Self-hosted videos with HLS: subtitles
In a previous article, I have described a solution to self-host
videos while offering a delivery adapted to each user’s bandwidth,
thanks to HLS and hls.js. Subtitles1 were not part of
the game. While they can be declared inside the HLS manifest or
embedded into the video, it is easier to include them directly in the
<video> element, using the WebVTT format:
<video poster="poster.jpg" controls preload="none"> <source src="index.m3u8" type="application/vnd.apple.mpegurl"> <source src="progressive.mp4" type='video/mp4; codecs="avc1.4d401f, mp4a.40.2"'> <track src="de.vtt" kind="subtitles" srclang="de" label="Deutsch"> <track src="en.vtt" kind="subtitles" srclang="en" label="English"> </video>
Watch the following demonstration, featuring Agent 327: Operation Barbershop, a video created by Blender Animation Studio and currently released under the Creative Commons Attribution No Derivatives 2.0 license:
You may want to jump to 0:12 for the first subtitle.
Most browsers should display a widget to toggle subtitles.
just fine with Chromium but Firefox will not show the menu until
the video starts playing, unless you enable preloading. Another
annoyance: there is no simple way to specify safe margins for
subtitles and they get stuck at the bottom. These two issues seem
for a custom player.
If subtitles are served from another domain,
crossorigin="anonymous" attribute needs to be added to the
tag and subtitles need to handle CORS headers. On some browsers, this
also enables CORS for the video and the poster.
The issue with Firefox and the subtitle menu is fixed in Firefox 76. On Android, subtitles work from Firefox 80.