Saving a Script File

A script is just a plain text file. There is nothing special about it - the code you copy from this guide goes into a file, you give it a name ending in .py, and Python can then run it.

What you are going to do

1. Open a new file in a text editor
2. Paste the script into it
3. Save it as wav_to_i2s_header.py
4. Run it from the terminal

Step 1 - Open a file

Option 1 - nano (terminal, no install needed)

Open a terminal and type:

nano wav_to_i2s_header.py

This opens a blank file in the terminal editor, ready to paste into.

Option 2 - any text editor (VS Code, Kate, gedit, etc.)

Open your text editor and create a new file.

Step 2 - Paste the script

Copy this and paste it into the file you just opened.

import sys, wave, struct

input_file  = sys.argv[1]  # e.g. /tmp/clip_i2s.wav
output_file = sys.argv[2]  # e.g. clip.h

# wave module reads and strips the WAV header automatically -
# readframes() returns raw PCM samples only
with wave.open(input_file, 'rb') as f:
    raw = f.readframes(f.getnframes())

# unpack as signed 16-bit little-endian integers (pcm_s16le)
samples = struct.unpack('<' + str(len(raw)//2) + 'h', raw)

lines = [
    '#pragma once',
    '#include <pgmspace.h>',
    'const int16_t audio_data[] PROGMEM = {',
]
chunks = [str(s) for s in samples]
for i in range(0, len(chunks), 16):
    lines.append('  ' + ', '.join(chunks[i:i+16]) + ',')
lines.append('};')
lines.append('const size_t audio_len = sizeof(audio_data);')

with open(output_file, 'w') as f:
    f.write('\n'.join(lines) + '\n')

print('Done: ' + str(len(samples)) + ' samples -> ' + output_file)

Step 3 - Save and close

nano: press Ctrl+O, then Enter to confirm the filename, then Ctrl+X to exit.

Text editor: save as wav_to_i2s_header.py. Make sure it saves as plain text - not a Word document or rich text file. Your home folder (/home/yourname/) or a project folder works well.

Step 4 - Run it

python3 wav_to_i2s_header.py /tmp/clip_i2s.wav clip.h

Place clip.h in your sketch folder - the same directory as your .ino file.