I'm new to using the audio tag in HTML 5 and wanted to build a player. I wanted to test using a VTT file in a track tag to see how closed captioning could work.
Here is my code:
<audio controls>
<source src="myaudio.mp3" type="audio/mpeg">
<track kink="caption" src="myaudio.vtt" srclang="en" label="English">
</audio>
According to what I've read, track is supposed to work for both audio and video, which makes sense from an accessibility stand-point. What doesn't make sense is the error I get trying to load it:
"Text track from origin 'file://' has been blocked from loading: Not at same origin as the document, and parent of track element does not have a 'crossorigin' attribute. Origin 'null' is therefore not allowed access."
When looking up the crossorigin attribute, I get a lot of confusing articles about CORS and the expected values of "anonymous" and "user-certificate". Trying either results in a similar error.
Any ideas as to why this won't work?
See here for an update list of browser with native WebVTT support. If your browser does not support native CC as WebVTT you have to construct your own parser in JavaScript to display them (note there are other CC format like SRT and TTML/DFXP).
You can find reliable information about the track element here and here. Note that there is a difference between what is referred to as subtitles, captions and descriptions.
Most browsers won't support a track tag when used with an audio tag - though in theory they should - you will find practically it does not work as of today. Maybe it has something to do with WebVTT meaning Web Video Text Tracks. This is described here.
You have to build your own parser if you want to display your closed captions along an audio tag. I would suggest you take a look at the source of mediaelementjs to get an idea on how to tackle this.
CORS is only required when you are requesting CC files that are not on the same domain as the page hosting the audio/video tag. It should not be necessary in your case. More about CORS.
Your error message seems to indicate you have a misconfiguration somewhere in your system (maybe your vtt file is on NFS?).