merge 2 srt files, using 1's timecodes and 2's text lines. nodejs.

merge2subs.js

/* merge2subs
 * 
 * Resync subtitle with another sub's timecodes
 *
 * @file_tc is the file you extract timecodes from;
 * @file_lines is the one you extract text from;
 *
 * both arguments are absolute path to SRT files
 *
 * @xpath is an absolute path to a directory, to save mixed.srt
 */

var merge2subs = function(file_tc, file_lines, xpath) {
    var readline = require('readline'),
        srt = 'mixed.srt',
        srtPath = xpath;

    fs.writeFileSync(path.join(srtPath, srt), ''); //create or delete content;

    var tc_sub = [];
    var count = null;

    var rl = readline.createInterface({
        input: fs.createReadStream(file_tc),
        output: process.stdout,
        terminal: false
    });
    rl.on('line', function(line) {
        if (!isNaN(line)) {
            // sub count
            count = parseInt(line);
            tc_sub[count] = {text: []};
        } else {
            // timecode or text
            if (line.match(/\d{2}\:\d{2}\:\d{2}\,\d{3}/)) {
                tc_sub[count].tc = line;
            } else {
                tc_sub[count].text.push(line);
            }
        }
    });

    var lines_sub = [];
    var counter = null;

    var rle = readline.createInterface({
        input: fs.createReadStream(file_lines),
        output: process.stdout,
        terminal: false
    });
    rle.on('line', function(line) {

        if (!isNaN(line)) {
            // sub count
            counter = parseInt(line);
            lines_sub[counter] = {text: []};
        } else {
            // timecode or text
            if (line.match(/\d{2}\:\d{2}\:\d{2}\,\d{3}/)) {
                lines_sub[counter].tc = line;
            } else {
                lines_sub[counter].text.push(line);
            }
        }
    });

    setTimeout(function() {
        for (var i = 1; i < tc_sub.length; i++) {
            //SRT formatting
            var parsedLine = '' + i + '\n' +
                tc_sub[i].tc + '\n' +
                lines_sub[i].text.join('\n');

            fs.appendFileSync(path.join(srtPath, srt), '\n\n' + parsedLine, 'utf-8');
        }
    }, 2000);
};