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Users: Tune Your Television
DVB is a new standard for transmission of digital video and audio. DVB-T is its subset describing terrestrial protocol transmission which can be captured with regular TV antenna. Many European countries broadcast DVB-T signal in addition to the old analog TV signal which is slowly being abandoned. By 2012 all EU countries are supposed to replace the old analog broadcasting with DVB-T.
DVB format is very "user friendly" - it is an mpeg stream. As a result the simplest thing to do with it is to record it - one does not need to do any encoding, just store the data on a disk. Streaming is also very easy as most of the movie players directly understands the format. The only problem that has to be solved is management of the actual DVB card - e.g. tuning it, allowing multiple programs to read data from it (as it is usually possible to process about five or even more channels at one), scheduling recordings. This is the right job for DVB Central - it contains command line interface so it can run on a server, HTTP server for easy configuration via browser and for broadcasting video, it can record files to disk, it can multicast them to network using RTP, and much, much more.
After a half a year of development this project is ready to announce the general availability of a working version ready for public consumption. The version is running in a production environment (e.g. on my server at home, used by my wife) and has been heavily tested by always demanding users (my wife cannot understand that bugs are natural) and as such it seems to be ready for general usage. That is why go on and download the new binary release, unzip it and execute bin/dvbcentral script.
It is necessary to have a config file in /etc/dvb/channels.conf, $HOME/.mplayer/channels.conf or $HOME/.xine/channels.conf. The format of the file should match the one used by mplayer, xine & co.
The possible arguments include --station name to tune the right station, --stdout to send the TS mpeg stream to standard output, --file name to save the stream to a given file and --rtp 224.0.1.2:5004 to broadcast the TS around local network. Very useful is also embedded execution of other commands, so one can use for example --exec -- mplayer - to send the data to mplayer embedded as an subprocess. The important feature of the application is that it can be started without any arguments, left running and then started once again (or many times) with proper arguments. The first instance is then going to act as a server and the other ones are going to connect to it and give it proper instructions of what to do.
Developers: Use DVB libraries to access DVB in Java
Certain libraries produced by this project can be easily incorporated into other standalone java applications. Probably the most interesting one for Java programmers that are interested in DVB is the Frontend wrapper. It is a set of classes wrapping native calls to Linux DVB API.
The online javadoc of the Frontend library is available here. To get the library itself, download some binary release of DVB Central and pickup net-sf-dvbcentral.jar from it.
The library runs only on Linux as it uses a native wrapper to do necessary ioctl calls. These calls are carefully wrapped with the pure java classes like:
- Frontend - that represents one DVB card installed on your computer
- Tune - describing frequencies, polarizations, etc. necessary to tune the card in given countries
Developers: Extend DVB Central Application
The DVB central is built in a modular way with a set of extensible APIs and it is easy to extend its functionality by writing additional components. The goal is to encourage other developers to extend the dvbcentral's functionality with out extensions.
The general motivation and examples are given in the NetBeans Runtime Container manifesto page. However all one needs to do to easily start developing against dvbcentral, is to download the binary release and install it as a NetBeans platform into NetBeans IDE 5.5 or (better) 6.0.
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