Use yt-dlp instead of youtube-dl to resolve [YouTube download speed

limit](ytdl-org/youtube-dl#29326)

zsh/zshrc

@@ -124,8 +124,12 @@ command -v htop &>/dev/null          && alias top='sudo htop'
 command -v diff-so-fancy &>/dev/null && alias diff='diff-so-fancy'
 command -v ncdu &>/dev/null          && alias du='ncdu --color dark -rr -x'
 command -v tldr &>/dev/null          && alias help='tldr'
-command -v youtube-dl &>/dev/null    && alias youtube-dl="youtube-dl -f 'bestvideo[ext=mp4]+bestaudio[ext=m4a]' --write-sub --sub-lang 'zh-CN,zh-Hans,zh-TW,zh-Hant,en' --convert-subs 'srt' -o '%(uploader)s/%(playlist)s/%(playlist_index)03d.%(title)s.%(id)s.%(ext)s'"
 command -v jira &>/dev/null          && eval "$(jira --completion-script-bash)"
+if [ `command -v aria2c` ]; then
+  extargs="-ci --external-downloader aria2c --external-downloader-args '-s16 -x16 -k 4M' -f 'bestvideo[ext=mp4]+bestaudio[ext=m4a]' --write-sub --sub-lang 'zh-CN,zh-Hans,zh-TW,zh-Hant,en' --convert-subs 'srt' -o '%(uploader)s/%(playlist)s/%(playlist_index)03d.%(title)s.%(id)s.%(ext)s'"
+  command -v youtube-dl &>/dev/null && alias youtube-dl="youtube-dl $extargs"
+  command -v yt-dlp &>/dev/null && alias yt-dlp="yt-dlp $extargs"
+fi
 
 source "$ZDOTDIR/zsh-syntax-highlighting/zsh-syntax-highlighting.zsh"
 source "$ZDOTDIR/iterm2_shell_integration.zsh"