excerpt.lua

-- This script allows to create excerpts of a video that is played,
-- press "i" to mark the begin of the range to excerpt,
-- press "o" to mark the end   of the range to excerpt,
-- press "I" to continue playback at the "begin" location,
-- press "O" to jump to the "end" location and pause there,
-- press "x" to actually start the creation of the excerpt,
--  which will be done by starting an external executable
--  named "excerpt_copy" with the parameters $1 = begin,
--  $2 = duration, $3 = source file name
-- (see bottom of this file for all key bindings)

-- script options: Use...
--
--   --script-opts=excerpt-source-based-filename=1
--      to make excerpt.lua use the source filename as
--      a base for the destination filename for excerpts
--   --script-opts=excerpt-source-based-extension=1
--      to make excerpt.lua use the same filname extension
--      for destination files than that of the source file -
--      without this option, the extension ".mp4" will be used.
--      Notice that unlike specified otherwise in "excerpt_copy",
--      the filename extension will determine the format of the output.
--
-- (--script-opts can parse multiple options as comma-separated key-value pairs.)

-- initialization:

utils = require 'mp.utils'

excerpt_begin = 0.0
excerpt_end   = mp.get_property_native("length")
if excerpt_end == nil or excerpt_end == "none" then
 excerpt_end = 0.0
end


mp.set_property("hr-seek-framedrop","no")
mp.set_property("options/keep-open","always")

-- alas, the following setting seems to not take effect - needs
-- to be specified on the command line of mpv, instead:
-- mp.set_property("options/script-opts","osc-layout=bottombar,osc-hidetimeout=120000")


function excerpt_on_eof()
	-- pause upon reaching the end of the file
	mp.msg.log("info", "playback reached end of file")
	mp.set_property("pause","yes")
	mp.commandv("seek", 100, "absolute-percent", "exact")
end
mp.register_event("eof-reached", excerpt_on_eof)

-- range marking

function excerpt_rangemessage() 
	local duration = excerpt_end - excerpt_begin
	local message = ""
	message = message .. "begin=" .. string.format("%4.3f", excerpt_begin) .. "s "
	message = message .. "end=" .. string.format("%4.3f", excerpt_end) .. "s "
	message = message .. "duration=" .. string.format("% 4.3f", duration) .. "s "
	return message
end

function excerpt_rangeinfo() 
	local message = excerpt_rangemessage()
	mp.msg.log("info", message)
	mp.osd_message(message, 5)
end

function excerpt_mark_begin_handler() 
	pt = mp.get_property_native("playback-time")
	if pt == nil or pt == "none" then
		pt = 0.0
	end
 	
	-- at some later time, setting a/b markers might be used to visualize begin/end
	-- mp.set_property("ab-loop-a", pt)
	-- mp.set_property("loop", 999)
 
	excerpt_begin = pt
	if excerpt_begin > excerpt_end then
		excerpt_end = excerpt_begin
	end
 
	excerpt_rangeinfo()
end

function excerpt_mark_end_handler() 
	pt = mp.get_property_native("playback-time")
	if pt == nil or pt == "none" then
		pt = 0.0
	end

	-- at some later time, setting a/b markers might be used to visualize begin/end
	-- mp.set_property("ab-loop-b", pt)
	-- mp.set_property("loop", 999)
  
	excerpt_end = pt
	if excerpt_end < excerpt_begin then
		excerpt_begin = excerpt_end
	end

	excerpt_rangeinfo()
end

-- writing

function get_destination_filename()

	local sbf = tonumber(mp.get_opt("excerpt-source-based-filename"))
   if (sbf == nil) then
		sbf = 0
	end
	
	local sbe = tonumber(mp.get_opt("excerpt-source-based-extension"))
   if sbe == nil then
		sbe = 0
	end
	
	local srcname   = mp.get_property_native("filename")
	local srcnamene = mp.get_property_native("filename/no-ext")
	
	local ext_length = string.len(srcname) - string.len(srcnamene)
	local srcext     = string.sub(srcname, -ext_length)
	
	local dstext = ".mp4"
	if sbe == 1 then
		-- use same filename extension than input
		dstext = srcext
	end
	
	local dstname

	if sbf == 1 then
		dstname = srcnamene .. ".excerpt_" .. excerpt_begin .. "-" .. excerpt_end
	else
		-- create a new, unique filename by scanning the current
		-- directory for non-existence of files named "excerpt_$number.$extension"

		local cwd = utils.getcwd()
		local direntries = utils.readdir(cwd)
		local ftable = {}
		for i = 1, #direntries do
			-- mp.msg.log("info", "direntries[" .. i .. "] = " .. direntries[i])
			ftable[direntries[i]] = 1
		end 
		
		local fname = ""
		for i=0,999 do
			local f = string.format("excerpt_%03d", i)
			-- mp.msg.log("info", "ftable[" .. f .. dstext .. "] = " .. direntries[f .. dstext])
			
			if ftable[f .. dstext] == nil then
				fname = f
				break
			end
 		end
		if fname == "" then
			message = "not writing because all filenames already in use" 
			mp.osd_message(message, 10)
			return ""
		end
		dstname = fname
	end
	
	return dstname .. dstext
end


function excerpt_write_handler() 
	if excerpt_begin == excerpt_end then
		message = "excerpt_write: not writing because begin == end == " .. excerpt_begin
		mp.osd_message(message, 3)
		return
	end
 	
	dstname = get_destination_filename()
	if (dstname == "") then
		-- file name creation has failed
		return
	end
	
	duration = excerpt_end - excerpt_begin
	
	local srcname = mp.get_property_native("path")
	
	local message = excerpt_rangemessage()
	message = message .. "writing excerpt of source file '" .. srcname .. "'\n"
	message = message .. "to destination file '" .. dstname .. "'" 
	mp.msg.log("info", message)
	mp.osd_message(message, 10)
 
	local p = {}
	p["cancellable"] = false
	p["args"] = {}
	p["args"][1] = "excerpt_copy"
	p["args"][2] = tostring(excerpt_begin)
	p["args"][3] = tostring(duration)
	p["args"][4] = tostring(srcname)
	p["args"][5] = tostring(dstname)
	
	local res = utils.subprocess(p)
	
	if (res["status"] ~= 0) then
		message = message .. "failed!\nfailed to run excerpt_copy - status = " .. res["status"]
		if (res["error"] ~= nil) then
			message = message .. ", error message: " .. res["error"]
		end
		message = message .. "\nstdout = " .. res["stdout"]
		mp.msg.log("error", message)
		mp.osd_message(message, 10)
	else
		mp.msg.log("info", "excerpt '" .. dstname .. "' written.")
		message = message .. "... done."
		mp.osd_message(message, 10)
	end
 
end

-- assume some plausible frame time until property "fps" is set.
frame_time = 24.0 / 1001.0

function excerpt_fps_changed(name)
	ft = mp.get_property_native("fps")
	if ft ~= nil and ft > 0.0 then
		frame_time = 1.0 / ft
		-- mp.msg.log("info", "fps property changed to " .. ft .. " frame_time=" .. frame_time .. "s")
	end
end
mp.observe_property("fps", native, excerpt_fps_changed)

-- seeking

seek_account = 0.0
seek_keyframe = true

function excerpt_seek()
		
	local abs_sa = math.abs(seek_account)
	if abs_sa < (frame_time / 2.0) then
		seek_account = 0.0
		-- no seek required		
		return
	end
	
	-- mp.msg.log("info", "seek_account = " .. seek_account)
	
	if (abs_sa >= 10.0) then
		-- for seeks above 10 seconds, always use coarse keyframe seek
		local s = seek_account
		seek_account = 0.0
		mp.commandv("seek", s, "relative+keyframes")
		return
	end

	if ((abs_sa > 0.5) or seek_keyframe) then
		-- for small seeks, use exact seek (unless instructed otherwise by user)
		local s = seek_account
		seek_account = 0.0
		
		local mode = "relative+exact"
		if seek_keyframe then
			mode = "relative+keyframes"
		end
		
		mp.commandv("seek", s, mode)
		return
	end
	
	-- for tiny seeks, use frame steps
	local s = frame_time
	if (seek_account < 0.0) then
		s = -s
		mp.commandv("frame_back_step")
	else
		mp.commandv("frame_step")
	end
	seek_account = seek_account - s;
end

-- we have excerpt_seek called both periodically and 
-- upon the display of yet another frame - this allows
-- to make "framewise" stepping with autorepeating keys to 
-- work as smooth as possible
excerpt_seek_timer = mp.add_periodic_timer(0.1, excerpt_seek)
mp.register_event("tick", excerpt_seek)
-- (I have experimented with stopping the timer when possible,
--  but this didn't work out for strange reasons, got error
--  messages from the event loop.)


function check_key_release(kevent)
	-- mp.msg.log("info", tostring(kevent))
	-- for k,v in pairs(kevent) do
	-- 	mp.msg.log("info", "kevent[" .. k .. "] = " .. tostring(v))
	-- end
	
	if kevent["event"] == "up" then
		-- mp.msg.log("info", "key up detected")
		
		-- key was released, so we should immediately stop to do any seeking
		seek_account = 0.0
		
		-- The "zero-seek" at key-release seems to do more harm than good with recent mpv versions:
		--  if mpv has not reached the new position from the previously issued seek yet and a relative seek to 0.0 is done, this
		--  will counter-act the idea of doing a coarse key-frame seek, causing a long wait
		--  before an image is shown for the new position.
		-- So for no, we do not perform this "zero-seek".
		if false then
		if (not seek_keyframe) then
			-- and do a "zero-seek" to reset mpv's internal frame step counter:
			mp.commandv("seek", 0.0, "relative", "exact")
			mp.set_property("pause","yes")
		end
		end
		return true
	end
	return false
end
	
function excerpt_frame_forward(kevent)
	if check_key_release(kevent) then
		return
	end
	
	seek_keyframe = false
	seek_account = seek_account + frame_time	
end

function excerpt_frame_back(kevent)
	if check_key_release(kevent) then
		return
	end
	
	seek_keyframe = false
	seek_account = seek_account - frame_time
end

function excerpt_keyframe_forward(kevent)
	if check_key_release(kevent) then
		return
	end
	
	seek_keyframe = true
	seek_account = seek_account + 0.4
end

function excerpt_keyframe_back(kevent)
	if check_key_release(kevent) then
		return
	end
	
	seek_keyframe = true
	seek_account = seek_account - 0.6
end

function excerpt_seek_begin_handler() 
	mp.commandv("seek", excerpt_begin, "absolute", "exact")
end

function excerpt_seek_end_handler() 
	mp.commandv("seek", excerpt_end, "absolute", "exact")
end

-- zooming and panning

excerpt_zoom = 0.0
excerpt_zoom_increment_factor = 2 ^ 0.25

excerpt_pan_x = 0.0
excerpt_pan_y = 0.0

function excerpt_set_pan()
	local max_pan = 0.5 - (1.0 / ((excerpt_zoom+1.0)*2.0))
	
	if (excerpt_pan_x < -max_pan) then
		excerpt_pan_x = -max_pan
	end

	if (excerpt_pan_x > max_pan) then
		excerpt_pan_x = max_pan
	end
	
	if (excerpt_pan_y < -max_pan) then
		excerpt_pan_y = -max_pan
	end
	
	if (excerpt_pan_y > max_pan) then
		excerpt_pan_y = max_pan
	end
	
	mp.set_property("video-pan-x", excerpt_pan_x)	 
	mp.set_property("video-pan-y", excerpt_pan_y)	 
end

function excerpt_pan_right()
	excerpt_pan_x = excerpt_pan_x - (1.0 / (16*(excerpt_zoom+1.0)))
	excerpt_set_pan()
end

function excerpt_pan_left()
	excerpt_pan_x = excerpt_pan_x + (1.0 / (16*(excerpt_zoom+1.0)))
	excerpt_set_pan()
end

function excerpt_pan_down()
	excerpt_pan_y = excerpt_pan_y - (1.0 / (16*(excerpt_zoom+1.0)))
	excerpt_set_pan()
end

function excerpt_pan_up()
	excerpt_pan_y = excerpt_pan_y + (1.0 / (16*(excerpt_zoom+1.0)))
	excerpt_set_pan()
end

function excerpt_zoominfo() 
	local message = "Zoom factor = " .. string.format("%4.2f", 1.0+excerpt_zoom)
	mp.osd_message(message, 3)
end

function excerpt_zoom_in() 
	excerpt_zoom = ((1.0 + excerpt_zoom) * excerpt_zoom_increment_factor) - 1.0
	if (excerpt_zoom > 15.0) then
		excerpt_zoom = 15.0
	end

	local i = math.floor(excerpt_zoom+0.5)
	
	if (i >= 1 and math.abs(excerpt_zoom - i) < 0.01) then
		-- snap to integer zoom factors when less than 1% away from them
		excerpt_zoom = i
	end
	
	excerpt_set_pan()
	mp.set_property("video-zoom", excerpt_zoom)
	
	excerpt_zoominfo()
end

function excerpt_zoom_out() 
	excerpt_zoom = ((1.0 + excerpt_zoom) / excerpt_zoom_increment_factor) - 1.0
	if (excerpt_zoom < 0.0) then
		excerpt_zoom = 0.0
	end
	
	local i = math.floor(excerpt_zoom+0.5)
	
	if (i >= 1 and math.abs(excerpt_zoom - i) < 0.01) then
		-- snap to integer zoom factors when less than 1% away from them
		excerpt_zoom = i
	end
	
	excerpt_set_pan()
	mp.set_property("video-zoom", excerpt_zoom)

	excerpt_zoominfo()
end


-- things to do whenever a new file was loaded:

function excerpt_on_loaded()
	-- pause play right after loading a file
  	mp.set_property("pause","yes")
	
	excerpt_zoom = 0.0
	mp.set_property("video-zoom", excerpt_zoom)	

	excerpt_pan_x = 0.0
	excerpt_pan_y = 0.0
	excerpt_set_pan()
end

mp.register_event("file-loaded", excerpt_on_loaded)

--

function excerpt_test(kevent)
	mp.msg.log("info", tostring(kevent))
	for k,v in pairs(kevent) do
	 	mp.msg.log("info", "kevent[" .. k .. "] = " .. tostring(v))
	end

	mp.commandv("seek", 0.0, "absolute", "exact")

end

--

mp.add_key_binding("i", "excerpt_mark_begin", excerpt_mark_begin_handler)
mp.add_key_binding("shift+i", "excerpt_seek_begin", excerpt_seek_begin_handler)
mp.add_key_binding("o", "excerpt_mark_end", excerpt_mark_end_handler)
mp.add_key_binding("shift+o", "excerpt_seek_end", excerpt_seek_end_handler)
mp.add_key_binding("x", "excerpt_write", excerpt_write_handler)

mp.add_key_binding("shift+right", "excerpt_keyframe_forward", excerpt_keyframe_forward, { repeatable = true; complex = true })
mp.add_key_binding("shift+left", "excerpt_keyframe_back", excerpt_keyframe_back, { repeatable = true; complex = true })
mp.add_key_binding("right", "excerpt_frame_forward", excerpt_frame_forward, { repeatable = true; complex = true })
mp.add_key_binding("left", "excerpt_frame_back", excerpt_frame_back, { repeatable = true; complex = true })

mp.add_key_binding("e", "excerpt_zoom_in", excerpt_zoom_in, { repeatable = true; complex = false })
mp.add_key_binding("w", "excerpt_zoom_out", excerpt_zoom_out, { repeatable = true; complex = false })

mp.add_key_binding("ctrl+right", "excerpt_pan_right", excerpt_pan_right, { repeatable = true; complex = false })
mp.add_key_binding("ctrl+left", "excerpt_pan_leftt", excerpt_pan_left, { repeatable = true; complex = false })
mp.add_key_binding("ctrl+up", "excerpt_pan_up", excerpt_pan_up, { repeatable = true; complex = false })
mp.add_key_binding("ctrl+down", "excerpt_pan_down", excerpt_pan_down, { repeatable = true; complex = false })

-- mp.add_key_binding("shift+mouse_btn3", "excerpt_test", excerpt_test, { repeatable = false; complex = true })
-- mp.add_key_binding("shift+mouse_btn4", "excerpt_test", excerpt_test, { repeatable = false; complex = true })
-- mp.add_key_binding("y", "excerpt_test", excerpt_test, { repeatable = false; complex = true })

excerpt_rangeinfo()