An "opener" script.

o.sh

#!/bin/bash

audio_viewer="nvlc"
image_viewer="eog"
pdf_viewer="zathura"
video_viewer="nvlc"

set -eu

if [[ $# -ne 1 ]]; then
	echo "Usage: o <FILE>" >&2
	exit 1
fi

mime="$(xdg-mime query filetype "$1")"
case "$mime,$1" in
	application/pdf,*)
		viewer="$pdf_viewer"
		;;
	audio/*,*)
		viewer="$audio_viewer"
		;;
	image/*,*)
		viewer="$image_viewer"
		;;
	text/xml,*.xspf)
		viewer="$audio_viewer"
		;;
	video/*,*)
		viewer="$video_viewer"
		;;
	*)
		echo "Unknown file type: $mime" >&2
		exit 1
		;;
esac

$viewer "$1" 2>/dev/null