threeeye
bc1d038eac
Squashed backup commit (no shallow-clone history issues) of xiaomi-mt6833-dev/kernel_xiaomi_mt6833 (lineage-23.2 branch, upstream commit 9eece662e) plus all fixes applied to get everpal_defconfig building clean against a modern (GCC 15.2.0) toolchain -- see the previous commit message on the lineage-23.2 branch (also in this repo history is not available here since this is a squashed snapshot; full incremental history lives in the local DL380 checkout and the upstream GitHub remote). Upstream: https://github.com/xiaomi-mt6833-dev/kernel_xiaomi_mt6833 (lineage-23.2)
35 lines
1.4 KiB
ReStructuredText
35 lines
1.4 KiB
ReStructuredText
.. -*- coding: utf-8; mode: rst -*-
|
|
|
|
.. _ttx:
|
|
|
|
******************
|
|
Teletext Interface
|
|
******************
|
|
|
|
This interface was aimed at devices receiving and demodulating Teletext
|
|
data [:ref:`ets300706`, :ref:`itu653`], evaluating the Teletext
|
|
packages and storing formatted pages in cache memory. Such devices are
|
|
usually implemented as microcontrollers with serial interface
|
|
(I:sup:`2`\ C) and could be found on old TV cards, dedicated Teletext
|
|
decoding cards and home-brew devices connected to the PC parallel port.
|
|
|
|
The Teletext API was designed by Martin Buck. It was defined in the
|
|
kernel header file ``linux/videotext.h``, the specification is available
|
|
from
|
|
`ftp://ftp.gwdg.de/pub/linux/misc/videotext/ <ftp://ftp.gwdg.de/pub/linux/misc/videotext/>`__.
|
|
(Videotext is the name of the German public television Teletext
|
|
service.)
|
|
|
|
Eventually the Teletext API was integrated into the V4L API with
|
|
character device file names ``/dev/vtx0`` to ``/dev/vtx31``, device
|
|
major number 81, minor numbers 192 to 223.
|
|
|
|
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.
|
|
|
|
Modern devices all use the :ref:`raw <raw-vbi>` or
|
|
:ref:`sliced` VBI API.
|