Extract audios of the videos in a given playlist using yt-dlp and GNU parallel.

download.sh

#!/bin/bash

function print_help_message() {
    echo "Extracts audios from the videos in a given playlist using yt-dlp and GNU parallel"
    echo
    echo "USAGE: ${0} [options] <playlist_id>"
    echo
    echo "OPTIONS:"
    echo "-h, --help            Print this message."
    echo "-o, --output DIR      Download videos to DIR"
    echo "-i, --ignore FILE     Ignore the IDs in FILE"
    echo "-s, --save FILE       Save the IDs of the downloaded videos into FILE"
}

# Extracts the audio of a given video (id) as an mp3 file.
function extract_audio() {
    yt-dlp \
        -q \
        --concurrent-fragments 4 \
        -x \
        --audio-quality 0 \
        --audio-format mp3 \
        -o "%(title)s.%(ext)s" \
        -P ${1} \
        ${2}
    }

# Export the function so that it can be passed to `parallel`.
export -f extract_audio

OUTPUT=$(pwd)
POSITIONAL_ARGS=()

while [[ $# -gt 0 ]]; do
    case $1 in
        -h|--help)
            print_help_message
            shift
            exit 0
            ;;
        -o|--output)
            OUTPUT="$2"
            shift
            shift
            ;;
        -i|--ignore)
            IGNORE="$2"
            shift
            shift
            ;;
        -s|--save)
            SAVE="$2"
            shift
            shift
            ;;
        -*|--*)
            echo "Unknown option: $1"
            exit 1
            ;;
        *)
            POSITIONAL_ARGS+=("$1")
            shift
            ;;
    esac
done

set -- "${POSITIONAL_ARGS[@]}"

if [ -z "$1" ]
then
    echo "No playlist id specified"
    exit 1
fi

# Extract the ids of all the videos in the playlist
ID_LIST=$(yt-dlp --flat-playlist --get-id ${1} | sort)

if [ -n "$IGNORE" ]
then 
    if [ -e "$IGNORE" ]
    then 
        # Filter ids that appear in the ignore file
        ID_LIST=$(echo "$ID_LIST" | comm -23 - <(sort $IGNORE))
    else
        echo "File not found: \"$IGNORE\", continuing without the ignore file"
    fi
fi

# Count the number of ids, ignore empty lines.
TOTAL=$(echo "$ID_LIST" | awk "NF" | wc -l)

if [[ $TOTAL -ne 0 ]]
then
    echo "Downloading $TOTAL video(s)..."

    # Extract audios of the videos using parallel and display a progress bar.
    echo "$ID_LIST" | parallel --bar extract_audio $OUTPUT

    # Store the ids if specified
    if [ -n "$SAVE" ]
    then
        echo "$ID_LIST" >> "$SAVE"
    fi
else
    echo "No videos to download"
fi