lavc: add teletext decoder using libzvbi

Based on a patch by Wolfram Gloger <wmglo@dent.med.uni-muenchen.de>.
http://lists.ffmpeg.org/pipermail/ffmpeg-devel/2012-December/136677.html

The original patch was rebased by Tudor SUCIU <tudor.suciu@gmail.com>.

Lots of additional features and fixes are made by me.

Fixes ticket #2086.

Changes since last version:
- change default page to all pages

Signed-off-by: Marton Balint <cus@passwd.hu>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

2 files changed, 58 insertions, 0 deletions

diff --git a/doc/decoders.texi b/doc/decoders.texi
index aa82add080..9d9f298471 100644
--- a/doc/decoders.texi
+++ b/doc/decoders.texi
@@ -158,4 +158,45 @@ ee450d, 101010, eaeaea, 0ce60b, ec14ed, ebff0b, 0d617a, 7b7b7b, d1d1d1,
 7b2a0e, 0d950c, 0f007b, cf0dec, cfa80c, 7c127b}.
 @end table
 
+@section libzvbi-teletext
+
+Libzvbi allows libavcodec to decode DVB teletext pages and DVB teletext
+subtitles. Requires the presence of the libzvbi headers and library during
+configuration. You need to explicitly configure the build with
+@code{--enable-libzvbi}.
+
+@subsection Options
+
+@table @option
+@item txt_page
+List of teletext page numbers to decode. You may use the special * string to
+match all pages. Pages that do not match the specified list are dropped.
+Default value is *.
+@item txt_chop_top
+Discards the top teletext line. Default value is 1.
+@item txt_format
+Specifies the format of the decoded subtitles. The teletext decoder is capable
+of decoding the teletext pages to bitmaps or to simple text, you should use
+"bitmap" for teletext pages, because certain graphics and colors cannot be
+expressed in simple text. You might use "text" for teletext based subtitles if
+your application can handle simple text based subtitles. Default value is
+bitmap.
+@item txt_left
+X offset of generated bitmaps, default is 0.
+@item txt_top
+Y offset of generated bitmaps, default is 0.
+@item txt_chop_spaces
+Chops leading and trailing spaces and removes empty lines from the generated
+text. This option is useful for teletext based subtitles where empty spaces may
+be present at the start or at the end of the lines or empty lines may be
+present between the subtitle lines because of double-sized teletext charactes.
+Default value is 1.
+@item txt_duration
+Sets the display duration of the decoded teletext pages or subtitles in
+miliseconds. Default value is 30000 which is 30 seconds.
+@item txt_transparent
+Force transparent background of the generated teletext bitmaps. Default value
+is 0 which means an opaque (black) background.
+@end table
+
 @c man end SUBTILES DECODERS
diff --git a/doc/general.texi b/doc/general.texi
index b755c187ab..2a72d2ed1f 100644
--- a/doc/general.texi
+++ b/doc/general.texi
@@ -133,6 +133,20 @@ Go to @url{https://github.com/dekkers/libilbc} and follow the instructions for
 installing the library. Then pass @code{--enable-libilbc} to configure to
 enable it.
 
+@section libzvbi
+
+libzvbi is a VBI decoding library which can be used by FFmpeg to decode DVB
+teletext pages and DVB teletext subtitles.
+
+Go to @url{http://sourceforge.net/projects/zapping/} and follow the instructions for
+installing the library. Then pass @code{--enable-libzvbi} to configure to
+enable it.
+
+@float NOTE
+libzvbi is licensed under the GNU General Public License Version 2 or later
+(see @url{http://www.gnu.org/licenses/old-licenses/gpl-2.0.html} for details),
+you must upgrade FFmpeg's license to GPL in order to use it.
+@end float
 
 
 @chapter Supported File Formats, Codecs or Features
@@ -947,6 +961,7 @@ performance on systems without hardware floating point support).
 @item 3GPP Timed Text  @tab   @tab   @tab X @tab X
 @item AQTitle          @tab   @tab X @tab   @tab X
 @item DVB              @tab X @tab X @tab X @tab X
+@item DVB teletext     @tab   @tab X @tab   @tab E
 @item DVD              @tab X @tab X @tab X @tab X
 @item JACOsub          @tab X @tab X @tab   @tab X
 @item MicroDVD         @tab X @tab X @tab   @tab X
@@ -969,6 +984,8 @@ performance on systems without hardware floating point support).
 
 @code{X} means that the feature is supported.
 
+@code{E} means that support is provided through an external library.
+
 @section Network Protocols
 
 @multitable @columnfractions .4 .1