134 lines
4 KiB
Lua
134 lines
4 KiB
Lua
--[[
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assfile.lua - Functions for parsing ASS format subtitles
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Part of OverLua, licensed under GPLv2
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]]
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module "assfile"
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-- Parsing helper functions
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local function trim(s)
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return (s:gsub("^[ \t\r\n]*(.-)[ \t\r\n]*$", "%1"))
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end
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local function num(s)
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return tonumber(trim(s)) or 0
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end
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-- Which file format we're working with.
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-- Changing this changes the behaviour of various parsing functions.
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-- Valid values: "SSA4", "ASS", "ASS2", "ASS3", "AS5"
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-- Other versions aren't supported.
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-- This is usually automatically set by the whole-file parsing functions.
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format = "SSA4"
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-- Create a solid colour fill style
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-- Colours are "cairo compatible", ie. range 0 to 1
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-- A colour never stores alpha, that's a separate property
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function color(r, g, b, a)
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r, g, b, a = r or 0, g or 0, b or 0, a or 0
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return {class="solid", r=r, g=g, b=b, a=a}
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end
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-- Parse a colour in SSA, ASS or HTML format
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function parse_color(s)
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end
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-- Base style, this defines the defaults used for undefined fields in read-in styles
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default_style = {
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-- Default style has no name
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name = nil,
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-- Well, sensible on Windows
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font_face = "Arial",
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font_size = "24",
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font_language = "C", -- Language to assume text is in, affects some rendering
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font_vertical = false, -- Vertical layout, replaces use of "@-fonts"
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font_bold = false,
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font_italic = false,
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font_underline = false,
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font_overstrike = false,
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-- Fill style
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fill1 = color(1, 1, 1, 1), -- Fill, white
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fill2 = color(1, 0, 0, 1), -- Pre-karaoke fill, red
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fill3 = color(0, 0, 0, 1), -- Outline, black
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fill4 = color(0, 0, 0, 0.5), -- Shadow, semi-transparent black
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-- Border size
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outline = 2,
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shadow = 2,
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opaque_box = false,
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-- Scaling
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scale_x = 1.00,
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scale_y = 1.00,
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-- Spacing
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spacing_char = 0, -- Extra inter-character spacing
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spacing_line = 0, -- Extra inter-line spacing
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baseline_shift = 0, -- Shift baseline this amount against line advance direction
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-- Text positioning
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margin_l = 10,
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margin_r = 10,
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margin_t = 10,
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margin_b = 10,
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align_x = 0.5, -- Bouding box centered between left/right margins
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align_y = 1.0, -- Bounding box placed at bottom of screen
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inner_align_x = 0.5, -- Lines centered inside bounding box
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inner_align_y = 1.0, -- Lines at bottom of bounding box
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break_style = "smart_top", -- "Smart-wrap", earlier lines wider (alt. "smart_bottom", "simple", "none")
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pos_rel = "video", -- Positioning relative to video frame (alt. "screen")
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pos_x = nil, -- Don't override positioning
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pos_y = nil,
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-- Rotation/reshaping
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origin = nil, -- Automatic, at center of text
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angle_x = 0,
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angle_y = 0,
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angle_z = 0,
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shear_x = 0,
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shear_y = 0,
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baseline_transform = nil,
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bounding_box_transform = nil,
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-- Misc.
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blend_mode = "normal", -- Alt. "add", "multiply"
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clip_rect = nil,
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clip_shape = nil,
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blur = 0,
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-- Animation
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fade = nil,
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animation = nil
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}
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-- Parse a Style line
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function read_style(t)
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if format == "AS5" then
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error("Found Style line in an AS5 file, where it's unsupported.\nLine: %s", t)
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elseif format == "SSA4" then
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local name, font_face, font_size, color1, color2, color3, color4,
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bold, italic, underline, overstrike, border, outline, shadow,
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align, margin_l, margin_r, margin_v, alpha, encoding
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= t:match("^.-:(.-),(.-),(.-),(.-),(.-),(.-),(.-),(.-),(.-),(.-),(.-),(.-),(.-),(.-),(.-),(.-),(.-),(.-),(.-),(.-)$")
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name = trim(name)
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font_face = trim(name)
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font_size = num(font_size)
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end
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end
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-- Parse a StyleEx line
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function read_style_ex(t)
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if format ~= "ASS3" and format ~= "AS5" then
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error("Found StyleEx line in format that doesn't support it.\nFormat is \"%s\".\nLine is: %s", format, t)
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end
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end
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-- Merge two styles by "overlaying" a style upon a base
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-- Produces a new style
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-- Fields where the overlay has a defined value, the output style has the value of overlay,
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-- but in fields where overlay is nil, the output has the base value.
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-- (Pretty much "out.field = overlay.field or base.field".)
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-- Animation lists are merged however, but this may produce weird results
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-- if the animations overlap in non-trivial ways. (Just pretend this says "undefined behaviour.")
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function merge_styles(base, overlay)
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end
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