AleVT
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.
AleVT Usage
AleVT will only properly work when running another program (the master application) that performs the actual channel tuning.
With Analogue TV Teletext
AleVT will show the teletext for the currently running TV station tuned by the master application.
With Digital TV Teletext
Since, in the case with the transmission of digital TV signals, there are often multiple TV stations broadcast on one frequency (i.e. multiplexed within a Transport Stream), AleVT (the slave application) can not just simply show the teletext/videotext program of the current channel tuned by the master application. Rather, AleVT will just take the first channel in the Transport Stream. Consequently, with digital TV services, the user has to tell AleVT from which particular channel contained in the TS, on the tuned frequency, that teletext is to be shown for. It is recommended that the script described in the next section be used to select one of the available teletext providers.
Script for easy use of AleVT
A script is available that provides/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 are installed! This script can be downloaded from: http://martov.de/findTxt
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
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,, as described above, there may be many channels on any particular frequency. Normally you want to see the teletext for the currently running TV station (tuned by the master application). That can be done with AleVT by passing the PID parameter and appropriate value of the program of interest. For example, if your master application was tuned to the station "Das Erste" and the AleVT command above provided the 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
Then to select the teletext for the "Das Erste" channel, you would need to specify the PID "0x57c", like so:
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
- AleVT original homepage ... note: source is not patched for DVB