ffmpeg_extract_audio_from_video.sh - Extracts audio from video files by running ffmpeg

ffmpeg_extract_audio_from_video.sh

#!/bin/bash
DEFAULT_OUTPUT_FOLDER="out-audio-files"
if [ $# -lt 1 ]; then
    echo "[-] $0 <folder/file-to-get-audio-from> [out-folder]"
    echo
    echo "Description: "
    echo "This script converts a single file and outputs the file into an output folder"
    echo "This script has been written for MacOS X only"
    echo
    echo "Arguments:"
    echo "folder/file-to-get-audio-from: File/folder which is a video file to get audio from"
    echo "out-folder: Output folder to write multiple files to. Only valid if folder was specified with files for conversion" 
    echo
    exit
fi
in_file_folder="$1"
out_folder="$2"

[ -z "$out_folder" ] && out_folder="$DEFAULT_OUTPUT_FOLDER"
echo "[+] out_folder: $out_folder"

function install {
    # Install ffmpeg dependency via brew
    echo "[*] Installing ffmpeg"
    brew install ffmpeg
}

function get_audio_filename_from_video_filename {
    in_file="$1"

    in_file_ext="${in_file##*.}"
    in_file_name_without_ext="${in_file%.*}"
    out_file="$in_file_name_without_ext.mp3"
    echo "$out_file"
}

function convert_single_video_file_to_audio {
    in_file="$1"
    out_file="$2"

    echo "[*] Converting input video file: $in_file to mp3 output file: $out_file using ffmpeg"
    ffmpeg -i "$in_file"  -q:a 0 -map a "$out_file"
}

if [ -f "$in_file_folder" ]; then
    in_file="$in_file_folder"

    out_file=$(get_audio_filename_from_video_filename "$in_file")
    convert_single_video_file_to_audio "$in_file" "$out_file"

elif [ -d "$in_file_folder" ]; then
    in_folder="$in_file_folder"
    
    if [ ! -d "$out_folder" ]; then
        echo "[*] Making output folder: $out_folder"
        mkdir "$out_folder"
    fi
    
    in_files=`ls -1 "$in_folder"`
    IFS=$'\n'
    for in_file in `echo "$in_files"`; do
        out_file=$(get_audio_filename_from_video_filename "$in_folder/$in_file")
        convert_single_video_file_to_audio "$in_folder/$in_file" "$out_file"
        mv "$out_file" "$out_folder"
    done
else
    echo "[-] Non-existant file/folder: $in_file_folder"
    exit
fi