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| author | Jiri Kosina <jkosina@suse.cz> | 2011-09-15 15:08:05 +0200 |
|---|---|---|
| committer | Jiri Kosina <jkosina@suse.cz> | 2011-09-15 15:08:18 +0200 |
| commit | e060c38434b2caa78efe7cedaff4191040b65a15 (patch) | |
| tree | 407361230bf6733f63d8e788e4b5e6566ee04818 /Documentation/DocBook/media/v4l/dev-teletext.xml | |
| parent | 10e4ac572eeffe5317019bd7330b6058a400dfc2 (diff) | |
| parent | cc39c6a9bbdebfcf1a7dee64d83bf302bc38d941 (diff) | |
Merge branch 'master' into for-next
Fast-forward merge with Linus to be able to merge patches
based on more recent version of the tree.
Diffstat (limited to 'Documentation/DocBook/media/v4l/dev-teletext.xml')
| -rw-r--r-- | Documentation/DocBook/media/v4l/dev-teletext.xml | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/Documentation/DocBook/media/v4l/dev-teletext.xml b/Documentation/DocBook/media/v4l/dev-teletext.xml new file mode 100644 index 00000000000..414b1cfff9f --- /dev/null +++ b/Documentation/DocBook/media/v4l/dev-teletext.xml @@ -0,0 +1,37 @@ + <title>Teletext Interface</title> + + <para>This interface was aimed at devices receiving and demodulating +Teletext data [<xref linkend="ets300706" />, <xref linkend="itu653" />], evaluating the +Teletext packages and storing formatted pages in cache memory. Such +devices are usually implemented as microcontrollers with serial +interface (I<superscript>2</superscript>C) and could be found on old +TV cards, dedicated Teletext decoding cards and home-brew devices +connected to the PC parallel port.</para> + + <para>The Teletext API was designed by Martin Buck. It was defined in +the kernel header file <filename>linux/videotext.h</filename>, the +specification is available from <ulink url="ftp://ftp.gwdg.de/pub/linux/misc/videotext/"> +ftp://ftp.gwdg.de/pub/linux/misc/videotext/</ulink>. (Videotext is the name of +the German public television Teletext service.)</para> + + <para>Eventually the Teletext API was integrated into the V4L API +with character device file names <filename>/dev/vtx0</filename> to +<filename>/dev/vtx31</filename>, device major number 81, minor numbers +192 to 223.</para> + + <para>However, teletext decoders were quickly replaced by more +generic VBI demodulators and those dedicated teletext decoders no longer exist. +For many years the vtx devices were still around, even though nobody used +them. So the decision was made to finally remove support for the Teletext API in +kernel 2.6.37.</para> + + <para>Modern devices all use the <link linkend="raw-vbi">raw</link> or +<link linkend="sliced">sliced</link> VBI API.</para> + + <!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: + --> |