Awesome

This script will update a xfce4-panel genmon plugin that is set up with genmonify to display the currently playing media file and elpapsed or remaining time.

Example settings (~/.config/mpv/scrip-opts/xfce-genmonify.conf):

pause_color=#EEEEEE
icon_click_command="mediacontrol toggle"
icon_playing=mpv
icon_paused=media-playback-start
time_remaining=yes

Setting up the genmonify thing:

install genmon and genmonify
add a genmon instance, max out the time and set the command to genmonify -o media
find the internal xfce-panel ID for the genmon instance (genmonify --list)
add the line modules[media]=ID to ~/.config/genmonify/module-list

mpv-genmonify