what is a PVR or so called DVR?

The personal video recorder (PVR), also called digital video recorder (DVR) or digital personal video recorder, is a consumer electronics device that records television shows to a hard disk in digital format. Since first introduced by TiVo at the Consumer Electronics Show in 1999, PVRs have steadily developed complementary abilities, such as recording onto DVDs. This makes the "time shifting" feature (traditionally done by a VCR) much more convenient, and also allows for "trick modes" such as pausing live TV, instant replay of interesting scenes, and skipping advertising. Most PVR recorders use the MPEG format for encoding analog video signals. The most popular PVRs on the market are the TiVo and DNNA's ReplayTV, although most home electronics manufacturers now offer models. Many satellite and cable companies are incorporating PVR functions into their set-top box, such as with DirecTiVo, Motorola 6xxx from Comcast, or Sky+. In this case there is no encoding necessary in the PVR, as ...