soundstretch.sh

#!/bin/bash
#
# Brain hacking in action: A simple bash script for making "fast" versions of mp3 files.
# 
# Usage: The script takes 2 arguments, a "getdir" and a "putdir".
#
# The script will recursively search for mp3 files in getdir and make "fast" versions of them
# (+40% speed). The full directory tree (from /) is recreated inside putdir, and the
# fast mp3s are placed in their corresponding locations in the new tree.
#
# Dependencies:
# * lame
# * soundstretch
# * id3lib

FORCE=0
VERBOSE=0
while getopts ":fv" opt; do
	case $opt in
		f)
			FORCE=1
			;;
		v)
			VERBOSE=1
			;;
		\?)
			echo "Invalid option: $OPTARG"
			echo "Usage: `basename $0` [-fv] getdir putdir"
			exit 1 
			;;
	esac
done

echo "---------------"

shift $((OPTIND-1))

if [[ ! -n "$1" || ! -n "$2" ]] ; then
	echo "Usage: `basename $0` [-fv] getdir putdir"
	exit 1
fi

DEPENDENCIES="lame soundstretch id3cp"
for i in $DEPENDENCIES ; do
	type $i >/dev/null 2>&1 || { echo >&2 "Error: Required dependency $i not installed."; exit 1; }
done

GETDIR=$1
PUTDIR=$2

convertFile () {
	force=$3
	verbose=$4
	file="$1"
	if [ $verbose -eq 0 ]; then
    	exec &>/dev/null
	fi
	echo "Now processing: $file"
	if [[ "${1:0:2}" == './' ]] ; then
		file="${file:2}"
	fi
	base=${file%.*}
	if [[ "${base:0:1}" != '/' ]] ; then
		base="$(pwd)/$base"
	fi
	basedir=${base%/*}
	ext=${file#*.}
	outdir="$2"
	if [[ -e "$outdir/$base.fast.mp3" ]] ; then
		if [[ $force -eq 0 ]] ; then
			echo "File exists. Will not overwrite."
			exit 1
		else
			echo "File exists. Overwriting."
		fi
	fi
	mkdir -p "$outdir/${basedir}"
	lame --decode "$file" "$base.wav"
	soundstretch "$base.wav" "$base.fast.wav" -tempo=+40
	lame --preset fast medium "$base.fast.wav" "$outdir/$base.fast.mp3"
	id3cp "$file" "$outdir/$base.fast.mp3"
	rm "$base.wav" "$base.fast.wav"
	echo "---------------"
}

export PUTDIR="$PUTDIR"
export FORCE=$FORCE
export VERBOSE=$VERBOSE
export -f convertFile

find "$GETDIR" -type f \( -iname "*.mp3" -a ! -iname "*.fast.mp3" \) -exec bash -c 'convertFile "{}" "$PUTDIR" $FORCE $VERBOSE' ';'

exit 0