Advanced SubStation Alpha subtitle plugin for videojs
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SunnyLi feat: improve subtitle switching
plugin now use videojs' built in caption switcher.

Refs #19
Latest commit a884c6b Aug 21, 2017


Add Advanced SubStation Alpha (ASS) subtitles support to videojs using the libjass library.

Check out the demo here


For plugin that supports videojs v5.x install using either:

  • bower install videojs-ass


  • npm install videojs-ass

For videojs v4:

Just specify version to be within:

"videojs-ass": ">=0.3.0 < 0.5.0"

for bower or npm whichever you prefer using.


Initialize the ass plugin with the src field like the following:

videojs('player_id', {
  plugins: {
    ass: {
      src: 'subs/subtitles.ass'
Option Default Description
src -1 .ass / .ssa source.
label -2 subtitle track label that shows up in the subtitles picker
delay 03 delay subtitle rendering by the specified value in seconds
rate 1 subtitle update speed relative to video playback rate
enableSvg true see here regarding SVG filter
fontMap - see here regarding using custom web fonts
fontMapById - alternate to above, takes id and runs this
videoWidth -3 metadata to assist in determining the optimal (cont below)
videoHeight -3 (cont) subtitle letterboxing ratio


  1. This property is required!
  2. Has fallback values but you should provide a better label.
  3. Value can be negative
  4. Generally, you should set these values when using external videojs providers as they might not expose the video dimensions to the player.