863485 - [webvtt] <track> does not parse data: URIs

Status: REOPENED

(Core :: Audio/Video: Playback, defect)

Description

[Ralph Giles (:rillian)]

Investigating the opera webvtt test suite I ran to an issue where we don't appear to handle data URI's for track.src. The test has code like:

  var t = document.createElement('track');
  t.src = 'data:text/vtt,'+encodeURIComponent('WEBVTT\n\n00:00.000 --> 00:01.000\nfoo');

We don't display anything with a source like this.

Test example: https://people.xiph.org/~giles/2013/vtt-01.html

Original Opera test: http://w3c-test.org/web-platform-tests/master/old-tests/submission/Opera/media/track/track-element/cloneNode.html although it's outdated in ways that don't agree with the current spec.

Comment 1

[Ralph Giles (:rillian)]

This isn't important until after we have more basic features working, but I wanted to get it tracked.

Comment 2

[Ralph Giles (:rillian)]

Tested with https://github.com/RickEyre/mozilla-central.git integration branch commit de894e21b1ae69c07648e917f3ccd5052a84e73b and media.webvtt.enabled=true in about:config.

Comment 3

[Ralph Giles (:rillian)]

FWIW, Chrome Canary 28 reports a CORS violation on the data uri.

Comment 4

[Caitlin Potter (:caitp)]

heh that's weird, how do you get a CORS violation from local data @_@

Comment 5

[Caitlin Potter (:caitp)]

heh that's weird, how do you get a CORS violation from local data @_@ like is that a desirable behaviour?

I mean, should we consider that to be a CORS violation in mozilla? (I don't know how we currently behave in this situation)

Comment 6

[Mardeg]

Thanks for reopening this dbaron, there are real world examples like http://neocities.org that don't allow text/vtt files to be uploaded where this would be useful.

Comment 7

[Radosław Włodkowski]

I've created jsfiddle:
http://jsfiddle.net/fixedmachine/ronaet82/

with sample which is addressing this issue. 

In Firefox 36.0.4 data URIs for <track> elements already seems to work fine, and it's the only browser right now with proper data URIs handling within <track> elements.

Chromium and WebKit based browsers report CORS errors. Internet Explorer 11 doesn't report any errors, but the subtitles embedded with data URI won't work.

I've tracked issues for:
- Chromium: https://code.google.com/p/chromium/issues/detail?id=472300
- WebKit: https://bugs.webkit.org/show_bug.cgi?id=143284
- Internet Explorer: https://connect.microsoft.com/IE/feedbackdetail/view/1217043/ie11-no-subtitles-displayed-when-track-element-has-src-specified-as-data-uri