Digital Video Recorders, PVR

A digital video recorder (DVR) is a device that records video to a digital storage medium in digital form. The term DVR may be used to describe a piece of equipment such as a Personal Video Recorder (PVR) or a CCTV DVR. more...

It may also be used to reference a function in a piece of equipment such as a digital video camera that has a DVR function built into it.

Television and video are terms that are sometimes used interchangeably but in their narrow definitions are different. Video is the visual portion of television where as television is video and audio modulated onto, (combined with), a carrier frequency, (television channel), so that it may be transported either wirelessly or over cables with many other frequencies, (channels).

History

The first DVR was tested on July 8th, 1965, when CBS explored the possibilities of instant freeze-frame and rewind for sporting event broadcasts. Ampex released the first commercial hard disk video recorder in 1967. The HS-100 recorded analog video onto a digital hard disk and could store a maximum of only 30 seconds.

Personal Video Recorder (PVR)

The personal video recorder (PVR) or digital personal video recorder, is a consumer electronics device that records television shows to a hard disk in digital format.

The two earliest consumer DVRs, ReplayTV and TiVo, were launched at the 1999 Consumer Electronics Show in Las Vegas. Ironically, although ReplayTV won the "Best of Show" award in the video category, it was Tivo that went on to much greater commercial success. The devices have steadily developed complementary abilities, such as recording onto DVDs, commercial skip, sharing of recordings over the Internet, and programming and remote control facilities using PDAs, networked PCs, or web browsers.

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 DVR recorders use the MPEG format for encoding analog video signals.

The two consumer DVR brands in the United States are the TiVo and DNNA's ReplayTV. In the UK TiVO has a small presence; Thomson, Fusion, Pace and Humax also supply digital terrestrial (DTT) DVRs. However it is BSkyB's Sky+ that dominates the marketplace. Indeed, their box, which links the hard recorder and their own EPG and is already in over a million UK homes, has become so successful that the verb 'to Sky Plus' (meaning to have recorded it on to PVR) has entered contemporary English phraseology in the same way as 'to hoover' did decades earlier.

Many satellite and cable companies are incorporating DVR functions into their set-top box, such as with DirecTiVo, Motorola 6xxx from Comcast, Moxi Media Center by Digeo (available through Charter, Adelphia, Sunflower, Bend Broadband, and soon Comcast and other cable companies), or Sky Plus. In this case there is no encoding necessary in the DVR, as the satellite signal is already a digitally encoded MPEG stream. The DVR simply stores the digital stream directly to disk. Having the broadcaster involved with (subsidizing) the design of the DVR, and directly recording encrypted digital streams can lead to fancy features - like the ability to use interactive TV on recorded shows, pre-loading of programs; but can also lead to too much control by the broadcaster - like denying the ability to skip adverts and automatically expiring recordings after a time determined by the broadcaster.

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