opentone 0.1.2a2

DTMF tone encoding and decoding in pure Python.

OpenTone

A data-over-sound toolkit in pure Python. OpenTone carries data through an audio channel using a family of schemes — telephone tones, modems, Morse, image transmission, and watermarking — each in its own submodule, sharing one set of WAV / synthesis / Goertzel primitives. The core schemes have no dependencies.

Install

pip install opentone            # core schemes (no dependencies)
pip install opentone[all]       # + image/DSP schemes (numpy, Pillow)

Schemes

Module	What it carries	Dependencies
opentone.dtmf	Telephone-keypad DTMF tones (text or dial strings)	—
opentone.morse	Morse / CW on-off keyed tones	—
opentone.fsk	Bytes over a Bell 202 frequency-shift-keying modem	—
opentone.callerid	Bell 202 caller-ID (SDMF / MDMF) messages	—
opentone.mf	Multi-frequency (R1) 2-of-6 signalling	—
opentone.fec	Reed-Solomon error correction (shared by the modems)	—
opentone.sstv	Images over slow-scan-TV-style FM	numpy, Pillow
opentone.spectrogram	An image painted into the audio spectrogram	numpy, Pillow
opentone.watermark	Hidden data inside existing audio	numpy

Quickstart

DTMF (also re-exported at the top level for backwards compatibility):

from opentone import encode_text, decode

encode_text("hello world", "message.wav")
print(decode("message.wav"))          # "hello world"

Morse:

from opentone import morse
morse.encode_text("SOS", "sos.wav")
print(morse.decode("sos.wav"))        # "SOS"

FSK modem, with optional Reed-Solomon error correction:

from opentone import fsk
fsk.encode(b"arbitrary bytes", "data.wav", nsym=8)
print(fsk.decode("data.wav", nsym=8))  # b"arbitrary bytes"

Caller-ID:

from opentone import callerid
callerid.encode("call.wav", number="5551234567", name="JARBAS AI",
                timestamp="06041530", mdmf=True)
print(callerid.decode("call.wav"))

Image into a spectrogram, and slow-scan-TV image transmission:

from opentone import spectrogram, sstv
spectrogram.encode_image("logo.png", "logo.wav")   # view the WAV's spectrogram
sstv.encode_image("photo.png", "photo.wav", width=160, height=120)
img = sstv.decode_image("photo.wav", width=160, height=120)

Hide data in existing audio:

from opentone import watermark
watermark.embed("song.wav", "marked.wav", b"owner-id")
print(watermark.extract("marked.wav", 8))   # b"owner-id"

Input audio

The tone schemes write 8 kHz mono 16-bit WAV. To decode audio from another source, convert it first:

ffmpeg -i some_file.mp3 -acodec pcm_s16le -ac 1 -ar 8000 out.wav

Documentation

• Quickstart
• DTMF: encoding · decoding · reference
• Morse · FSK modem · Caller-ID · MF signalling
• Error correction
• SSTV · Spectrogram art · Watermarking
• API reference

Runnable scripts are in examples/.

License

MIT