How can I show/display volume level from youtube video OR local media without reading it yet.
Idea is when that information is known to make a play of a file list, or better of read my full "read later" youtube playlist without changing permanantly the sound level.
BUT I want here a scripted solution as far as I want that to be also available for my local files.
something like :

So the real question here is : how to get metadata or evaluation of recoreded sound level from any media ?
what I tryied and abandonned :
- mstpy solutions - failed on to many medias & doesn't really fit my needs when it works
- vlc & audacity tuning sound level can only be regulated on local files list
- SoundFixer by unrelenting.technology but works only on FEW web sites
- a script base on
mkfifo /tmp/mi{1,2} URL1=......... URL2=......... mplayer -softvol
-slave -input file=/tmp/mi1 $url1 &>/dev/null & mplayer -softvol -slave -input file=/tmp/mi2 $url2 & for ((i=1; i<=100; i+=1)); do sleep 0.25; echo "volume $(( 100 - $i )) 1 ">/tmp/mi1; sleep 0.25 ;
echo "volume $i 1 ">/tmp/mi2 ; done ; (sleep 5 ; echo quit >/tmp/mi1
;echo quit >/tmp/mi2)&
NOTA : I don't want to install too musch things to avoid having issues on already install applications & media players.
If there is a mplayer/mencoder solution that might be the very better solution.