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authorMauro Carvalho Chehab <mchehab@redhat.com>2009-09-13 21:16:04 -0400
committerMauro Carvalho Chehab <mchehab@redhat.com>2009-09-18 22:47:55 -0400
commit8e080c2e6cadada82a6b520e0c23a1cb974822d5 (patch)
tree991450ff1abba98e5313906478c33816a202ccab /Documentation/DocBook/v4l/dev-teletext.xml
parentf4e96deb4513d044653027d4921fd7592195503a (diff)
V4L/DVB (12761): DocBook: add media API specs
The V4L and DVB API's are there for a long time. however, up to now, no efforts were done to merge them to kernel DocBook. This patch adds the current versions of the specs as an unique compendium. Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
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1 <title>Teletext Interface</title>
2
3 <para>This interface aims at devices receiving and demodulating
4Teletext data [<xref linkend="ets300706" />, <xref linkend="itu653" />], evaluating the
5Teletext packages and storing formatted pages in cache memory. Such
6devices are usually implemented as microcontrollers with serial
7interface (I<superscript>2</superscript>C) and can be found on older
8TV cards, dedicated Teletext decoding cards and home-brew devices
9connected to the PC parallel port.</para>
10
11 <para>The Teletext API was designed by Martin Buck. It is defined in
12the kernel header file <filename>linux/videotext.h</filename>, the
13specification is available from <ulink url="http://home.pages.de/~videotext/">
14http://home.pages.de/~videotext/</ulink>. (Videotext is the name of
15the German public television Teletext service.) Conventional character
16device file names are <filename>/dev/vtx</filename> and
17<filename>/dev/vttuner</filename>, with device number 83, 0 and 83, 16
18respectively. A similar interface exists for the Philips SAA5249
19Teletext decoder [specification?] with character device file names
20<filename>/dev/tlkN</filename>, device number 102, N.</para>
21
22 <para>Eventually the Teletext API was integrated into the V4L API
23with character device file names <filename>/dev/vtx0</filename> to
24<filename>/dev/vtx31</filename>, device major number 81, minor numbers
25192 to 223. For reference the V4L Teletext API specification is
26reproduced here in full: "Teletext interfaces talk the existing VTX
27API." Teletext devices with major number 83 and 102 will be removed in
28Linux 2.6.</para>
29
30 <para>There are no plans to replace the Teletext API or to integrate
31it into V4L2. Please write to the linux-media mailing list: &v4l-ml;
32when the need arises.</para>
33
34 <!--
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