FM Radio Audio Transmitter Script for Raserry Pi3B+. Requires working "pi_fm_adv". Supports: wav, mp3, m4a, ogg.

fm_transmit.sh

#!/bin/bash
# Author: Andreas Nilsen
# Email: [email protected]
# Github: https://www.github.com/adde88
# License: GPL-3

# Check arguments
if [[ $# -ne 2 ]]; then
    echo "Usage: $0 /path/to/file.{wav,mp3,m4a,ogg} frequency_in_MHz"
    echo "Example: $0 /home/pi/audio.mp3 100.1"
    exit 1
fi

# Input arguments
INPUT_FILE="$1"
FREQ="$2"

# Constants
PIFMADV_PATH="/root/PiFmAdv/src"
PIFM_EXEC="$PIFMADV_PATH/pi_fm_adv"
TMP_WAV="/tmp/tmp_fm_audio.wav"

# Check PiFmAdv binary
if [[ ! -f "$PIFM_EXEC" ]]; then
    echo "Error: pi_fm_adv not found at $PIFM_EXEC"
    exit 2
fi

# Check input file
if [[ ! -f "$INPUT_FILE" ]]; then
    echo "Error: Input file $INPUT_FILE not found"
    exit 3
fi

# Get file extension (lowercased)
EXT="${INPUT_FILE##*.}"
EXT="${EXT,,}"

# Handle file conversion if needed
case "$EXT" in
    wav)
        FINAL_FILE="$INPUT_FILE"
        ;;
    mp3|m4a|ogg)
        echo "[*] Converting $EXT to WAV..."
        ffmpeg -y -i "$INPUT_FILE" -ar 22050 -ac 1 "$TMP_WAV" >/dev/null 2>&1
        if [[ ! -f "$TMP_WAV" ]]; then
            echo "Error: Failed to convert to WAV."
            exit 4
        fi
        FINAL_FILE="$TMP_WAV"
        ;;
    *)
        echo "Error: Unsupported file format '$EXT'. Supported: wav, mp3, m4a, ogg"
        exit 5
        ;;
esac

# Transmit using PiFmAdv
echo "[*] Starting FM transmission on $FREQ MHz..."
sudo "$PIFM_EXEC" -f "$FREQ" -music "$FINAL_FILE"

# Cleanup if temporary file was used
if [[ "$FINAL_FILE" == "$TMP_WAV" ]]; then
    echo "[*] Cleaning up temporary WAV file..."
    rm -f "$TMP_WAV"
fi