youtube-download.sh

#!/usr/bin/env bash
set -euo pipefail

readonly RED='\033[0;31m'
readonly NC='\033[0m'

log() {
    echo "[$(date -u)] $*"
}

die() {
    echo -e "${RED}[$(date -u)] ERROR: $*${NC}" >&2
    exit 1
}

usage() {
    cat <<EOF
Script to download YouTube media (playlists or single videos) as MP3 (default) or video.
Usage:
    $(basename "$0") [-v|--video] <url_or_id> [dest_folder]
Options:
    -v, --video  Download best-quality video (mkv) instead of audio-only MP3
Arguments:
    url_or_id   - A full YouTube URL, a playlist ID, or a single video ID
    dest_folder - Where to store downloaded files (default: current directory)
EOF
    exit 1
}

MODE="audio"
TARGET=""
DEST=""

while [[ $# -gt 0 ]]; do
    case "$1" in
    -v | --video)
        MODE="video"
        shift
        ;;
    -h | --help)
        usage
        ;;
    -*)
        die "Unknown option $1"
        ;;
    *)
        if [[ -z "$TARGET" ]]; then
            TARGET="$1"
        elif [[ -z "$DEST" ]]; then
            DEST="$1"
        else
            die "Too many arguments provided"
        fi
        shift
        ;;
    esac
done

[[ -z "$TARGET" ]] && usage
DEST="${DEST:-$PWD}"

mkdir -p "$DEST" || die "Cannot create directory '$DEST'"
cd "$DEST" || die "Cannot switch to directory '$DEST'"

# Tool selection. Prefer yt-dlp over the largely unmaintained youtube-dl
if command -v yt-dlp &>/dev/null; then
    YOUTUBE_DL="yt-dlp"
    EXTRA_FLAGS=(--embed-metadata --concurrent-fragments 4)
elif command -v youtube-dl &>/dev/null; then
    YOUTUBE_DL="youtube-dl"
    EXTRA_FLAGS=(--add-metadata)
else
    die "Neither yt-dlp nor youtube-dl is installed"
fi

COMMON_FLAGS=(
    -4
    --retries 3
    --restrict-filenames
    --continue
    --no-progress
    --ignore-errors
    --embed-thumbnail
    --sleep-interval 5
    --download-archive "download-archive.txt"
    "${EXTRA_FLAGS[@]}"
)

log "Start downloading in $MODE mode"

if [[ "$MODE" == "audio" ]]; then
    "$YOUTUBE_DL" \
        "${COMMON_FLAGS[@]}" \
        --extract-audio \
        --audio-format mp3 \
        --audio-quality 0 \
        -o "%(artist,uploader|Unknown)s-%(track,title)s.%(ext)s" \
        "$TARGET"
else
    "$YOUTUBE_DL" \
        "${COMMON_FLAGS[@]}" \
        -f "bestvideo+bestaudio/best" \
        --merge-output-format mkv \
        --embed-subs \
        -o "%(title)s.%(ext)s" \
        "$TARGET"
fi

log "Download completed"