A bash script to extract audio from a container.

extract_audio

#!/usr/bin/env bash

trap 'echo Ignoring' INT

get_codec_name() {
    ffprobe "$1" \
        -v quiet \
        -show_streams \
        -select_streams a \
        -show_entries stream=codec_name \
        | grep codec_name \
        | awk -F'=' '{ print $2 }' \
        || exit 1
}

ext_from_codec() {
    case "$1" in
        "aac")
            echo "m4a"
            ;;
        "vorbis")
            echo "ogg"
            ;;
        *)
            echo "$1"
            ;;
    esac
}

codec_name="$(get_codec_name "$1")"
ext="$(ext_from_codec "$codec_name")"

filename="$(basename -- "$1")"
filenameNoExt="${filename%.*}"

dir="$(dirname "$1")"
new="$dir/$filenameNoExt.$ext"

[[ -f "$new" ]] && exit 0

echo "Extracting audio for $1"
ffmpeg -hide_banner -v error -nostats -nostdin -i "$1" -c:a copy -x -o "$new" || exit 1
rm "$1"

Designed to be used in https://github.com/tytydraco/meow_dart. Pass in like this:

meow_dart ... -c ./extract_audio