Given an audio file, break it into chunks

audio-splitter.sh

#!/bin/bash

# Copyright (c) 2013, Tyndyll
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#	 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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function convert() {
    $FFMPEG -i "$1" -ss $3 -t $4 $FFMPEG_OPTIONS "$2.$TYPE"
}

function help() {
    echo "`basename $0` [options] <podcast_file>
    
-c    Clobber an existing output directory. Allow podcast parts to be overwritten
-f    Options to be passed to FFMPEG (default: $FFMPEG_OPTIONS)
-h    Print this help file
-l    Define the length in seconds into which parts should be cut into (default: $CHUNKLENGTH)
-m    Output as MP3
-o    Output directory
    
    " 1>&2
    exit 2;
}

declare -i CHUNKLENGTH=300
FFMPEG_OPTIONS="-ar 44100 -loglevel error"
CLOBBER=0
OUTPUT=
TYPE=wav

while getopts ":cf:hl:mo:" opt; do
    case "${opt}" in
	c)
	    CLOBBER=1
	    ;;
	f)
	    FFMPEG_OPTIONS=$OPTARG
	    ;;
	h)
	    help
	    ;;
    l)
        CHUNKLENGTH=$OPTARG
        if [[ $CHUNKLENGTH -eq 0 || $CHUNKLENGTH -gt 600 ]]; then
            echo "Part length must be a number lower than 600" 1>&2
            exit 2
        fi
        ;;
	m)
	    TYPE=mp3
	    ;;
	o)
	    BASENAME=$OPTARG
	    ;;
	u)
	    URL=$OPTARG
	    ;;
    *)
	    echo "Invalid option: -$OPTARG" >&2
	    help
	    ;;
    esac
done
shift $((OPTIND-1))

FFMPEG=`which ffmpeg`
if [ $? -ne 0 ]; then
    echo "Cannot find ffmpeg. Exiting"
    exit 127
fi

MP3INFO=`which mp3info`
if [ $? -ne 0 ]; then
    echo "Cannot find mp3info. Exiting"
    exit 127
fi

INPUTFILE=$1
if [ ! -e "$INPUTFILE" ]; then
    echo "Cannot find input file. Exiting"
    help
fi

if [[ -z $BASENAME ]]; then
    BASENAME=`basename "$1" | sed -e 's/\.mp3$//'`
fi

if [[ -e "$BASENAME" ]]; then
    if [[ $CLOBBER -eq 0 ]]; then
        echo "Cannot output to $BASENAME. Directory exists. Exiting"
        exit 3
    fi
else
    mkdir "$BASENAME"
fi

FFMPEG_OPTIONS="-y $FFMPEG_OPTIONS"
declare -i TOTALTIME=`$MP3INFO -p "%S" "$1"`
if [[ $? -ne 0 || $TOTALTIME -le 0 ]]; then
    echo "Cannot determine overall file length. Exiting"
    exit 3
fi

declare -i POS=0
declare -i PART=1
while [[ $TOTALTIME -gt 0 ]]; do
    OUTPUTFILE=`printf "%s/%s%02d" "$BASENAME" "$BASENAME" $PART`
    if [[ $TOTALTIME -lt $CHUNKLENGTH ]]; then
        CHUNKLENGTH=$TOTALTIME
    fi
    echo "Converting part $PART, from $POS for $CHUNKLENGTH seconds"
    convert "$1" "$OUTPUTFILE" $POS $CHUNKLENGTH
    POS+=$CHUNKLENGTH
    PART+=1
    TOTALTIME=$(($TOTALTIME-$CHUNKLENGTH))
done