Convert and generate ObjectURL of WebVTT from srt format subtitle on the fly over HTML5 environment

HTMLMediaElement/Video doesn't support .srt (SubRip Track) format subtitle as its <track> source - in order to show captions of your video track either you have to convert the SRT file to WebVTT or write it on your own. Because <track src="VALID URL SCHEME"> requires a valid URL of .vtt (Web Video Text Track) formated subtitle track. This library will let you do this on the fly and will give you an URL to set the source of caption track.

Example

https://imshaikot.github.io/srt-webvtt/

Installation

$ npm install srt-webvtt --save

OR umd builds are also available

<script src="https://unpkg.com/srt-webvtt/umd/index.min.js"></script>

Getting Started

Using it very easy but a little tricky indeed. To getting started:

// Using ES6
import VTTConverter from 'srt-webvtt'; // This is a default export, so you don't have to worry about the import name

// Not using ES6
var VTTConverter = require('srt-webvtt');

Example and API

When you're about to use HTMLMediaElement (example: <video>) and you want to show caption on your video player - there's a native feature that will allow you to do that. See the official MDN article and tutorial of this <track> feature

Adding captions and subtitles to HTML5 video

But this feature is limited to WebVTT format and won't allow you to use SRT (very commonly used subtitle)

So, this tiny library will take your .srt subtitle file or a Blob object and will give you converted .vtt file's valid Object URL that you can set as <track>'s source.

See the Example below:

import VTTConverter from 'srt-webvtt';

const vttConverter = new VTTConverter(input.files[0]); // the constructor accepts a parameer of SRT subtitle blob/file object

vttConverter
.getURL()
.then(function(url) { // Its a valid url that can be used further
  var track = document.getElementById('my-sub-track'); // Track element (which is child of a video element)
  var video = document.getElementById('my-video'); // Main video element
  track.src = url; // Set the converted URL to track's source
  video.textTracks[0].mode = 'show'; // Start showing subtitle to your track
})
.catch(function(err) {
  console.error(err);
})

Constructor(Blob) The constructor must a valid Blob reference to a valid srt file

getURL() resolves a promise with the converted subtitle's Object URL or rejects with appropriate error.

release() as long as you're done with the URL and subtitle you call this instance method to release the memory.

LICENSE

MIT