RE: ISSUE-284: value of lineHeight [TTML2]

Glenn-

 

You assumed a cause and effect that was not intended.  The implementations have been around a long time.  No one I know used 100% in practice since it looked terrible.  The editor’s draft for 120% was the first clear guidance for the few that noticed it.  How long it was published is not really relevant - it happened and it was noticed.

 

I was asked to raise this issue in yesterday’s meeting in the context of overall deterministic layout, so here it is.  And, when we made the recommendation of 125%, we agreed we would revisit it in TTML2. 

 

The answer should be guided in my opinion by compatibility with related W3C work, aesthetics and common commercial practices. If, in the end, we settle on 125%, that’s fine. The point here is that we should revisit it as agreed, and in the broader layout context.

 

Regards,

 

                Mike

 

From: Glenn Adams [mailto:glenn@skynav.com] 
Sent: Friday, October 11, 2013 8:36 AM
To: Timed Text Working Group
Subject: Re: ISSUE-284: value of lineHeight [TTML2]

 

Given that the 120% only lived in an editor's draft, and only for 12 days (from Aug 23 to Sep 04) [1][2], I completely discount implementations that want to lock in that behavior. IMO, they should simply change to 125%.

 

TTML2 was already changed to make this normative on Sep 4 [3].

 

[1] https://dvcs.w3.org/hg/ttml/rev/15f347a0d2ef

[2] https://dvcs.w3.org/hg/ttml/rev/11d2d5dcb5a1

[3] https://dvcs.w3.org/hg/ttml/rev/0cc9f1196066

 

On Fri, Oct 11, 2013 at 9:11 AM, Timed Text Working Group Issue Tracker <sysbot+tracker@w3.org> wrote:

ISSUE-284: value of lineHeight [TTML2]

http://www.w3.org/AudioVideo/TT/tracker/issues/284

Raised by: Mike Dolan
On product: TTML2

TTML1SE added a non-normative recommendation for lineHeight:  8.2.12: "Note: It is recommended that presentation processors use a computed line height that is 125% of the size of the largest applicable font size when the value normal is specified. The choice of 125% allows use of a font size of 0.8c in order to obtain a line height of 1c."

However, the WG had previously agreed to 120% which was codified in an editor's draft after closing ISSUE-275. The issue includes the rationale. The Note was a last minute change for the reason stated in the last sentence in the note.

Implementations had been developed to roughly 120% which was re-enforced by the editor's draft text.

This recommendation should be revisited and normative provisions added to TTML2.

This is also related to ISSUE-283.