<title>Opening and Closing Devices</title>
<para>For compatibility reasons the character device file names
-recommended for V4L2 video capture, overlay, radio, teletext and raw
+recommended for V4L2 video capture, overlay, radio and raw
vbi capture devices did not change from those used by V4L. They are
listed in <xref linkend="devices" /> and below in <xref
linkend="v4l-dev" />.</para>
+ <para>The teletext devices (minor range 192-223) have been removed in
+V4L2 and no longer exist. There is no hardware available anymore for handling
+pure teletext. Instead raw or sliced VBI is used.</para>
+
<para>The V4L <filename>videodev</filename> module automatically
assigns minor numbers to drivers in load order, depending on the
registered device type. We recommend that V4L2 drivers by default
<filename>/dev/radio63</filename></para></entry>
<entry>64-127</entry>
</row>
- <row>
- <entry>Teletext decoder</entry>
- <entry><para><filename>/dev/vtx</filename>,
-<filename>/dev/vtx0</filename> to
-<filename>/dev/vtx31</filename></para></entry>
- <entry>192-223</entry>
- </row>
<row>
<entry>Raw VBI capture</entry>
<entry><para><filename>/dev/vbi</filename>,
</listitem>
</orderedlist>
</section>
+ <section>
+ <title>V4L2 in Linux 2.6.37</title>
+ <orderedlist>
+ <listitem>
+ <para>Remove the vtx (videotext/teletext) API. This API was no longer
+used and no hardware exists to verify the API. Nor were any userspace applications found
+that used it. It was originally scheduled for removal in 2.6.35.
+ </para>
+ </listitem>
+ </orderedlist>
+ </section>
<section id="other">
<title>Relation of V4L2 to other Linux multimedia APIs</title>
<title>Teletext Interface</title>
- <para>This interface aims at devices receiving and demodulating
+ <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 can be found on older
+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 is defined in
+ <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.) 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>
+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. 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>
+192 to 223.</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>
+ <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:
<year>2007</year>
<year>2008</year>
<year>2009</year>
+ <year>2010</year>
<holder>Bill Dirks, Michael H. Schimek, Hans Verkuil, Martin
Rubli, Andy Walls, Muralidharan Karicheri, Mauro Carvalho Chehab</holder>
</copyright>
<!-- Put document revisions here, newest first. -->
<!-- API revisions (changes and additions of defines, enums,
structs, ioctls) must be noted in more detail in the history chapter
-(compat.sgml), along with the possible impact on existing drivers and
+(compat.xml), along with the possible impact on existing drivers and
applications. -->
+ <revision>
+ <revnumber>2.6.37</revnumber>
+ <date>2010-08-06</date>
+ <authorinitials>hv</authorinitials>
+ <revremark>Removed obsolete vtx (videotext) API.</revremark>
+ </revision>
+
<revision>
<revnumber>2.6.33</revnumber>
<date>2009-12-03</date>
Why: Superseded by xt_CT
Who: Netfilter developer team <netfilter-devel@vger.kernel.org>
----------------------------
-
-What: video4linux /dev/vtx teletext API support
-When: 2.6.35
-Files: drivers/media/video/saa5246a.c drivers/media/video/saa5249.c
- include/linux/videotext.h
-Why: The vtx device nodes have been superseded by vbi device nodes
- for many years. No applications exist that use the vtx support.
- Of the two i2c drivers that actually support this API the saa5249
- has been impossible to use for a year now and no known hardware
- that supports this device exists. The saa5246a is theoretically
- supported by the old mxb boards, but it never actually worked.
-
- In summary: there is no hardware that can use this API and there
- are no applications actually implementing this API.
-
- The vtx support still reserves minors 192-223 and we would really
- like to reuse those for upcoming new functionality. In the unlikely
- event that new hardware appears that wants to use the functionality
- provided by the vtx API, then that functionality should be build
- around the sliced VBI API instead.
-Who: Hans Verkuil <hverkuil@xs4all.nl>
-
----------------------------
What: IRQF_DISABLED
<mailto:oe@port.de>
'z' 10-4F drivers/s390/crypto/zcrypt_api.h conflict!
0x80 00-1F linux/fb.h
-0x81 00-1F linux/videotext.h
0x88 00-3F media/ovcamchip.h
0x89 00-06 arch/x86/include/asm/sockios.h
0x89 0B-DF linux/sockios.h
echo "*** new device names ***"
makedev video 0
makedev radio 64
-makedev vtx 192
makedev vbi 224
#echo "*** old device names (for compatibility only) ***"
2) A way of initializing and commanding sub-devices (if any).
-3) Creating V4L2 device nodes (/dev/videoX, /dev/vbiX, /dev/radioX and
- /dev/vtxX) and keeping track of device-node specific data.
+3) Creating V4L2 device nodes (/dev/videoX, /dev/vbiX and /dev/radioX)
+ and keeping track of device-node specific data.
4) Filehandle-specific structs containing per-filehandle data;
VFL_TYPE_GRABBER: videoX for video input/output devices
VFL_TYPE_VBI: vbiX for vertical blank data (i.e. closed captions, teletext)
VFL_TYPE_RADIO: radioX for radio tuners
-VFL_TYPE_VTX: vtxX for teletext devices (deprecated, don't use)
The last argument gives you a certain amount of control over the device
device node number used (i.e. the X in videoX). Normally you will pass -1
projects / mv-sheeva.git / commitdiff