webvtt2ass/lib/subtitle.text.js

Convert WebVTT into ASS Subtitle

"use strict";
const he       = require("he");
const TimeSpan = require("./timespan");

const default_font = "Arial";

function assHeader(font) {
    font = font || default_font;

    const header = [
        "[Script Info]\n; Script generated by webvtt2ass\nScriptType: v4.00+\nWrapStyle: 0\nScaledBorderAndShadow: yes\nYCbCr Matrix: None\nPlayResX: 1920\nPlayResY: 1080\n",
        "[V4+ Styles]\nFormat: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, OutlineColour, BackColour, Bold, Italic, Underline, StrikeOut, ScaleX, ScaleY, Spacing, Angle, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, Encoding",
        `Style: Default,${font},50,&H00FFFFFF,&H000000FF,&H00000000,&H00000000,0,0,0,0,100,100,0,0,1,2,0.5,2,10,10,10,1`,
        `Style: Ruby,${font},50,&H00FFFFFF,&H000000FF,&H00000000,&H00000000,0,0,0,0,100,100,0,0,1,2,0.5,2,10,10,10,1`,
        "[Events]\nFormat: Layer, Start, End, Style, Actor, MarginL, MarginR, MarginV, Effect, Text",
        "Comment:  0,00:00:00.00,00:00:00.00,Ruby,,0,0,0,template furi,{\\pos(!line.left+syl.center!,!line.middle-line.height!)\\an5}",
        "Comment:  0,00:00:00.00,00:00:00.00,Ruby,,0,0,0,template syl,{\\pos(!line.left+syl.center!,!line.middle!)\\an5}"
    ];
    return header.join("\n") + "\n";
}

function html2assColor(color) {
    if (color.startsWith("color")) {
        return `&H${color.substr(9, 2)}${color.substr(7, 2)}${color.substr(5, 2)}&`;
    }
    // todo: cast red to &H0000FF&
    return color;
}

//src: <ruby>明日<rt>あした</tr></ruby>また<ruby>会<rt>あう</rt></ruby><ruby>時<rt>とき</rt></ruby>
//tgt: {\k}明日|あした{\k}また{\k}会|あう{\k}時|とき
//ref: http://docs.aegisub.org/manual/Furigana_karaoke

function parseTreeRuby(tree) {
    let ret = "{\\k}";
    tree.children.forEach((item) => {
        if (item.type === "text") {
            ret += item.value;
        } else if (item.type === "object") {
            if (item.name === "rt") {
                ret += "|" + parseTreeInner(item, true).text;
                ret += "{\\k}";
            }
        }
    });
    return ret;
}

function parseTreeInner(tree, noTag) {
    const nodes = tree.children;
    let ret = {text: ""};
    if (tree.name === "ruby") {
        ret.text += parseTreeRuby(tree);
        ret.style = "Ruby";
    } else {
        if (tree.name === "v") {
            ret.voice = tree.value;
        }
        nodes.forEach((item) => {
            if (item.type === "object") {
                const temp = parseTreeInner(item);
                ret.text += temp.text;
                ret.style = temp.style;
                if (ret.voice === undefined) {
                    ret.voice = temp.voice;
                }
            } else {
                ret.text += item.value;
            }
        });
        if (tree.name !== undefined && noTag === undefined) {
            if (tree.name !== "v") {
                // handle class
                if (tree.name === "c") {
                    const classes = tree.classes
                    // TODO: handle style info
                } else {
                    ret.text = "{\\" + tree.name + "1}" + ret.text + "{\\" + tree.name + "0}";
                }
            }
        }
    }
    return ret;
}

function parseSegment(line) {
    let ret = parseTreeInner(line.tree);
    if (ret.voice === undefined) {
        ret.voice = "";
    }
    if (ret.style === undefined) {
        ret.style = "Default";
    }
    ret.text = he.decode(ret.text).replace(/\n/g, "\\N");
    ret.begin = new TimeSpan(line.startTime).toString();
    ret.end   = new TimeSpan(line.endTime).toString();
    return ret;
}

module.exports = {parseSegment: parseSegment, assHeader: assHeader};