Get Started with HTML Video Captions
Published
Did you know you can add captions to <video>
elements with a little HTML and a VTT file? I didn’t know until today! It’s really easy to do (so long as you format your VTT file correctly… shout out to Conlin Durbin for helping me find that error 😄). At a minimum, you need 3 files:
- Video, probably
.mp4
- WebVTT, where the captions are
- HTML
Let’s get started
The HTML
<video width="100%" title="Puppy" controls>
<source src="Puppiness.mp4" type="video/mp4" />
<track src="transcript.vtt" label="English captions" default />
</video>
This is the easiest step. You only need 3 elements. On the <video>
element, make you sure you include the controls
attribute. This will allow users to toggle captions or switch to a different langue, if applicable.
The <source>
element should be your video. Specify its src
and type
attributes. The <track>
element is for the .vtt
file you’ll create in the next step. There are multiple attributes to include here.
kind
defaults to “subtitles”, but if you specify it you must also include thesrclang
attribute.label
is the title of the track and will be displayed in the video controls menu where captions can be toggled.default
is included to set a track as enabled.
WebVTT
WEBVTT
1
00:00:00.000 --> 00:00:01.000
SAND? OM NOM
2
00:00:02.000 --> 00:00:04.000
NO, BLEH
3
00:00:04.000 --> 00:00:08.000
LEASH! OM NOM
4
00:00:08.000 --> 00:00:10.000
GIVE IT
5
00:00:10.000 --> 00:00:14.000
IS MINE
The format for this file is very specific. You must include “WEBVTT” at the top of the file, and then there are sections with white space in between which are called “cues”. In the example file I’ve attached above, the first line of each cue is called the identifier. The next line specifies the timing for the cue. Finally, we have the cue payload. This is where you include the content for each caption. You can do some styling here.
The final product
Here’s a GIF preview of the captions I added to a video of a puppy playing on a sandy beach.
More resources
I wasn’t able to find a ton of examples out there, but there are plenty of resources that get into the differences between subtitles and captions, styling abilities, and additional ways to accomplish the same thing as above but with different transcript formats or third-party libraries.
- “How-to: Using captions with HTML’s video element” (The A11Y Project)
- “Web Video Text Tracks Format (WebVTT)” (MDN)
- “HTML
<track>
Tag” (w3schools)