duration.lua

#!/usr/bin/env lua
-- prints the collected duration of all files listed on the command line or stdin

-- get filenames
if select("#", ...) == 0 then -- nothing on commandline, assume stdin
	files = {}
	while true do
		local s = io.stdin:read("*l")
		if not s or #s < 0 then break end -- read until ctrl+d or empty line
		table.insert(files, s)
	end
else
	files = {...}
end

local total = 0
for n=1,#files do
	local fname = files[n]
	if io.open(fname, "r") then -- if file exists
		local h, m, s = io.popen(("ffprobe %q 2>&1"):format(fname)):read("*a"):match("Duration: (%d%d):(%d%d):(%d%d)") -- disregard milliseconds
		total = total + h * 3600 + m * 60 + s
	end
end

h = math.floor(total / 3600)
m = math.floor((total - h * 3600) / 60)
s = total - h * 3600 - m * 60
io.stdout:write(("%02d:%02d:%02d"):format(h, m, s)) -- os.date was working with timezones and shit so I made my own shit for this