transcode .ass, .ssa, .txt to SRT

ssa2srt.js

  //transcode .ass, .ssa, .txt to SRT
  var convert2srt = function (file, ext, callback) {
      var readline = require('readline'),
          counter = null,
          lastBeginTime,

          //input
          orig = /([^\\]+)$/.exec(file)[1],
          origPath = file.substr(0, file.indexOf(orig)),

          //output
          srt = orig.replace(ext, '.srt'),
          srtPath = Settings.tmpLocation,

          //elements
          dialog, begin_time, end_time;

      fs.writeFileSync(path.join(srtPath, srt), ''); //create or delete content;
      console.debug('SUB format can be converted:', orig);

      var rl = readline.createInterface({
          input: fs.createReadStream(path.join(origPath, orig)),
          output: process.stdout,
          terminal: false
      });
      rl.on('line', function (line) {

          //detect encoding
          var charset = charsetDetect.detect(line);
          var encoding = charset.encoding;
          var line_, parsedBeginTime, parsedEndTime, parsedDialog;

          //parse SSA
          if (ext === '.ssa' || ext === '.ass') {
              encoding = 'utf-8';
              if (line.indexOf('Format:') !== -1) {
                  var ssaFormat = line.split(',');

                  for (var i = 0; i < ssaFormat.length; i++) {
                      switch (ssaFormat[i]) {
                      case 'Text':
                      case ' Text':
                          dialog = i;
                          break;
                      case 'Start':
                      case ' Start':
                          begin_time = i;
                          break;
                      case 'End':
                      case ' End':
                          end_time = i;
                          break;
                      default:
                      }
                  }

                  if (dialog && begin_time && end_time) {
                      console.debug('SUB formatted in \'ssa\'');
                  }
                  return; //we have the elms spots, move on to the next line
              }

              if (line.indexOf('Dialogue:') === -1) { //not a dialog line
                  return;
              }

              line_ = line.split(',');

              parsedBeginTime = line_[begin_time];
              parsedEndTime = line_[end_time];
              parsedDialog = line_[dialog];
              parsedDialog = parsedDialog.replace('{\\i1}', '<i>').replace('{\\i0}', '</i>'); //italics
              parsedDialog = parsedDialog.replace('{\\b1}', '<b>').replace('{\\b0}', '</b>'); //bold
              parsedDialog = parsedDialog.replace('\\N', '\n'); //return to line
              parsedDialog = parsedDialog.replace(/{.*?}/g, ''); //remove leftovers brackets 
          }

          //parse TXT
          if (ext === '.txt') {
              line_ = line.split('}');

              var formatSeconds = function (seconds) {
                  var date = new Date(1970, 0, 1);
                  date.setSeconds(seconds);
                  return date.toTimeString().replace(/.*(\d{2}:\d{2}:\d{2}).*/, '$1');
              };

              parsedBeginTime = formatSeconds(line_[0].replace('{', '') / 25);
              parsedEndTime = formatSeconds(line_[1].replace('{', '') / 25);
              parsedDialog = line_[2].replace('|', '\n');
          }

          //SRT needs a number for each subtitle
          counter += 1;

          //keep only the last lang
          if (parsedBeginTime < lastBeginTime) {
              counter = 1;
              fs.writeFileSync(path.join(srtPath, srt), '');
              console.debug('SUB contains multiple tracks, keeping only the last');
          }

          //SRT formatting
          var parsedLine =
              counter + '\n' +
              parsedBeginTime + ' --> ' + parsedEndTime + '\n' +
              parsedDialog;

          fs.appendFileSync(path.join(srtPath, srt), '\n\n' + parsedLine, encoding);
          lastBeginTime = parsedBeginTime;
      });

      setTimeout(function () {
          fs.readFile(path.join(srtPath, srt), function (err, dataBuff) {
              if (!err) {
                  console.debug('SUB transcoded to SRT:', srt);
                  callback(dataBuff);
              } else {
                  console.warn('SUB transcoding failed', err);
              }
          });
      }, 2000);
  };

It is crappy and needs serious rewrite, but I scavenged that from popcorntime and found it useful, although I have nor the time nor the will to rewrite it or deeply analyze it.