mdn
html.elements.track - No UA supports `kind="descriptions"`
What type of issue is this?
Incorrect support data (example: BrowserX says "86" but support was added in "40")
What information was incorrect, unhelpful, or incomplete?
The table shows all browsers support the kind attribute and have for years. However, no browser supports the descriptions value, which is intended for UAs to use to synthesize audio descriptions.
What browsers does this problem apply to, if applicable?
Chromium (Chrome, Edge 79+, Opera, Samsung Internet), Firefox, Safari
What did you expect to see?
Partial support for kind attribute.
Did you test this? If so, how?
Yes. I built a demo and tested: https://adrianroselli.com/2023/12/ad-support-in-html-video.html#Synthesized
Can you link to any release notes, bugs, pull requests, or MDN pages related to this?
WHATWG HTML outlines how it should work:
Textual descriptions of the video component of the media resource, intended for audio synthesis when the visual component is obscured, unavailable, or not usable (e.g. because the user is interacting with the application without a screen while driving, or because the user is blind). Synthesized as audio.
WHATWG HTML even has parsing rules:
One example of when a media element would be paused for in-band content is when the user agent is playing audio descriptions from an external WebVTT file, and the synthesized speech generated for a cue is longer than the time between the text track cue start time and the text track cue end time.
But I think WHATWG HTML punted to WebVTT, and I think WebVTT itself has not sorted this:
The majority of the current version of this specification is dedicated to describing how to use WebVTT files for captioning or subtitling. There is minimal information about chapters and time-aligned metadata and nothing about video descriptions at this stage.
So while this may be a double-spec issue, it is still reported incorrectly here.
Do you have anything more you want to share?
Consider breaking the table down further by the values of kind and noting support for each:
-
captions -
chapters -
descriptions -
metadata -
subtitles
MDN URL
https://developer.mozilla.org/en-US/docs/Web/HTML/Element/track
MDN metadata
MDN page report details
- Query:
html.elements.track - Report started: 2023-12-20T14:27:44.138Z
And I filed (or updated) the relevant bugs with the browsers:
- Chromium: https://bugs.chromium.org/p/chromium/issues/detail?id=1447858#c4
- WebKit: https://bugs.webkit.org/show_bug.cgi?id=266724
- FIrefox: https://bugzilla.mozilla.org/show_bug.cgi?id=1871143
Thanks for all your research! I've created https://github.com/mdn/browser-compat-data/pull/21720 to add <track kind='descriptions'> to the compat data.
@Elchi3 @teoli2003 I guess this issue can be close as the data has been added in #21720
