when a music request title not exist on the centovacast server, then download automatically and convert to mp3 with youtube-dl.

i have a way and it works, i installed youtube-dl,  check the unknown requests email with cron every minute and grep only {$request.song} in the email  > write in a requests.list
1 .Cron grep email for  {$request.song}

* * * * * </var/spool/mail/request sed -n -e "/<\!-- Begin/,/<\!-- End/ {/^<\!--/b;p;}" > /usr/local/centovacast/var/vhosts/x/var/spool/media/x/requests.list'

2 cron download from youtube

youtube-dl -o "%(title)s.%(ext)s" --extract-audio --audio-format mp3  --download-archive /usr/local/centovacast/var/vhosts/x/var/spool/media/requests/FILE --default-search "ytsearch" --batch-file='/usr/local/centovacast/var/vhosts/x/var/spool/media/requests/requests.list'

maybe there is a better solution.