This interface was aimed at devices receiving and demodulating Teletext data [[ETS 300 706], [ITU BT.653]], evaluating the Teletext packages and storing formatted pages in cache memory. Such devices are usually implemented as microcontrollers with serial interface (I2C) 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
specification is available from
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/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.