There are two ways:
Hardware MPEG decoder
The principle of the VDR software is avoiding to deal with MPEG data on software side as much as possible. Therefore, for viewing of the MPEG2 stream provided by the DVB card, an MPEG2 hardware decoder is needed. Up to now there are three different hardware possibilities:
- full-featured DVB card (a DVB card which has not only the tuner onboard, but also the hardware decoder with TV-Out)
- Dxr3 or Hollywood-Plus MPEG decoder card (MPEG decoder card, originally used for DVD viewing on slow computers)
- Hauppauge WinTV PVR350 (analogue TV card with onboard hardware MPEG2 decoder)
As one sees, many of these cards are not purely output but rather input and output cards.
Software MPEG decoder
Now that many computers are fast enough (CPU 500 MHz and more), there is also the possibility of software decoding. In fact, many (most?) input cards sold nowadays are so-called budget cards, i.e. don't have hardware decoders any more. The decoding is done by the CPU and the output is usually given to the normal graphic card. There are a number of VDR software decoder plugins available, they are:
- Softdevice-plugin Provides excellent output on VGA hardware using X11 or DirectFB. Can also do hardware MPEG2 acceleration on motherboards provided with CLE266 chipset. Can also do field perfect interlaced output using Matrox G450/550 cards under DirectFB.
- Xine-plugin (requires xine, gxine or some other xine-lib front-end). Xine can also use the hardware MPEG2 acceleration feature of the EPIA M motherboards with CLE266 chipset. Software playback on EPIA.