hi all .
i have a pine64+ and install dietpi .
it runs well and i watch youtube very smoothly and sound comes from TV .
my install memo is the folowings
A) dietpi-config
advanced option —> swap : 1024M
B) dietpi-software
—> Software optimized
—> lxde chromium
—> desktop
—> install
C) adduser pi
cat .xinitrc → startlxde
D) /etc/default/keyboard
E) dpkg-reconfigure tzdata
dpkg-reconfigure locales
do not get rid of en_GB.UTF-8
F) apt-get install aptitude
G) japanese
aptitude install fonts-takao-gothic
aptitude install scim-anthy im-config zenity
H) aptitude install slim
nano /etc/slim.conf
youtube is very smooth : sea —> https://www.youtube.com/watch?v=WemrIZSTqUc
thanks 
