Audio Files

# Send text to WAV file at 300 baud
echo "CQ CQ CQ DE W1ABC" | minimodem --tx 300 --file call.wav

# Send binary file with compression to FLAC
gzip -c document.pdf | minimodem --tx 1200 -f data.flac

# Create Bell 103 test file
echo "TESTING 123" | minimodem --tx 300 \
  --file test-bell103.wav \
  --samplerate 48000

# Create RTTY recording
echo "THE QUICK BROWN FOX" | minimodem --tx rtty -f rtty-test.wav

# Decode with auto-carrier detection
minimodem --rx 1200 --file signal.wav --auto-carrier

# Decode with custom confidence threshold
minimodem 1200 -f noisy-signal.wav --confidence 1.0

# Decode with higher quality search
minimodem 1200 -f signal.wav --limit 5.0

# Decode with custom frequencies
minimodem 1200 -f signal.wav --mark 1200 --space 2400

# Decode and filter non-printable characters
minimodem 1200 -f signal.wav --print-filter

# Correct - mono audio
echo "HELLO" | minimodem --tx 1200 -f mono.wav

# Using sox
sox stereo.wav -c 1 mono.wav

# Using ffmpeg
ffmpeg -i stereo.wav -ac 1 mono.wav

# Then decode
minimodem 1200 --file mono.wav

#!/bin/bash
# Generate test signals at various baud rates
for baud in 300 1200 4800; do
    echo "TEST at ${baud} baud" | \
        minimodem --tx ${baud} --file test-${baud}.wav
done

# Record and timestamp transmission
DATE=$(date +%Y%m%d-%H%M%S)
cat message.txt | minimodem --tx 1200 -f "tx-${DATE}.flac"

# Compress for long-term storage
xz tx-${DATE}.flac

# Decode recording from radio/phone
minimodem 1200 --file radio-recording.wav > decoded.txt

# Batch process multiple recordings
for file in recordings/*.wav; do
    echo "Processing $file..."
    minimodem 1200 -f "$file" --quiet > "${file%.wav}.txt" 2>/dev/null
done

# Generate reference signal
echo "The quick brown fox jumps over the lazy dog" | \
    minimodem --tx 1200 -f reference.wav

# Add noise (using sox)
sox reference.wav -p synth whitenoise vol 0.1 | \
    sox -m reference.wav - noisy.wav

# Test decode quality
minimodem 1200 -f noisy.wav --confidence 1.0

# Decode from one format and encode to another
minimodem 1200 -f input.wav --quiet 2>/dev/null | \
    minimodem --tx 1200 -f output.flac

# Change sample rate
minimodem 1200 -f input-48k.wav --quiet 2>/dev/null | \
    minimodem --tx 1200 -f output-96k.wav -R 96000

# Time how long it takes to decode
time minimodem 1200 -f long-recording.wav > output.txt

# A 60-second audio file might decode in 2-3 seconds

int sa_sndfile_open_stream(
    simpleaudio *sa,
    const char *backend_device,
    sa_direction_t sa_stream_direction,
    sa_format_t sa_format,
    unsigned int rate, unsigned int channels,
    char *app_name, char *stream_name)
{
    const char *path = stream_name;
    
    // Open file for read or write
    SNDFILE *s = sf_open(path,
        sa_stream_direction == SA_STREAM_RECORD ? SFM_READ : SFM_WRITE,
        &sfinfo);
}

switch ( sa->format ) {
    case SA_SAMPLE_FORMAT_FLOAT:
        n = sf_readf_float(s, buf, nframes);
        break;
    case SA_SAMPLE_FORMAT_S16:
        n = sf_readf_short(s, buf, nframes);
        break;
}

switch ( sa->format ) {
    case SA_SAMPLE_FORMAT_FLOAT:
        n = sf_writef_float(s, buf, nframes);
        break;
    case SA_SAMPLE_FORMAT_S16:
        n = sf_writef_short(s, buf, nframes);
        break;
}

// Turn off the PEAK chunk to ensure reproducible files
sf_command(s, SFC_SET_ADD_PEAK_CHUNK, NULL, SF_FALSE);