<title>Teletext Interface</title> <para>This interface aims 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 can be found on older 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 is 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.) Conventional character device file names are <filename>/dev/vtx</filename> and <filename>/dev/vttuner</filename>, with device number 83, 0 and 83, 16 respectively. A similar interface exists for the Philips SAA5249 Teletext decoder [specification?] with character device file names <filename>/dev/tlkN</filename>, device number 102, N.</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. For reference the V4L Teletext API specification is reproduced here in full: "Teletext interfaces talk the existing VTX API." Teletext devices with major number 83 and 102 will be removed in Linux 2.6.</para> <para>There are no plans to replace the Teletext API or to integrate it into V4L2. Please write to the linux-media mailing list: &v4l-ml; when the need arises.</para> <!-- Local Variables: mode: sgml sgml-parent-document: "v4l2.sgml" indent-tabs-mode: nil End: -->