smi2vtt/dist/parse.js

Convert .smi to .vtt

'use strict';

var htmlparser = require('htmlparser2');

/**
 * generate time-text from milliseconds
 * @param  {String} time
 * @return {String}
 */
function generateTime(time) {
  return new Date(time * 1).toISOString().slice(11, -1);
}

/**
 * try parse
 * @param  {String} smiText
 * @return {Parser}
 */
function parse(smiText) {
  var vttText = 'WEBVTT\n';
  var type = null;

  var caption = {
    start: 0,
    end: 0,
    text: ''
  };

  var parser = new htmlparser.Parser({

    onopentag: function onopentag(name, attribs) {
      switch (name) {
        // comment
        case 'title':
          type = 'comment';
          vttText += '\nNOTE\n';
          break;

        // text
        case 'sync':
          type = 'caption';

          // start
          if (!caption.text) {
            caption.start = generateTime(attribs.start);
          }
          // end
          else {
              var time = generateTime(attribs.start);
              caption.end = time;
              vttText += caption.start + ' --> ' + caption.end + '\n';
              vttText += caption.text + '\n\n';

              caption.start = time;
              caption.text = '';
            }
          break;

        // br
        case 'br':
          caption.text += '\n';
          break;
      }
    },

    onclosetag: function onclosetag(text) {
      switch (type) {
        case 'comment':
          vttText += '\n\n';
          type = null;
          break;
      }
    },

    ontext: function ontext(text) {
      switch (type) {
        case 'comment':
          vttText += text.trim();
          break;

        case 'caption':
          caption.text += text.trim();
          break;
      }
    }

  }, { decodeEntities: true });
  parser.write(smiText);
  parser.end();

  return vttText;
}

module.exports = parse;