Hardware or software decoder?

It use to be common for DVB cards to contain a hardware MPEG2 decoder, so that the incoming MPEG stream would be decoded on the card itself.

• these cards featured a decoder that is capable of MP@ML only ... i.e. up to SDTV resolutions only).
• therefore alleviating the host system's CPU from such a task i.e don't use the CPU resources (but more PCI bus resources are used though...large uncompressed SDTV stream).

This hardware decoding class of cards are often referred to as Premium or Full-featured Cards. This is rather a misnomer given that:

• the MPEG decoders are incapable of MP@HL
• ATSC hardware decoding cards -- uncommon to see such labels applied to them, and yet, they were capable of MP@HL (i.e more full-featured then their DVB-x counterparts)

Nowadays, most cards can be classified as software decoding devices. Instead, the still encoded, unchanged stream goes to the CPU and is decoded based upon the algorithms of a software decoder. These cards are also sometimes referred to, in antiquated terms, as budget cards, i.e. a reference to the fact that they lack a MPEG decoder chip, as would be found on a so called "premium" or "full-featured card".

Also see:

• VDR Software Decoder Plugin
• Output devices (VDR wiki)