splitmp3.sh

#!/usr/bin/env bash
# split a long mp3 into separate mp3s of equal length
# args: 
# <input_mp3>: filename of the long mp3
# <n_parts>: how many shorter mp3s you want to cut the long one into 
# ./splitmp3 long-mp3-audio.mp4 3 # -> gives you 3 output mp3s of equal length

if [ "$#" -ne 2 ]; then
    echo "Usage: $0 <input_mp3> <n_parts>"
    exit 1
fi

# Assign command line arguments to variables
input_mp3="$1"
n_parts="$2"

# Check if the file exists
if [ ! -f "$input_mp3" ]; then
    echo "File does not exist: $input_mp3"
    exit 1
fi

# Calculate the duration of the input file
duration=$(ffprobe -i "$input_mp3" -show_entries format=duration -v quiet -of csv="p=0")
if [ $? -ne 0 ]; then
    echo "Error determining file duration."
    exit 1
fi

# Calculate the duration of each part
part_duration=$(echo "$duration / $n_parts" | bc -l)

# Loop to split the file
for (( i=0; i<n_parts; i++ ))
do
    start_time=$(echo "$i * $part_duration" | bc)
    output_file=$(printf "%s_part%03d.mp3" "${input_mp3%.*}" $((i+1)))
    
    ffmpeg -i "$input_mp3" -ss "$start_time" -t "$part_duration" -acodec copy "$output_file"
    
    if [ $? -ne 0 ]; then
        echo "Error splitting file at part $((i+1))"
        exit 1
    fi
done

echo "Splitting complete."