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Bug 25636 - [WebVTT] Regions should not change the font size or line height
Summary: [WebVTT] Regions should not change the font size or line height
Alias: None
Product: TextTracks CG
Classification: Unclassified
Component: WebVTT (show other bugs)
Version: unspecified
Hardware: PC All
: P2 normal
Target Milestone: ---
Assignee: This bug has no owner yet - up for the taking
QA Contact: Web Media Text Tracks CG
Whiteboard: v1
Depends on:
Reported: 2014-05-09 19:48 UTC by Philip Jägenstedt
Modified: 2015-11-05 14:14 UTC (History)
4 users (show)

See Also:


Description Philip Jägenstedt 2014-05-09 19:48:44 UTC
Without regions the default font is '5vh sans-serif'. With regions font is '(0.0533/1.3)vh sans-serif' and line-height is '0.0533vh'. (The values are 100 times too small, but that's just a typo.)

This is weird, as mixing regions and plain cues would result in differently sized text unless overridden.

Those who want to emulate 608 (80/15=5.33) can do so by changing the font using CSS, e.g.

::cue {
  font: 4.1vh monospace;
  line-height: 5.33vh;
Comment 1 Silvia Pfeiffer 2014-05-12 01:26:44 UTC
Fair enough. Happy to drop the font fix and leave that to the emulation spec.

The line-height fix was done such that lines in rollup mode don't change height based on the text within.

See also Rick's helpful article at .
Comment 2 Philip Jägenstedt 2014-05-12 22:07:22 UTC
Rick, are you using the average line height in Firefox's WebVTT implementation? The spec says "Let step be the height of the first line box in boxes." and that's what Presto does at least. I'm not exactly sure what it is that Blink/WebKit does...
Comment 3 Simon Pieters 2015-11-05 14:12:08 UTC
Setting line-height to some value doesn't help with the height depending on the text. I think the line height only changes if you change the font or font size, which is still possible. So I don't see any reason to specify a line-height that is different from the CSS initial value here.
Comment 4 Simon Pieters 2015-11-05 14:14:22 UTC