Script that downloads Youtube playlist and extracts the audio from the downloaded clips.

utpl_download.sh

#!/bin/bash

## URL
# The URL to the Youtube playlist
URL="http://www.youtube.com/playlist?list=PL60BA016CD6B147F8" 

## DESTPATH
# The path where to to download the music to
DESTPATH="$HOME/Music/awesome_new_music"

## TEMPDIR
# Directory for temporary videofiles
TEMPDIR="$DESTPATH/temp"

## CLEANUP
# Set to != 0 to remove temporary video files. If you don't clean the temp dir,
# ffmpeg will still extract audio from previously downloaded files.
CLEANUP=1

## PLAYLIST
# Filename for the local music playlist
PLAYLIST="playlist"

## UTIDLOG
# ID log for downloaded music files
UTIDLOG="downloaded.txt"

## TEMPLOG
# Temporary ID log for Youtube playlist
TEMPLOG="utplaylist.txt"

FFMPEG="/usr/bin/ffmpeg"        # Path to ffmpeg
YOUTUBEDL="/usr/bin/youtube-dl" # Path to youtube-dl
#########

set -e
IFS="`printf '\n\t'`"

echo "YouTube playlist downloader"
echo "---------------------------"

# Check parameters
if [ "$1" == "help" ]; then
    cat <<EOF
This script downloads videos from a Youtube playlist and
converts them to audio. It keeps track of what tracks have
already been downloaded before.

usage: `basename $0` [URL] [destpath]
usage: `basename $0` help

     URL : playlist url
destpath : the destination path where to download the playlist
    help : prints this help
EOF
    exit 0
fi
[[ $# -gt 0 ]] && URL="$1"
[[ $# -gt 1 ]] && DESTPATH="$2"

# Create directories and files
if [ ! -d "$DESTPATH" ]; then
    mkdir -p "$DESTPATH"
fi
if [ ! -d "$TEMPDIR" ]; then
    mkdir -p "$TEMPDIR"
fi

for I in "$PLAYLIST" "$UTIDLOG" "$TEMPLOG"; do
    if [ ! -f "$DESTPATH/$I" ]; then
        touch "$DESTPATH/$I"
    fi
done

cat <<EOF

Playlist:    $URL
Destination: $DESTPATH

EOF

echo "Fetching playlist IDs... (this might take a while)"
# Indeed this is very slow. It'd be better to fetch the playlist info from
# YouTube API and parse the IDs from there. I'll fix this someday...
$YOUTUBEDL -s --get-filename "$URL" | cut -d"." -f 1 > "$DESTPATH/$TEMPLOG"

echo "Downloading videos..."
while read utid; do
    if ! grep "^$utid" "$DESTPATH/$UTIDLOG" > /dev/null; then
        $YOUTUBEDL -c -o "$TEMPDIR/%(stitle)s.%(ext)s" "$utid"
    fi
done < "$DESTPATH/$TEMPLOG"

echo "Extracting the audio..."
for f in "$TEMPDIR/"*; do
    if [ -e "$f" ]; then
        # FFMpeg pretty much just extracts the audio track to a separate file.
        # In some cases, it might be more wise to extract AND encode the audio.
        fformat=$($FFMPEG -i "$f" 2>&1 | sed -n "s/\s*Stream .*: Audio: \([a-zA-Z0-9]\+\),.*/\1/p")
        inname=`basename $f`
        outname="${inname%.*}.$fformat"
        #outname="${inname%.*}" # Alternative output filename
        $FFMPEG -y -i "$f" -acodec copy "$DESTPATH/$outname"
        #$FFMPEG -y -i "$f" -ab 192k "$DESTPATH/$outname.mp3" # Alternative way to extract audio
    fi
done

# YouTube playlist -> downloaded
if [ -s "$DESTPATH/$TEMPLOG" ]; then
    mv "$DESTPATH/$TEMPLOG" "$DESTPATH/$UTIDLOG"
else
    rm -f "$DESTPATH/$TEMPLOG"
fi

# Create playlist
# Listed enough formats just to be sure.
find "$DESTPATH" -type f \( \
    -iname "*.mp3" -o \
    -iname "*.ogg" -o \
    -iname "*.aac" -o \
    -iname "*.flac" \) \
    -printf "%f\n" > "$DESTPATH/$PLAYLIST"

if [ ! $CLEANUP -eq 0 ]; then
    echo "Cleaning up temporary files..."
    for f in "$TEMPDIR/"*; do
        if [ -e "$f" ]; then
            rm -fv "$f"
        fi
    done
fi