ffmpeg-split-audio - 色んなフォーマットの動画から音声を抽出

ffmpeg-split-audio

#!/bin/sh
#
# Original script from http://linuxos.blog102.fc2.com/blog-entry-131.html

QUIET=true

die() {
    echo "$@" >&2
    exit 1
}
ask() {
    msg="$1"
    default="$2"
    echo -n "$msg"
    # input
    read answer   || answer="$default"
    [ "$answer" ] || answer="$default"
    # check
    [ "$(echo "$answer" | sed 's/^y\(es\|eah\|ep\)\?.*//i')" = '' ]
}
do_ffmpeg() {
    input="$1"
    output="$2"
    if [ -e "$output" ] && ! ask "File '$output' already exists. Overwrite? [y/N] " 'N'; then
        echo "[skip] $output" >&2
        return 1
    fi
    if $QUIET; then
        ffmpeg -y -i "$input" -vn -acodec copy "$output" >/dev/null 2>/dev/null
    else
        ffmpeg -y -i "$input" -vn -acodec copy "$output"
    fi
    echo "[done] $output"
    return 0
}

while [ $# -ne 0 ]; do
    case "$1" in
        --) shift; break ;;
        -v|--verbose) QUIET=false ;;
        -*) die "error: unknown option '$1'" ;;
        *)  break ;;    # found non-option argument.
    esac
    shift
done

for arg; do
    noext="$(basename "$arg" | sed 's/\.[^.]\+$//')"
    ext="$(basename "$arg" | sed 's/.\+\.\([^.]\+\)$/\1/')"
    # no match -> empty string
    [ "$ext" = "$(basename "$arg")" ] && ext=
    # upper case -> lower case
    ext="$(echo "$ext" | tr '[:upper:]' '[:lower:]')"

    if [ "$ext" = "webm" ]; then
        # WebM
        do_ffmpeg "$arg" "$noext.ogg"
    elif [ "`file "$arg" --mime-type | grep x-flv`" ]; then
        # FLV
        do_ffmpeg "$arg" "$noext.mp3"
    elif [ "`file "$arg" --mime-type | grep mp4`" ]; then
        # MP4
        do_ffmpeg "$arg" "$noext.aac"
    elif [ "`file "$arg" --mime-type | grep asf`" ]; then
        # ASF
        do_ffmpeg "$arg" "$noext.wma"
    elif [ "`file "$arg" --mime-type | grep msvideo`" ]; then
        # MSVIDEO
        do_ffmpeg "$arg" "$noext.mp3"
    else
        echo "error: Couldn't find audio data: $arg" >&2
    fi
done