ffmpeg script to pad the start of an audio file with silence for a 1h total

pad-audio-1h

#!/bin/bash

output_folder="padded_audio"
mkdir -p "$output_folder"

# Function to pad audio file and preserve metadata
function pad_audio() {
    input_file=$1
    duration=$(ffprobe -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 "$input_file")
    if (( $(bc <<< "$duration < 3600") )); then
        pad_duration=$(bc <<< "3600 - $duration")
        output_file="$output_folder/padded_$input_file"
        ffmpeg -i "$input_file" -f lavfi -i "aevalsrc=0:d=${pad_duration}" -filter_complex "[1:a][0:a]concat=n=2:v=0:a=1[a]" -map 0:v -map "[a]" -map_metadata 0 "$output_file"
    else
        echo "File $input_file is already one hour or longer. Skipping."
    fi
}

# Process audio files one by one
for file in *.mp3; do
    pad_audio "$file"
done

echo "Padding process completed."