forked from mia/Aegisub
134 lines
4.2 KiB
Lua
134 lines
4.2 KiB
Lua
--[[
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Sample script for OverLua
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- demonstrate basic reading in an ASS subtitle file and rendering its lines on the video
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Given into the public domain.
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(You can do anything you want with this file, with no restrictions whatsoever.
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You don't get any warranties of any kind either, though.)
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Originally authored by Niels Martin Hansen.
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]]
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-- overlua_datastring is the string given to data= argument in Avisynth filter invocation
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timing_input_file = overlua_datastring
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-- You may want to get these from somewhere else
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-- Or just stick to hardcoding all styling information
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font_name = "Arial"
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font_size = 24
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-- A little check that an input file was actually given
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assert(timing_input_file, "Missing input file")
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-- An easier way to convert a string to a number and be guaranteed to get something useful
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function parsenum(str)
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return tonumber(str) or 0
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end
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-- Convert an ASS timestamp into a number of seconds
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function parse_ass_time(ass)
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local h, m, s, cs = ass:match("(%d+):(%d+):(%d+)%.(%d+)")
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return parsenum(cs)/100 + parsenum(s) + parsenum(m)*60 + parsenum(h)*3600
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end
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-- Not used here, but do some basic \k timing parsing
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function parse_k_timing(text)
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local syls = {}
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local i = 1
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for timing, syltext in text:gmatch("{\\k(%d+)}([^{]*)") do
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local syl = {dur = parsenum(timing)/100, text = syltext, i = i}
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table.insert(syls, syl)
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i = i + 1
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end
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return syls
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end
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-- Really stupid ASS parser
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function read_input_file(name)
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for line in io.lines(name) do
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-- You can catch Style lines in the same way if you want
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local start_time, end_time, style, fx, text = line:match("Dialogue: 0,(.-),(.-),(.-),.-,0000,0000,0000,(.-),(.*)")
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if text then
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local ls = {}
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ls.start_time = parse_ass_time(start_time)
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ls.end_time = parse_ass_time(end_time)
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ls.style = style
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ls.fx = fx
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ls.rawtext = text
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ls.kara = parse_k_timing(text)
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-- Clear out override blocks
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ls.cleantext = text:gsub("{.-}", "")
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table.insert(lines, ls)
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end
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end
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end
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-- Initialisation function, intended to be run on the first frame
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-- I think it's better to delay initialisation until first frame is requested
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-- rather than doing it immediately at load time.
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-- I believe much encoding software might be more graceful about that.
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function init()
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if inited then return end
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inited = true
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lines = {}
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read_input_file(timing_input_file)
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end
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-- Actual work function, this is what's called by OverLua for each frame
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-- f is a video frame object, what we'll be drawing to
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-- t is the timestamp of the frame, given in seconds (floating point)
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function render_frame(f, t)
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-- Just call init() every time, init itself makes sure it doesn't init more than once
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init()
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-- Find lines to be drawn
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-- NOTE: This structure is very simplistic.
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-- Advanced karaoke effects will probably need to build an object/effect list
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-- as initialisation and then instead go over the list of objects/effects per frame,
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-- instead of going over lines.
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-- (Ie. preprocessing in the style of ASS karaoke generation.)
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for i, line in pairs(lines) do
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if line.start_time <= t and line.end_time > t then
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-- Initial position of line
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local x = 0
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local y = f.height - 25
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-- Initialise drawing surface and context
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local surf = cairo.image_surface_create(f.width, f.height, "argb32")
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local c = surf.create_context()
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-- Select our font
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c.select_font_face(font_name)
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c.set_font_size(font_size)
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-- Get sizing information for font and line text
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if not line.te then line.te = c.text_extents(line.cleantext); line.fe = c.font_extents() end
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-- Calculate centered position
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x = (f.width - line.te.width) / 2 - line.te.x_bearing
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-- Produce text path
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c.move_to(x, y)
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c.text_path(line.cleantext)
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-- Draw a black border
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-- It will be centered on the text outline
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c.set_line_width(4)
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c.set_line_join("round") -- default is "miter"
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c.set_source_rgba(0, 0, 0, 1)
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-- "preserve" to keep the text path in the context
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c.stroke_preserve()
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-- Apply a little box blur to the border, effectively \be1
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raster.box_blur(surf, 3)
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-- Draw a white fill - this will draw over the inner part of the border
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c.set_source_rgba(1, 1, 1, 1)
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c.fill()
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-- Overlay on video
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f.overlay_cairo_surface(surf, 0, 0)
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end
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end
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end
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