[mythtv-theming] New for 0.26 - osd_subtitle.xml

[Jim Stichnoth]

In 0.26 (and currently in Master), there will be a new theming
opportunity for subtitle/caption formatting.  Specifically, the theme
now controls fonts, colors, and backgrounds of text-based closed
captions and subtitles.  This formatting is expressed as a combination
of provider values (i.e., attributes that are part of the
subtitle/caption stream) and theme overrides.

This is controlled by a new file called osd_subtitle.xml, which should
be in the top-level theme directory, alongside osd.xml, base.xml, etc.
 The osd_subtitle.xml file is optional.  If it's not present, the
provider defaults are used.

The file and its capabilities are documented at
http://www.mythtv.org/wiki/Osd_subtitle.xml .

Here are a few things I imagine a theme might like to change/specify:
o Use a different choice of fonts
o Change the font size
o Adjust the background (e.g. opacity) of CEA-608 and/or text captions
o Set outline or shadow for CEA-608 and/or text captions without a background

A comment on the last item.  By default, 0.26 puts an opaque black
background behind text (e.g. .srt) and CEA-608 captions.  Some people
prefer to have no background (alpha=0).  If you do this, be sure to
specify in the fontdef a black outline or shadow of about 2 pixels so
that the text remains readable.

Let me know if you have any questions or find any problems.

Jim