AleVT

From LinuxTVWiki
Revision as of 01:22, 17 October 2011 by CityK (Talk | contribs)

Jump to: navigation, search

AleVT is a small suite of software for use with analogue and digital TV Teletext/Videotext.

The main program, AleVT, is used to view or browse teletext. However, having no channel changing capabilities of its own, AleVT is a slave application that must be run in-conjunction with one that can provide tuning. The other utilities included within the parckage are AleVT-date, which can be used to extract date & time information from the teletext, and AleVT-cap, which allows for the capturing of teletext pages to disk.

History & Version Information

Originally written by Edgar Toernig in the late 1990s, AleVT began with support just for analogue TV teletext via Bttv devices (bt848, bt878). Nowadays, the package has much wider V4L device support and also can be / has been (starting as early as 2001 [1]) made to feature support for digital TV teletext.

The last official version of AleVT, v1.6.2, was released in 2007, and is likely available from most Linux distributions. If a package of this release is unavailable for your distribution, you can download the source [2]. Note that this release features support only for analogue TV teletext. However, a number of unofficial patches that extend support to include digital TV teletext are available for this version of AleVT (example). Some distributions have apparently also, at some points, provided patched versions of the app in package form. The varying patched versions were commonly referred to as AleVT-dvb (or alevt-dvb). However, examination of several of these versions found that they were subject to producing a kernel oops while operating with digital teletext. [3]

In 2010, a rewrite and feature extension of AleVT was undertaken (for fuller description of the changes, see the README file), with the resultant work being branded as v1.7.0. In need of a repository home, this newer version was given temporary residency within the LinuxTV dvb-apps, where it still currently resides.[4] [5] [6]. It is, because of its large number of dependencies, excluded by default from the build process for the dvb-apps.

Using AleVT

Since on DVB-T there are multiple TV stations broadcasted on one frequency, alevt can not just show the videotext program of the current channel, but the user has to tell alevt which channel is to be shown. It is recommended to use the script described in the next section to select one of the available teletext providers.

Script for easy use of AleVT

There is a script that shows a graphical dialog with the available TV stations. The user can select the desired TV station by name and the teletext is shown automatically.

The script uses alevt and kdialog, so make sure both is installed!

The script can be downloaded here: [[7]]

To use the script, just run

sh findTxt

on the commandline.

You can put the script on your Desktop and start it directly from there, if you set the executable bit for the script. Also, you can set a shortcut in KDE or Gnome to start the script, e.g. while watching TV. (For help on this, see linux forums :-))

Have Fun!

Manual use of AleVT

AleVT, a slave application, can only be used while running another program (the master application) that performs actual channel tuning. AleVT will show the teletext for the currently running TV station tuned by the master application.

For use with DVB, AleVT must be started like this:

alevt -vbi /dev/dvb/adapter0/demux0

Problematic to that command is the fact that with DVB, on any frequency there may be many channels. In that case, AleVT will just take the first one.

Normally you want to see teletext for the currently running TV station (tuned by the master application). That can be done like follows:

To select a program, you must use the AleVT output:

Service ID 0x000e Type 0x01 Provider Name "ARD" Name "Das Erste"
 PMT PID 0x0578 TXT: PID 0x057c lang ger type 0x01 magazine 1 page   0 
Service ID 0x000c Type 0x01 Provider Name "ARD" Name "rbb Berlin"
 PMT PID 0x04b0 TXT: PID 0x04b4 lang ger type 0x01 magazine 1 page   0

You just have to get the TXT PID for the tv station, e.g. "0x57c" for "Das Erste".

Now run

alevt -vbi /dev/dvb/adapter0/demux0 -pid 0x578 100

Now the Videotext start page should be shown. Note: the "100" at the end of the line leads to the start page, otherwise the start page would have to be selected by hand.

Also See

External Links