SSTV - Slow Scan Television Decoder & Encoder

A robust TypeScript library and CLI tool for decoding and encoding Slow Scan Television (SSTV) signals.

Features

• Decode SSTV audio (WAV) into images (PNG).
• Encode images (PNG) into SSTV audio (WAV).
• High Precision frequency analysis for accurate color rendering.
• CLI for easy terminal usage.
• TypeScript API for programmatic integration.
• Supports Martin 1 mode (with architecture for more).

Installation

npm install sstv

CLI Usage

Decoding

Decode a WAV file containing an SSTV signal:

sstv -d input.wav -o output.png

Encoding

Encode a PNG image into an SSTV audio signal:

sstv -e input.png -o output.wav

Options

• -d, --decode <file>: Input WAV file to decode.
• -e, --encode <file>: Input PNG file to encode.
• -o, --output <file>: Output file path (default: result.png or result.wav).
• -m, --mode <mode>: SSTV mode for encoding (default: "Martin 1").
• -s, --skip <seconds>: Skip the first N seconds of the audio file.
• --list-modes: List all supported modes.
• -h, --help: Show help message.

Programmatic Usage

Decoder

import { readWav, SSTVDecoder } from 'sstv';
import * as fs from 'fs';

// Read WAV file
const { samples, sampleRate } = await readWav('input.wav');

// Create decoder
const decoder = new SSTVDecoder(samples, sampleRate);

// Decode
const png = decoder.decode();

// Save image
if (png) {
    png.pack().pipe(fs.createWriteStream('output.png'));
}

Encoder

import { SSTVEncoder, spec, writeWav } from 'sstv';
import { PNG } from 'pngjs';
import * as fs from 'fs';

// Load PNG
const png = PNG.sync.read(fs.readFileSync('input.png'));

// Create encoder
const encoder = new SSTVEncoder();

// Encode (Martin 1)
const samples = encoder.encode(png, spec.M1);

// Save WAV
await writeWav('output.wav', { samples, sampleRate: 48000 });

Supported Modes

Mode	Decode	Encode
Martin 1	✅	✅
Martin 2	✅	❌
Scottie 1	✅	❌
Scottie 2	✅	❌
Scottie DX	✅	❌
Robot 36	✅	❌
Robot 72	✅	❌

License

MIT