matroska-subtitles

matroska-subtitles

Transform stream for parsing embedded .mkv subtitles.

Currently supports extraction of the .srt and .ass format.

install

npm install matroska-subtitles

documetation

The data event of the stream will emit an array that determines the type of the data. When a new subtitle track is encountered a track number and language is emitted:

data = [ 'new', { track: <track number>, language: <string> } ]

Subsequently a specific subtitle track will emit data of this form:

data = [ <track number>, { text: <string>, time: <ms>, duration: <ms> } ]

example

The following is an example of extracting subtitle tracks of an mkv:

const fs = require('fs')
const matroskaSubtitles = require('matroska-subtitles')

var tracks = new Map()
var subs = matroskaSubtitles()

subs.on('data', function (data) {
  if (data[0] === 'new') {
    var key = data[1].track
    tracks.set(key, {
      language: data[1].language,
      subtitles: []
    })
  } else {
    var key = data[0]
    var subtitle = data[1]
    tracks.get(key).subtitles.push(subtitle)
  }
})

subs.on('end', function () {
  tracks.forEach((track) => console.log(track))
})

fs.createReadStream('Sintel.2010.720p.mkv').pipe(subs)

Notice that this example doesn't take advantage of streaming since the subtitles first are being outputted when the stream ends.

response

The response of this example would look like this:

{ language: 'eng',
  subtitles: 
   [ { text: 'This blade has a dark past.',
       time: 107250,
       duration: 1970 },
     { text: 'It has shed much innocent blood.',
       time: 111800,
       duration: 4000 },
     { text: 'You\'re a fool for traveling alone,\r\nso completely unprepared.',
       time: 118000,
       duration: 3450 } ] }

Note that the language might be undefined if the mkv track has not specified it.

contributing

This is still a work in progress.

If you find a bug or have suggestions feel free to create an issue or a pull request!

see also

mkv-subtitle-extractor

license

MIT