ISSUE-234: Drop Shadow character style

Drop Shadow

Drop Shadow character style

State:
CLOSED
Product:
TTML2
Raised by:
Pierre-Anthony Lemieux
Opened on:
2013-05-30
Description:
[The following is extracted from the liaison received from SMPTE at https://lists.w3.org/Archives/Member/w3c-archive/2012Sep/0214.html]

See Section 6.4.3, 6.4.8 and 6.4.12 at ST 428-7.

It shall be possible to apply a drop shadow style parameter to a <span> element for the purpose of altering the contrast of the rendered text against the primary picture.

The application of the parameter shall result in the drawing of a drop shadow behind each character, falling diagonally to the bottom and right of each character.

It shall be possible to specify the color (including alpha channel) and thickness of the drop shadow. The thickness shall be expressed as a positive decimal number in units of em.

The drop shadow effect shall remain on the bottom and right of each character, whatever the progression direction.
Related Actions Items:
No related actions
Related emails:
  1. Re: [ttml2] Action-369 Action-382 - draft dispositions flattened thread incorporating changes (from nigel.megitt@bbc.co.uk on 2015-03-19)
  2. Re: [ttml2] Action-369 - collate smpte issues and draft dispositions (from nigel.megitt@bbc.co.uk on 2015-03-18)
  3. Re: [ttml2] Action-369 - collate smpte issues and draft dispositions (from glenn@skynav.com on 2015-03-05)
  4. Re: [ttml2] Action-369 - collate smpte issues and draft dispositions (from nigel.megitt@bbc.co.uk on 2015-03-05)
  5. Re: [ttml2] Action-369 - collate smpte issues and draft dispositions (from glenn@skynav.com on 2015-03-04)
  6. Re: [ttml2] Action-369 - collate smpte issues and draft dispositions (from nigel.megitt@bbc.co.uk on 2015-03-04)
  7. Re: [ttml2] Action-369 - collate smpte issues and draft dispositions (from nigel.megitt@bbc.co.uk on 2015-02-25)
  8. [ttml2] Action-369 - collate smpte issues and draft dispositions (from nigel.megitt@bbc.co.uk on 2015-02-06)
  9. {minutes} TTWG Meeting 2015-01-15 (from nigel.megitt@bbc.co.uk on 2015-01-15)
  10. {agenda} TTWG Meeting 2015-01-15 (from nigel.megitt@bbc.co.uk on 2015-01-14)
  11. {minutes} TTML Meeting of 24/10/13 (from glenn@skynav.com on 2013-10-24)
  12. RE: TTML Agenda for 24/10/13 (from mdolan@newtbt.com on 2013-10-23)
  13. TTML Agenda for 24/10/13 (from nigel.megitt@bbc.co.uk on 2013-10-23)
  14. ISSUE-234 (Drop Shadow): Drop Shadow character style [TTML.next] (from sysbot+tracker@w3.org on 2013-05-30)

Related notes:

This appears to be a proposal to support features of the CSS3 Text Decoration Module's text-shadow [1] property that aren't currently supported by tts:textOutline, e.g., a shadow offset in both x and y axes as opposed to being a pure outline effect.

[1] http://dev.w3.org/csswg/css-text-decor-3/#text-shadow-property

Glenn Adams, 30 May 2013, 20:39:43

[Sean]: needs to meet the requirements of US closed captions

6 Jun 2013, 14:58:14

For additional clarity on the communication from SMPTE, there is an attempt to enhance TTML to support the edge styles required by the FCC, in addition to the IMF needs.

Specifically, we need a way to map the following 708 edge types into TTML with the same presentation affect:

NONE, RAISED, DEPRESSED, UNIFORM, LEFT_DROP_SHADOW, RIGHT_DROP_SHADOW

Unfortunately CEA 708 and the FCC are not very prescriptive about exactly what these all mean – “Manufacturers have a bit of latitude in how these border effects are achieved.” The FCC did not elaborate.

However, example presentations can be found in CEA 708, Section 8.5.8.2, Figure 19.

Mike Dolan, 6 Jun 2013, 16:25:06

text-shadow appears to satisfy ST 428-7 requirements

Pierre-Anthony Lemieux, 21 Oct 2013, 20:41:40

Pal: P2

Philippe Le Hégaret, 24 Oct 2013, 15:46:09

addressed by https://dvcs.w3.org/hg/ttml/rev/369e36a8cecd

Glenn Adams, 8 Jan 2015, 08:27:54

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David Singer <singer@apple.com>, Nigel Megitt <nigel.megitt@bbc.co.uk>, Chairs, Thierry Michel <tmichel@w3.org>, Philippe Le Hégaret <plh@w3.org>, Atsushi Shimono <atsushi@w3.org>, Staff Contacts
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