/v0.1.0/laszlo-0.1.0-py3-none-any.whl
pip install laszlo-0.1.0-py3-none-any.whl

After that you can launch the editor with:

python3 -m laszlo.gui

To view an example file:

wget -qO- https://raw.githubusercontent.com/davidhusz/laszlo/main/examples/simple-song.laszlo \
	| python3 -m laszlo.gui -

On Raspberry Pi

Installation on Raspberry Pi works a little differently than for other Linux platforms. Since the Pi only makes use of the audio engine (not the GUI), the only necessary dependency is pyo. However, trying to install pyo using pip on a Raspberry Pi will not work. You should instead install it using:

sudo apt install python3-pyo

We will also need venv:

sudo apt install python3-venv

After that you can install laszlo with:

# the system site packages directory contains our pyo package
python3 -m venv --system-site-packages laszlo-venv
source laszlo-venv/bin/activate
wget https://github.com/davidhusz/laszlo/releases/download/v0.1.0/laszlo-0.1.0-py3-none-any.whl
python3 -m pip install --no-dependencies laszlo-0.1.0-py3-none-any.whl

Run an example file with:

python3 <(wget -qO- https://raw.githubusercontent.com/davidhusz/laszlo/main/examples/simple-song.py)

How to build

The package

Requires sass.

git clone https://github.com/davidhusz/laszlo.git
cd laszlo
sass src/laszlo/gui/editor.sass src/laszlo/gui/editor.css
python3 -m build

Standalone executable for Windows

Run the same commands as for building the package, excluding python3 -m build, but using a Windows shell rather than a *nix shell. After that, switch into WSL and run ./create-standalone-binary.sh. If it succeeded, the binary will be saved under ./dist.

FAQ/Troubleshooting

I can't hear the input signal/I'm hearing the wrong input channel

Try changing the pyo.Input(chnl=1) argument to 0 in of src/laszlo/engine/main.py. Or do it with this command:

sed 's/pyo.Input(chnl=1)/pyo.Input(chnl=0)/' -i "$(dirname "$(python3 -c 'import laszlo; print(laszlo.__file__)')")/engine/main.py"