VDR Software Decoder Plugin
Historically, VDR required an AV711x based DVB PCI card (i.e. full featured card) to decode Audio and Video and to render it's OSD. Since these cards are quite expensive and old-fashioned now, so called budget cards dominate the market. They deliver the MPEG signal to the software and it's the main CPU that decodes it. See also Output devices (VDR wiki) for general information.
There are two answers for the questions: "So what software is there for budget cards in Linux?"
Answer 1: VDR Software Decoder Plugin
However, this plugin is not installed by default, so you have to expect some amount of work to get a software-decoder based VDR setup running.
Answer 2: Xine
Xine comes with full DVB support in its standard installation, therefore one only needs to install the DVB driver and xine and can start watching digital TV. The gxine user interface is very powerful and allows many changes on the run.
- The BerliOS Project homepage of the softdevice project
- Homepage of the xine Plugin for VDR
- The Xine Project Homepage
Some open questions
Sadly, no portable OpenGL-based renderer is known which would allow to build a STB with any cheap modern graphics card. (is this true, allows the xine-plugin OpenGL outputs?)
- I can only speak about the softdevice plugin. It works very well and with any graphics card that supports Xvideo. No 3D-stuff required. For sound it uses Alsa but here I had to use Alsa's dmix plugin else the sound stutters.