OCTA SLICER

I needed a way to prep longer samples from songs or audio clips into smaller files before loading them onto the Octatrack. I don't like resampling or manually creating new slices every time I want to chop a longer sample on the OT.

This is a tool that lets you visually slice a long sample into however many parts you want (8, 16, 32, etc), preview each slice, adjust the start/end points, and export them all as separate Octatrack-ready WAV files. Batch loading allows for multiple samples, and everything exports as 16-bit/44.1kHz mono so it's good to go directly onto the OT. Happy slicing!

Installation

# Clone the repository
git clone https://github.com/danielesiegel/octa-sample-prep.git
cd octa-sample-prep

# Install dependencies
pip install -r requirements.txt

# Run the application
python octa_slicer.py

Dependencies

Required:

• numpy - Audio data processing

Recommended:

• soundfile - Load various audio formats (WAV, AIFF, FLAC, MP3, OGG)
• scipy - High-quality resampling
• sounddevice - Audio playback

Without optional dependencies, only WAV files are supported and playback uses macOS afplay.

Keyboard Controls

Key	Action
L	Load audio file
B	Batch load multiple files
O	Set output directory
S	Cycle slice count (4/8/16/32/64)
Space	Play current slice
+ / =	Move slice position right
- / _	Move slice position left
Shift + +/-	Move position (10x faster)
Up / Down	Select previous/next slice
Left / Right	Toggle editing start/end point
Enter	Process and export slices
Q / Esc	Quit

Output Format

All exported slices are automatically converted to Octatrack-compatible format:

• Format: WAV (PCM)
• Bit Depth: 16-bit
• Sample Rate: 44,100 Hz
• Channels: Mono

File Naming

Output files are named: [original-filename]-[slice-number].wav

Example: drums.wav sliced into 16 parts becomes:

drums-1.wav
drums-2.wav
...
drums-16.wav

Usage Example

1. Press L to load an audio file
2. Press S to select the number of slices (default: 16)
3. Use Up/Down to navigate between slices
4. Use +/- to adjust slice start/end positions
5. Press Left/Right to toggle between editing start or end
6. Press Space to preview the current slice
7. Press O to set output directory (default: ~/Desktop/OctaSlices)
8. Press Enter to export all slices

Batch Processing

1. Press B to select multiple audio files
2. Edit slices for the first file
3. Press Enter to export - automatically advances to next file
4. Repeat until all files are processed

Technical Details

Display Simulation

The application simulates the Octatrack's 128x64 pixel backlit LCD:

• Each "pixel" is rendered as a 6x6 screen pixel block
• Custom 5x7 and 3x5 bitmap fonts for text
• Monochrome white-on-black display

Audio Processing

• Automatic resampling from any sample rate to 44.1kHz
• Normalization of clipping audio
• Validation of exported WAV files

License

MIT License - See LICENSE for details.

Acknowledgments

• Inspired by the Elektron Octatrack
• Based on patterns from auto-slicer and audio-slicer