Re: mass conversion from ogg to mp3

[Stefan Monnier <monnier@iro.umontreal.ca>]

> I have a large number of music files (17 gig worth...yes, for all prying
> eyes they are legal...) that I find I need to convert from .ogg to .mp3.

> Not that I want to...but between a teenager with an iphone and being saddled
> with cell phone that won't play .ogg...well, you get the picture.

> What is the best way to do this?  I would prefer a CLI option that I can run
> in the background, but I want to save as much sound quality as I can with
> the transfer...

You may want to consider this conversion, not as a way to replace your
Ogg collection with an MP3 collection, but just as a way to get
a specialized version of your collection for some particular devices.

My main collection is in Flac format, but I convert it to Ogg(96kb/s)
before uploading it to my "MP3" player, since Flac would take up too
much space.  The quality is not as high, but given the circumstances in
which I listen to it, I can't really tell the difference.

As for the conversion, I use the script below.


        Stefan


#!/bin/sh

bitrate="bitrate=98304"         # 96Kb/s
samplerate=""
delete=false
dontrun=false
outformat=ogg

if [  -x "/usr/bin/gst-launch-0.10" ]; then
    gst_launch="/usr/bin/gst-launch-0.10"
    resample="audioresample !"
    decode="decodebin"
    oggmux="! oggmux"
else
    gst_launch="gst-launch-0.8"
    resample="audioscale !"
    decode="spider"
    oggmux=""
fi

usage () {
    echo "usage: $(basename $0) [--bitrate=KBITS] [--samplerate=HZ] [--delete] FROM [TO]"
}

while [ $# -gt 0 ]; do
    case "$1" in
        --bitrate=*) bitrate="bitrate=$(expr "$(echo "$1" | sed 's/.*=//')" "*" 1024)";;
        --quality=*) bitrate="quality=$(echo "$1" | sed 's/.*=//')";;
        --samplerate=*)
          rate=$(echo $1 | sed 's/.*=//')
          samplerate="$resample audio/x-raw-int,rate=$rate !" ;;
        --help) usage; exit 0 ;;
        --delete) delete=true ;;
        --flac) outformat=flac ;;
        -n ) dontrun=true ;;
        -*) usage ; exit 1 ;;
        *)  from="$1"; to="$2"; if [ $# -gt 1 ]; then shift; fi ;;
    esac
    shift
done

case "$outformat" in
    ogg )
        fileext="64.ogg"
        encoder="vorbisenc $bitrate $oggmux"
        ;;
    flac )
        fileext="flac"
        case "$bitrate" in
            quality=* ) ;;
            * ) bitrate="" ;;
        esac
        encoder="flacenc $bitrate"
        ;;
esac

if [ "$from" = "" ]; then
    usage; exit 1
fi

run () {
    echo "$@"
    if [ "$dontrun" = "false" ]; then
        "$@"
    fi
}

convertfile() {
    from="$1"
    to="$2"

    if [ "$to" = "" ]; then
        to="."
    fi
    
    if [ -d "$to" ]; then
        case "$from" in
            /* ) fromrel="$(basename $from)" ;;
            * )  fromrel="$from"
        esac
        base="$(echo "$fromrel" | sed 's/\.[^.][^.]*$//')"
        to="$to/$base.$fileext"
    fi
    
    if [ "$to" = "$from" ]; then
        echo "Don't know how to overwrite!"
        exit 1
    fi
    echo "Converting "'"'"$from"'"'" to "'"'"$to"'"'
    # "gst-inspect vorbisenc" shows available options
    #
    # FIXME! The stupid flacenc/flacdec/audioconvert step works around
    # a problem I found when converting Ogg files that had been split by
    # mp3splt (in which case, oggmux seems to get confused and outputs an
    # empty file).
    run $gst_launch filesrc location="$from" ! $decode ! $samplerate audioconvert ! $encoder ! filesink location="$to"
    if [ "$?" = "0" ] && [ "$delete" = "true" ]; then
        run rm "$from"
    fi
}

convert () {
    case "$1" in
        *."$fileext" ) ;;           # Nothing to do.
        * )
            if [ -d "$1" ]; then
                case $1 in */) from="$1" ;; *) from="$1/" ;; esac
                for f in "$from"*.ogg \
                    "$from"*.flac \
                    "$from"*.m4a \
                    "$from"*.mp3 \
                    "$from"*.ac3 \
                    "$from"*.wav \
                    "$from"*/;
                do
                    if [ -r "$f" ]; then
                        convert "$f" "$2"
                    fi
                done
            else
                convertfile "$1" "$2"
            fi
    esac
}

convert "$from" "$to"

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