prints all best audio formats for a YouTube video (public domain)

audio_formats_list.sh

#!/bin/sh
# SPDX-License-Identifier: CC0-1.0 OR 0BSD
readonly POSIXLY_CORRECT
export POSIXLY_CORRECT

# this script generates a yt-dlp audio formats list for YouTube videos with multiple languages
# you can use this list like so, for example:
#   audio_formats_list="$(sh audio_formats_list.sh [url])"
#   yt-dlp --use-extractors youtube --audio-multistreams --format 'bestvideo'+"$audio_formats_list" -- [url]

# caveats:
# • all language tracks are labeled as English in merged file (maybe different in other locales?)
# • only works for YouTube
# • slow (but bearable)
# • tested, but not very thoroughly
# • dependencies (relatively commonplace, but not ideal)
# • hacky
# • the default audio track likely won’t be the default

url="$1"
export url

# if the audio format has a hyphen, that means there are multiple languages
if yt-dlp --simulate --use-extractors youtube --print format_id --format bestaudio -- "$url" | \
   grep --quiet --color=never --fixed-strings '-';then
   pre_format="$(yt-dlp --simulate --use-extractors youtube --print format_id --format bestaudio -- "$url")"
   format="${pre_format%-*}"
   export format
   pre_count="$(yt-dlp --simulate --use-extractors youtube --list-formats -- "$url"|grep --fixed-strings "$format"-|wc -l)"
   count="$((pre_count-2))"
   export count
   pre_formats="$(for i in $(seq 1 "$count");do printf '%s+' "$format"-"$i";done)"
   formats="${pre_formats%+}"
   printf '%s\n' "$formats"
# there isn’t a hyphen in this format, so just print this one format
else
   yt-dlp --simulate --use-extractors youtube --print format_id --format bestaudio -- "$url"
fi